dendritic/.github/instructions/soteria-host.instructions.md

---
description: "Use when modifying the Soteria host definition or host-local secrets under modules/hosts/soteria. Covers host wiring and SSH cert mechanics specific to Soteria."
name: "Soteria Host Instructions"
applyTo: "modules/hosts/soteria/**/*.nix, modules/hosts/soteria/secrets.yaml"
---

# Soteria Host Instructions

Use this instruction when changing Soteria host wiring in `modules/hosts/soteria`.

## Host Intent And Shape

- Treat Soteria as a NixOS service node for Forgejo, RESTic server, mTLS, and a paired Home Manager profile for `john`.
- Keep host identity aligned: `hostname = "soteria"`, `networking.hostName = hostname`, and `flake.nixosConfigurations."${hostname}"`.
- Keep host-local secrets in `modules/hosts/soteria/secrets.yaml` and wire with `sops.defaultSopsFile = ./secrets.yaml`.
- Keep host-specific Home Manager wiring in `flake.modules.homeManager.soteria`, and keep `mysops.hostSecretFile` pointing at the Soteria secrets file.

## Required Module Composition

When editing `modules/hosts/soteria/default.nix`, preserve this composition unless the task explicitly changes architecture:

- Import `nixos.ssh-certs` to enable host SSH cert integration.
- Import `nixos.janus-ca` so Step client trust material and defaults remain available.
- Import `nixos.restic-server` so the RESTic REST server implementation lives in the shared module rather than inline host wiring.
- Keep `ssh-certs.hostname = hostname;` so cert principals match host naming.

## SSH Cert Mechanics On Soteria

Soteria SSH certificate behavior is the result of multiple modules. Keep this flow intact:

1. `soteria/default.nix` imports `nixos.ssh-certs` and sets `ssh-certs.hostname = "soteria"` (via `hostname`).
2. `modules/services/step-ca/ssh-host.nix`:
   - Enables `ssh.certificates.enable = true`.
   - Requires `sops.secrets."janus/admin_jwk"` (provisioner credential) from Soteria's `secrets.yaml`.
   - Defines cert paths at `/etc/ssh/ssh_host_ed25519_key` and `/etc/ssh/ssh_host_ed25519_key-cert.pub`.
   - Exposes `ssh-host-cert-renew` and `ssh-host-cert-check` helper binaries.
   - Schedules `ssh-certs-renew.timer` every 4h with jitter.
3. `modules/services/ssh.nix` consumes `ssh.certificates.enable` and configures OpenSSH to:
   - Set `TrustedUserCAKeys = /etc/ssh/ssh_user_ca_key.pub`.
   - Set `HostCertificate = /etc/ssh/ssh_host_ed25519_key-cert.pub`.
   - Install the trusted user CA file into `/etc/ssh/ssh_user_ca_key.pub`.
4. `nixos.janus-ca` provides Step CA trust bootstrapping (`/etc/step-ca/defaults.json` and linked root CA material), allowing Step CLI operations to trust and reach the CA endpoint.

Current implementation note:

- `ssh-certs-renew.service` currently checks renewal state via `step ssh needs-renewal` and logs status. It does not directly invoke `ssh-host-cert-renew` in the service script. Preserve this behavior unless the task explicitly asks to change renewal execution semantics.

## SOPS/Secrets Mechanics On Soteria

Soteria secret handling spans host-local secrets, NixOS secret materialization, and Home Manager secret tooling. Keep this flow intact:

1. `modules/hosts/soteria/default.nix` imports `nixos.mysops` and sets `sops.defaultSopsFile = ./secrets.yaml`.
2. The SOPS file `modules/hosts/soteria/secrets.yaml` is the canonical encrypted source for this host's system secrets.
3. Shared modules imported by Soteria declare required secret entries under `sops.secrets` and consume them through `config.sops.secrets.<name>.path`:
   - `modules/services/step-ca/ssh-host.nix` declares and consumes `janus/admin_jwk` as the Step provisioner password file.
   - `modules/features/forgejo.nix` declares and consumes `forgejo/secret_key`, `forgejo/internal_token`, `forgejo/jwt_secret`, and `forgejo/lfs_jwt_secret`.
4. Secret ownership is module-defined and must stay aligned with service users:
   - Forgejo secrets are owned by `config.services.forgejo.user`.
   - Step SSH provisioner secret is locked to root ownership and `0400` mode.
5. `flake.modules.homeManager.soteria` imports `homeManager.mysops` and sets `mysops.hostSecretFile` to the same Soteria host secret file path. This drives helper tooling such as `edit-secrets` while Home Manager keeps its own default SOPS context from `modules/programs/sops.nix`.

Current implementation note:

- `restic_password` exists in `modules/hosts/soteria/secrets.yaml`, but it is not currently consumed by the Soteria NixOS module graph.
- Changing, deleting, or renaming seemingly unused keys in `secrets.yaml` should be treated as a compatibility change and confirmed by the task.

## Restic REST Server On Soteria

Soteria's RESTic REST server is implemented by the shared `nixos.restic-server` module and configured by host-local `resticServer` values. Trace it this way:

1. `modules/hosts/soteria/default.nix` imports `nixos.restic-server` and configures the host-local `resticServer` option set with:
   - `enable = true`
   - `dataDir = "/mnt/restic"`
   - `privateRepos = true`
   - `listenAddress = "0.0.0.0:8000"`
   - `tls.certFile = config.mtls.certFile`
   - `tls.keyFile = config.mtls.keyFile`
2. `modules/features/restic.nix` maps those `resticServer` options into `services.restic.server` and appends TLS flags when both TLS paths are set.
3. The shared module keeps the server base behavior in one place:
   - `services.restic.server.enable = true`
   - `services.restic.server.dataDir = cfg.dataDir`
   - `services.restic.server.listenAddress = cfg.listenAddress`
   - `services.restic.server.privateRepos = cfg.privateRepos`
   - `services.restic.server.extraFlags = cfg.extraFlags ++ tlsFlags`
4. `modules/features/restic.nix` also opens the matching TCP port through `networking.firewall.allowedTCPPorts`, deriving it from `resticServer.listenAddress`.
5. The mTLS renewal hook includes `restic-rest-server.service` in `mtls.renew.reloadUnits`, so certificate rotation reloads the REST server alongside Forgejo.
6. `loginText.extraServiceStatus` exposes the running unit as `restic-rest-server.service`, which is the service name to keep in mind for status and reload behavior.

### Storage Location

- Soteria explicitly sets `resticServer.dataDir = "/mnt/restic"`.
- The shared module maps that value into `services.restic.server.dataDir`, so `/mnt/restic` is now the intended repository storage location for this host.
- The shared module also derives the firewall port from `resticServer.listenAddress`, so Soteria no longer needs a separate `networking.firewall.allowedTCPPorts = [ 8000 ]` line.
- If storage needs to move later, change the `resticServer.dataDir` input or the shared module contract, not ad hoc service cleanup logic.
- `privateRepos = true` constrains repo exposure behavior, but it does not define storage location by itself.

Current implementation note:

- The REST server is TLS-protected but currently passed `--no-auth`, so client access control relies on transport/security model rather than rest-server password auth.
- The shared module default listen address is not Soteria's deployed value; Soteria deliberately overrides it to `0.0.0.0:8000` in the host.

## Forgejo Implementation On Soteria

Soteria's Forgejo setup is split between host-local option values and the shared `nixos.forgejo` module. Trace it this way:

1. `modules/hosts/soteria/default.nix` imports `nixos.forgejo` and enables it with:
   - `forgejo.enable = true`
   - `forgejo.root_url = "https://forgejo.john-stream.com"`
   - `forgejo.https = true`
   - `forgejo.port = 443`
2. `modules/features/forgejo.nix` defines `forgejo.port` as the controlling option for the web listener. Its default is `3000`, but Soteria overrides it to `443`.
3. The shared module wires that option into multiple places:
   - `services.forgejo.settings.server.HTTP_PORT = cfg.port`
   - `networking.firewall.allowedTCPPorts = [ cfg.port ]` when `openFirewall = true`
   - If `cfg.port < 1024`, the Forgejo systemd unit gets `CAP_NET_BIND_SERVICE` so it can bind a privileged port.
4. HTTPS on Soteria is terminated directly by Forgejo using mTLS-managed files:
   - `services.forgejo.settings.server.PROTOCOL = "https"`
   - `KEY_FILE = config.mtls.keyFile`
   - `CERT_FILE = config.mtls.certFile`

### Storage Locations

- This repo does not override Forgejo's primary state directory in the Soteria host or in `modules/features/forgejo.nix`.
- That means Forgejo storage follows the underlying NixOS `services.forgejo` defaults, exposed in this config as `config.services.forgejo.stateDir`.
- PostgreSQL storage is also left at the underlying module default and is referenced as `config.services.postgresql.dataDir`.
- The cleanup helpers in `modules/features/forgejo.nix` confirm these are the intended storage anchors because they remove exactly `config.services.forgejo.stateDir` and `config.services.postgresql.dataDir`.
- Forgejo backup dumps are generated by `forgejo-dump.service` using `--work-path ${config.services.forgejo.dump.backupDir}`, so dump staging/output follows the Forgejo module's backup directory setting rather than a Soteria-specific path override.

Current implementation note:

- If you need to change Forgejo storage location on Soteria, do it by setting the underlying Forgejo or PostgreSQL service directory options explicitly, not by changing cleanup scripts alone.
- If you need to change the external Forgejo endpoint, update `forgejo.root_url`, `forgejo.port`, and the Soteria mTLS SAN list together.

## Change Safety Rules

- Do not rename the secret key `janus/admin_jwk` without updating all consumers.
- Do not change SSH host key/cert filenames unless OpenSSH `HostKey`/`HostCertificate` paths are updated together.
- If changing hostnames or domains, update cert principals in `ssh-certs` and corresponding SSH client targets together.
- If adding or removing `nixos.ssh-certs`, explain impact on SSH cert issuance, renewal, and trust in the change summary.