## Why
logarchiver encrypts archived logs to an OpenPGP key held in Vault's gpg engine so the private key never leaves Vault (retrieval delegates decryption to `gpg/decrypt/logarchive`, operator-only). This provisions the key and lets the service read only its public key.
## Changes
- Create gpg key `logarchive` (rsa-4096, non-exportable) in the `gpg` mount.
- Add k8s auth role `logging_logarchiver` bound to SA `logarchiver` in the `logging` namespace.
- Add policy granting `read` on `gpg/keys/logarchive` to that role (public key only; no decrypt/export).
Cross-repo: this must apply before the argocd-apps logarchiver Deployment (unkin/argocd-apps) can fetch the key.
https://claude.ai/code/session_015ur3i7D2azsMAWTSVABApv
---------
Co-authored-by: benvin <neotheo@gmail.com>
Reviewed-on: #106
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
Complete the deploy of the [vault-plugin-secrets-gpg](https://git.unkin.net/unkin/vault-plugin-secrets-gpg) engine. Puppet ([puppet-prod #480](unkin/puppet-prod#480)) installs the `openbao-plugin-secrets-gpg` RPM onto the OpenBao nodes; this registers that binary in the plugin catalog and enables the secrets engine so `gpg/` is actually usable.
- Add a `gpg_secret_backend` module using the standard `hashicorp/vault` provider (already required at 5.6.0): `vault_plugin` (catalog register with a pinned sha256) + `vault_mount` (enable at the mount path).
- Wire it through `vault_cluster` (new `gpg_secret_backend` variable + module block) and the config discovery (`config.hcl` group + syd1 terragrunt input), mirroring `litellm_secret_backend`.
- Add `config/gpg_secret_backend/gpg.yaml` mounting at `gpg/` and pinning the released v0.1.0 binary sha256 (`0e92d740…a7b20`, extracted from the published RPM). Puppet installs the RPM floating, so this sha must be bumped in lockstep on any plugin upgrade or OpenBao rejects the binary.
Validated locally with `tofu validate` + `tofu fmt`. Granting non-root access to `gpg/*` (auth roles + policies) is a follow-up scoped to whoever consumes the engine (e.g. passv from CI).
Reviewed-on: #87
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
unkinben