111 lines
3.7 KiB
Markdown
111 lines
3.7 KiB
Markdown
# Secrets
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Secrets are managed using [git-crypt][git-crypt] and [agenix][agenix]
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so you can keep your flake in a public repository like GitHub without
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exposing your password or other sensitive data.
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By default, everything in the secrets folder is automatically encrypted. Just
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be sure to run `git-crypt init` before putting anything in here.
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## Agenix
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Currently, there is [no mechanism][secrets-issue] in nix itself to deploy secrets
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within the nix store because it is world-readable.
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Most NixOS modules have the ability to set options to files in the system, outside
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the nix store, that contain sensitive information. You can use [agenix][agenix]
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to easily setup those secret files declaratively.
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[agenix][agenix] encrypts secrets and stores them as .age files in your repository.
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Age files are encrypted with multiple ssh public keys, so any host or user with a
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matching ssh private key can read the data. The [age module][age module] will add those
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encrypted files to the nix store and decrypt them on activation to `/run/secrets`.
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### Setup
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All hosts must have openssh enabled, this is done by default in the core profile.
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You need to populate your `secrets/secrets.nix` with the proper ssh public keys.
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Be extra careful to make sure you only add public keys, you should never share a
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private key!!
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secrets/secrets.nix:
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```nix
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let
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system = "<system ssh key>";
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user = "<user ssh key>";
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allKeys = [ system user ];
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in
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```
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On most systems, you can get your systems ssh public key from `/etc/ssh/ssh_host_ed25519_key.pub`. If
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this file doesn't exist you likely need to enable openssh and rebuild your system.
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Your users ssh public key is probably stored in `~/.ssh/id_ed25519.pub` or
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`~/.ssh/id_rsa.pub`. If you haven't generated a ssh key yet, be sure do so:
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```sh
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ssh-keygen -t ed25519
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```
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> ##### _Note:_
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> The underlying tool used by agenix, rage, doesn't work well with password protected
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> ssh keys. So if you have lots of secrets you might have to type in your password many
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> times.
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### Secrets
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You will need the `agenix` command to create secrets. DevOS conveniently provides that
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in the devShell, so just run `nix develop` whenever you want to edit secrets. Make sure
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to always run `agenix` while in the `secrets/` folder, so it can pick up your `secrets.nix`.
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To create secrets, simply add lines to your `secrets/secrets.nix`:
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```
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let
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...
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allKeys = [ system user ];
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in
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{
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"secret.age".publicKeys = allKeys;
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}
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```
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That would tell agenix to create a `secret.age` file that is encrypted with the `system`
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and `user` ssh public key.
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Then go into the `secrets` folder and run:
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```sh
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agenix -e secret.age
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```
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This will create the `secret.age`, if it doesn't already exist, and allow you to edit it.
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If you ever change the `publicKeys` entry of any secret make sure to rekey the secrets:
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```sh
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agenix --rekey
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```
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### Usage
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Once you have your secret file encrypted and ready to use, you can utilize the [age module][age module]
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to ensure that your secrets end up in `/run/secrets`.
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In any profile that uses a NixOS module that requires a secret you can enable a particular secret like so:
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```nix
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{ self, ... }:
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{
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age.secrets.mysecret.file = "${self}/secrets/mysecret.age";
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}
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```
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Then you can just pass the path `/run/secrets/mysecret` to the module.
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You can make use of the many options provided by the age module to customize where and how
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secrets get decrypted. You can learn about them by looking at the
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[age module][age module].
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> ##### _Note:_
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> You can take a look at the [agenix repository][agenix] for more information
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> about the tool.
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[git-crypt]: https://github.com/AGWA/git-crypt
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[agenix]: https://github.com/ryantm/agenix
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[age module]: https://github.com/ryantm/agenix/blob/master/modules/age.nix
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[secrets-issue]: https://github.com/NixOS/nix/issues/8
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