## Summary
- Add `containers/nettest/default.nix` using `dockerTools.buildLayeredImage` with curl, jq, dnsutils, cacert, and bash — equivalent to the existing Dockerfile
- Update `container-tag-and-release` to require `--nix` or `--dockerfile` flag when both build types exist for a container
- Update `container-list` to show `[dockerfile+nix]` label when both exist
## Deployment and Testing
- [ ] SSH to ringtail, run `nix build -f containers/nettest/default.nix -o result` to verify the nix expression builds
- [ ] Tag `nettest-nix-v1.0.0`, confirm `build-container-nix` workflow runs on `nix-container-builder` runner and pushes to registry
- [ ] Smoke test on ringtail k3s: `kubectl run nettest --image=registry.ops.eblu.me/blumeops/nettest:v1.0.0 --restart=Never && kubectl logs nettest`
- [ ] Verify `mise run container-list` shows `[dockerfile+nix]` for nettest
- [ ] Verify `mise run container-tag-and-release nettest v1.1.0` prompts for build type
Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/214
## Summary
Extends ringtail from a desktop/gaming NixOS box into an infrastructure node with a k3s cluster, secrets management, and a Forgejo Actions
runner for building containers with Nix.
### K3s cluster
- Single-node k3s with Traefik/ServiceLB/metrics-server disabled (minimal footprint)
- TLS SAN set to `ringtail.tail8d86e.ts.net` so ArgoCD on indri can manage it via Tailscale
- Containerd registry mirrors pull through Zot on indri (`k3s-registries.yaml`)
- Tailscale interface added to `trustedInterfaces` for cross-node ArgoCD access
- `kubectl` added to system packages
### 1Password Connect + External Secrets Operator
- Four new ArgoCD apps targeting `k3s-ringtail`: `1password-connect-ringtail`, `external-secrets-crds-ringtail`, `external-secrets-ringtail`,
`external-secrets-config-ringtail`
- Reuses the same Helm charts/values as indri, just pointed at ringtail's k3s API server
- Bootstrap secrets (`op-credentials`, `onepassword-token`) provisioned by Ansible pre_tasks via `op read`, then applied to the `1password`
namespace in post_tasks
### Systemd Forgejo Actions runner
- Native `services.gitea-actions-runner` with `forgejo-runner` package — no DinD, no k8s pod, runs directly on the NixOS host
- Label `nix-container-builder:host` — jobs execute on the host with `nix`, `skopeo`, `nodejs`, etc. in PATH
- Registration token fetched from 1Password (`Forgejo Secrets/runner_reg`) by Ansible and written to `/etc/forgejo-runner/token.env`
- Runner's dynamic user (`gitea-runner`) added to `nix.settings.trusted-users` for nix daemon access
### Nix container build workflow
- New `.forgejo/workflows/build-container-nix.yaml` triggers on `*-nix-v[0-9]*` tags (e.g. `nettest-nix-v1.0.0`)
- Builds with `nix build -f containers/<name>/default.nix`, pushes to Zot via `skopeo copy`
- Existing Dockerfile workflow guarded with `if: !contains(github.ref_name, '-nix-v')` to avoid double-triggering
### Mise task updates
- `container-tag-and-release` auto-detects `default.nix` vs `Dockerfile` and uses the appropriate tag format (`-nix-v` vs `-v`)
- `container-list` shows build type indicator (`[nix]` / `[dockerfile]`)
## Post-merge
1. `mise run provision-ringtail` — deploys k3s token, runner token, NixOS rebuild
2. Register k3s cluster in ArgoCD (first time only):
```fish
ssh ringtail 'sudo cat /etc/rancher/k3s/k3s.yaml' | \
sed 's|127.0.0.1|ringtail.tail8d86e.ts.net|' > /tmp/k3s-ringtail.yaml
set -x KUBECONFIG /tmp/k3s-ringtail.yaml
argocd cluster add default --name k3s-ringtail
3. Sync ArgoCD apps in order: 1password-connect-ringtail -> external-secrets-crds-ringtail -> external-secrets-ringtail ->
external-secrets-config-ringtail
4. Verify runner: ssh ringtail 'systemctl status gitea-runner-nix-container-builder'
5. Check Forgejo admin panel for ringtail-nix-builder runner online
6. Test: create containers/<name>/default.nix, tag with <name>-nix-v0.1.0
Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/209
