Add plan: bake git commit into the operator binary and log it at startup

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

docs/plans/2026-08-11-1802-bake-commit-version.md

@@ -0,0 +1,75 @@
+# Plan: Bake the git commit into the operator binary and log it at startup
+
+**Created:** 2026-08-11 18:02
+
+## Context
+
+There is no versioning yet, and the image tag (`egress-proxies-operator:dev`,
+`imagePullPolicy: IfNotPresent`) says nothing about what code is actually
+running. The user wants the commit hash baked into the image at build time,
+and — the key requirement — the binary itself must know it and print it into
+the log stream during initialization, so `kubectl logs | head` answers "which
+version is running". Docker builds cannot use Go's automatic VCS stamp because
+`.dockerignore` excludes `.git` (correctly — re-including it would bust layer
+caching), so the hash must travel git → Makefile → `--build-arg` → `-ldflags -X`.
+
+## Implementation
+
+**1. New package `internal/version`** (`version.go` + `version_test.go`):
+
+- `var Commit string` — stamped at link time via
+  `-ldflags "-X gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/version.Commit=<hash>"`.
+- `func Resolve() string` — returns `Commit` if non-empty; otherwise falls
+  back to `debug.ReadBuildInfo()` VCS settings (`vcs.revision` truncated to
+  12 chars, `-dirty` suffix when `vcs.modified=true`), so plain host builds
+  (`make build`, `make run`, `go run`) are stamped for free since `.git` is
+  present there; `"unknown"` when neither source is available (e.g. `go test`).
+- Internal `resolve(ldflagsCommit string, readBuildInfo func() (*debug.BuildInfo, bool)) string`
+  so the fallback logic is table-testable with a fake build-info func
+  (house style: stdlib testing, `t.Parallel()`, subtests,
+  `Test<Function>_<scenario>` names).
+
+**2. `cmd/main.go`**:
+
+- Add `--version` bool flag; immediately after the existing `flag.Parse()`
+  (main.go:132), if set: print `version.Resolve()` to stdout and exit 0
+  (before logger/manager setup).
+- Right after `ctrl.SetLogger(...)` (main.go:134):
+  `setupLog.Info("Starting egress-proxies-operator", "commit", version.Resolve(), "goVersion", runtime.Version())`
+  — first line of every run, plain V(0) so it appears at any log level.
+
+**3. `Makefile`**:
+
+- Near the other variables:
+  `GIT_COMMIT ?= $(shell git rev-parse --short=12 HEAD 2>/dev/null || echo unknown)$(shell test -z "$$(git status --porcelain 2>/dev/null)" || echo -dirty)`
+  (`git status --porcelain` catches staged and untracked changes, which
+  `git diff --quiet` misses).
+- `docker-build`: add `--build-arg GIT_COMMIT=$(GIT_COMMIT)`.
+- `docker-buildx`: add the same `--build-arg` to the `buildx build` line.
+- `build`/`run`/`run-dev` stay untouched — the ReadBuildInfo fallback covers them.
+
+**4. `Dockerfile`**:
+
+- `ARG GIT_COMMIT=unknown` in the builder stage; extend the existing
+  `go build` with `-ldflags "-X <module>/internal/version.Commit=${GIT_COMMIT}"`.
+- Re-declare `ARG GIT_COMMIT` in the distroless stage and add
+  `LABEL org.opencontainers.image.revision="${GIT_COMMIT}"` so the hash is
+  also visible via `docker inspect` without running the binary.
+
+No changes to deploy manifests, providers, or the reconciler. CHANGELOG entry
+after the user confirms it works (house convention).
+
+## Verification
+
+```bash
+go test ./internal/version/            # resolve() table tests
+go build ./... && go test ./...        # nothing else broke
+go run ./cmd/main.go --version         # host build: VCS-stamped hash (+ -dirty), exit 0
+make docker-build IMG=egress-proxies-operator:dev
+docker run --rm egress-proxies-operator:dev --version          # prints the baked commit
+docker inspect egress-proxies-operator:dev \
+  --format '{{index .Config.Labels "org.opencontainers.image.revision"}}'
+```
+
+Live check: redeploy on the cluster and confirm the first log line carries
+`"commit"`.