Fediversity/secrets/README.md

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# Secrets
Secrets are handled using [Agenix](https://github.com/ryantm/agenix).
## Cheat sheet
### Adding a secret
As an example, let us add a secret in a file “cheeses” whose content should be
“best ones come unpasteurised”.
1. Edit [`secrets.nix`](./secrets.nix), adding a field to the final record with
the file name mapped to the systems that should be able to decrypt the
secret, for instance:
```nix
cheeses = [ vm02116 forgejo-ci ];
```
2. Run Agenix to add the content of the file. Agenix is provided by the
development Shell but can also be run directly with `nix run
github:ryantm/agenix --`. Run `agenix -e cheeses.age` (with the `.age`
extension); this will open your `$EDITOR` ; enter “best ones come
unpasteurised”, save and close.
3. If you are doing something flake-related such as NixOps4, remember to commit
or at least stage the secret.
4. In the machine's configuration, load our `ageSecrets` NixOS module, declare the machine's host key and start using your secrets, eg.:
```nix
{ self, config, ... }:
{
imports = [ self.nixosModules.ageSecrets ];
fediversity.hostPublicKey = self.keys.systems.vmFromage;
services.imaginaryCheeseFactory.frenchSecretFile = config.age.secrets.cheeses.path;
}
```
If the secrets requires specific owner/group/mode, those can be set with:
```nix
age.secrets.cheeses.owner = "jeanpierre";
age.secrets.cheeses.group = "france";
age.secrets.cheeses.mode = "440";
```
5. Never read the content of the file in Nix, that is never do anything like:
```nix
services.imaginaryCheeseFactory.frenchSecret = readFile config.age.secrets.cheeses.path;
```
This will put the secret as a world-readable file in the Nix store. The
service that you are using must be able to read from a file at runtime, and
if the NixOS default module options do not provide that, you must find a way
around it.