Add plan: distilled Gitea Actions image-build workflow

Co-Authored-By: Claude <noreply@anthropic.com>

docs/plans/2026-08-11-1935-gitea-build-workflow.md

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+# Plan: Distilled Gitea Actions image-build workflow
+**Created:** 2026-08-11 19:35
+
+## Context
+
+This repo (`egress-proxies-operator`) has a Dockerfile, a Makefile with `docker-build`/`docker-push` targets, and a Gitea remote — but no CI workflow (CLAUDE.md flags this as a TODO). A survey of all projects under `/Users/jan.novak/srv` found 9 image-build workflows, all variations of one lineage: trigger on `workflow_dispatch` + tag push, `docker login` to `gitea.home.hrajfrisbee.cz` with `secrets.REGISTRY_TOKEN`, raw `docker build`/`docker push`, `runs-on: ubuntu-latest`, `permissions: {contents: read, packages: write}`.
+
+The best individual ideas are scattered:
+- **aviso_v2**: quality-gate job before build; computes `sha-<short>` as a second immutable tag via `$GITHUB_OUTPUT`.
+- **gateway-helper-operator** (closest sibling — same kubebuilder shape): passes build args (`GIT_COMMIT` etc.), tags `:latest` alongside the version tag.
+- **psmf-data-sync test.yaml**: `actions/setup-go@v5` with `go-version-file: go.mod` + module cache (proven to work on the act_runner).
+
+Goal: distill these into one `build.yaml` for this repo. User decisions: triggers = **tags + manual dispatch only** (house convention, no builds from main); build tool = **raw docker CLI** (the runner bind-mounts docker.sock, so this just works); **lightweight test gate** (`go vet` + `go build` + `go test -short`, no envtest download); **amd64 only**.
+
+## The workflow
+
+Create `.gitea/workflows/build.yaml`:
+
+```yaml
+name: Build and Push
+
+on:
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: 'Image tag'
+        required: true
+        default: 'latest'
+  push:
+    tags:
+      - '*'
+
+concurrency:
+  group: build-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+      - name: Vet
+        run: go vet ./...
+      - name: Build
+        run: go build ./...
+      - name: Test (short)
+        run: go test -short ./...
+
+  build:
+    needs: check
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Compute image tags
+        id: meta
+        run: |
+          if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
+            TAG="${{ inputs.tag }}"
+          else
+            TAG="${{ github.ref_name }}"
+          fi
+          echo "tag=$TAG" >> "$GITHUB_OUTPUT"
+          echo "sha=sha-$(echo '${{ github.sha }}' | cut -c1-12)" >> "$GITHUB_OUTPUT"
+
+      - name: Login to Gitea registry
+        run: echo "${{ secrets.REGISTRY_TOKEN }}" | docker login -u ${{ github.actor }} --password-stdin gitea.home.hrajfrisbee.cz
+
+      - name: Build and push
+        run: |
+          IMAGE=gitea.home.hrajfrisbee.cz/${{ github.repository }}
+          docker build \
+            --build-arg GIT_COMMIT=$(echo '${{ github.sha }}' | cut -c1-12) \
+            --label org.opencontainers.image.source=https://gitea.home.hrajfrisbee.cz/${{ github.repository }} \
+            --label org.opencontainers.image.created=$(date -u +%Y-%m-%dT%H:%M:%SZ) \
+            -t "$IMAGE:${{ steps.meta.outputs.tag }}" \
+            -t "$IMAGE:${{ steps.meta.outputs.sha }}" \
+            .
+          docker push "$IMAGE:${{ steps.meta.outputs.tag }}"
+          docker push "$IMAGE:${{ steps.meta.outputs.sha }}"
+
+      - name: Push latest (tag builds only)
+        if: github.event_name == 'push'
+        run: |
+          IMAGE=gitea.home.hrajfrisbee.cz/${{ github.repository }}
+          docker tag "$IMAGE:${{ steps.meta.outputs.tag }}" "$IMAGE:latest"
+          docker push "$IMAGE:latest"
+```
+
+### What's distilled vs. improved over the existing workflows
+
+Distilled (house patterns kept as-is): triggers, `REGISTRY_TOKEN` + `github.actor` login, image name `gitea.home.hrajfrisbee.cz/${{ github.repository }}`, `ubuntu-latest`, raw docker CLI, `permissions` block.
+
+Improvements none of the existing workflows have all of:
+1. **`sha-<12>` immutable tag** alongside the human tag (aviso_v2 had this; nobody else) — lets deployments pin exactly what was built.
+2. **Test gate** (aviso_v2 had one; the Go projects don't) — lightweight variant per user choice; uses `go-version-file: go.mod` so the Go version never drifts from the module.
+3. **`GIT_COMMIT` build arg** matches the Makefile/Dockerfile contract — the binary's `internal/version.Commit` and the `org.opencontainers.image.revision` label get the real commit (12-char, same width as the Makefile's `git rev-parse --short=12`; no `-dirty` needed since CI checkouts are clean).
+4. **`:latest` only on real tag pushes**, not manual dispatch — gateway-helper pushed `latest` unconditionally, which lets an ad-hoc dispatch of an old ref clobber `latest`.
+5. **`concurrency` group** — cancels a superseded run of the same ref (none of the 20 surveyed workflows have this).
+6. **OCI `source`/`created` labels** added at build time (revision label already comes from the Dockerfile).
+
+## Files
+
+- **Create** `.gitea/workflows/build.yaml` — content above.
+- **Update** `CLAUDE.md` — replace the `TODO: no .gitea/workflows/ CI pipeline exists yet` note in the Git Commits section with a short CI/CD subsection describing the workflow (triggers, secret, tags produced).
+- **Update** `CHANGELOG.md` — new top entry (after user confirms it works, per convention; timestamp via `date "+%Y-%m-%d %H:%M %Z"`).
+- Copy this plan to `docs/plans/YYYY-MM-DD-HHMM-gitea-build-workflow.md` (timestamp via `date "+%Y-%m-%d-%H%M"`) and commit it first, per CLAUDE.md ordering rule.
+
+## Branch & MR
+
+House convention: feature → own branch + MR. Dockerfile and `cmd/` already exist on `main`, so:
+
+1. `git checkout -b feat/gitea-build-workflow origin/main` (do not touch the current `feat/proxy-operator` branch's uncommitted `.claude/settings.json` change — leave it be).
+2. Commit plan file, then the workflow + CLAUDE.md update (with `Co-Authored-By: Claude <noreply@anthropic.com>`).
+3. `git push -u origin feat/gitea-build-workflow`, open MR with `tea pr create --base main --head feat/gitea-build-workflow`. Do not merge.
+
+Note: `main` has no `internal/`/`test/` dirs yet (those are on `feat/proxy-operator`), which is fine — the workflow only fires on tags/dispatch, and by then the operator branch will be merged. `go build ./...` / `go test -short ./...` work on both branch states.
+
+## Prerequisite (user action)
+
+`REGISTRY_TOKEN` secret must exist in this repo's Gitea settings (Settings → Actions → Secrets): a personal access token with `write:package` scope — same as every other project uses. Flag this in the MR description.
+
+## Verification
+
+The workflow doesn't trigger on branch pushes, so end-to-end verification happens after merge:
+1. Local sanity: `docker build --build-arg GIT_COMMIT=test -t scratch-check .` (confirms the build args/labels line is valid) — or at minimum a YAML parse check.
+2. After the MR merges: run the workflow manually via Gitea UI (Actions → Build and Push → Run workflow, tag `manual-test`), confirm both `manual-test` and `sha-…` tags appear under Packages, and that `:latest` was NOT updated.
+3. Then push a real version tag (e.g. `v0.1.0`) and confirm `v0.1.0`, `sha-…`, and `latest` all appear.