Dockerfile

@@ -2,6 +2,7 @@
 FROM golang:1.26 AS builder
 ARG TARGETOS
 ARG TARGETARCH
+ARG GIT_COMMIT=unknown
 
 WORKDIR /workspace
 # Copy the Go Modules manifests
@@ -19,11 +20,15 @@ COPY . .
 # was called. For example, if we call make docker-build in a local env which has the Apple Silicon M1 SO
 # the docker BUILDPLATFORM arg will be linux/arm64 when for Apple x86 it will be linux/amd64. Therefore,
 # by leaving it empty we can ensure that the container and binary shipped on it will have the same platform.
-RUN CGO_ENABLED=0 GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} go build -a -o manager cmd/main.go
+RUN CGO_ENABLED=0 GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} go build -a \
+    -ldflags "-X gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/version.Commit=${GIT_COMMIT}" \
+    -o manager cmd/main.go
 
 # Use distroless as minimal base image to package the manager binary
 # Refer to https://github.com/GoogleContainerTools/distroless for more details
 FROM gcr.io/distroless/static:nonroot
+ARG GIT_COMMIT=unknown
+LABEL org.opencontainers.image.revision="${GIT_COMMIT}"
 WORKDIR /
 COPY --from=builder /workspace/manager .
 USER 65532:65532

Makefile

@@ -2,6 +2,9 @@
 IMG ?= controller:latest
 # YEAR defines the year value used for substituting the YEAR placeholder in the boilerplate header.
 YEAR ?= $(shell date +%Y)
+# GIT_COMMIT is baked into the image (-ldflags in the Dockerfile); -dirty
+# covers staged and untracked changes too, which `git diff --quiet` misses.
+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)
 
 # Get the currently used golang install path (in GOPATH/bin, unless GOBIN is set)
 ifeq (,$(shell go env GOBIN))
@@ -110,7 +113,7 @@ lint-config: golangci-lint ## Verify golangci-lint linter configuration
 
 .PHONY: build
 build: manifests generate fmt vet ## Build manager binary.
-	go build -o bin/manager cmd/main.go
+	go build -o bin/manager ./cmd
 
 .PHONY: run
 run: manifests generate fmt vet ## Run a controller from your host.
@@ -125,7 +128,7 @@ run-dev: manifests generate fmt vet ## Run locally against the current kubeconfi
 # More info: https://docs.docker.com/develop/develop-images/build_enhancements/
 .PHONY: docker-build
 docker-build: ## Build docker image with the manager.
-	$(CONTAINER_TOOL) build -t ${IMG} .
+	$(CONTAINER_TOOL) build --build-arg GIT_COMMIT=$(GIT_COMMIT) -t ${IMG} .
 
 .PHONY: docker-push
 docker-push: ## Push docker image with the manager.
@@ -144,7 +147,7 @@ docker-buildx: ## Build and push docker image for the manager for cross-platform
 	sed -e '1 s/\(^FROM\)/FROM --platform=\$$\{BUILDPLATFORM\}/; t' -e ' 1,// s//FROM --platform=\$$\{BUILDPLATFORM\}/' Dockerfile > Dockerfile.cross
 	- $(CONTAINER_TOOL) buildx create --name egress-proxies-operator-builder
 	$(CONTAINER_TOOL) buildx use egress-proxies-operator-builder
-	- $(CONTAINER_TOOL) buildx build --push --platform=$(PLATFORMS) --tag ${IMG} -f Dockerfile.cross .
+	- $(CONTAINER_TOOL) buildx build --push --platform=$(PLATFORMS) --build-arg GIT_COMMIT=$(GIT_COMMIT) --tag ${IMG} -f Dockerfile.cross .
 	- $(CONTAINER_TOOL) buildx rm egress-proxies-operator-builder
 	rm Dockerfile.cross
 

cmd/main.go

@@ -24,7 +24,9 @@ import (
 	"context"
 	"crypto/tls"
 	"flag"
+	"fmt"
 	"os"
+	goruntime "runtime"
 	"time"
 
 	// Import all Kubernetes client auth plugins (e.g. Azure, GCP, OIDC, etc.)
@@ -56,6 +58,7 @@ import (
 	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider/gcp"
 	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider/kubernetes"
 	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider/registry"
+	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/version"
 	// +kubebuilder:scaffold:imports
 )
 
@@ -88,6 +91,7 @@ func main() {
 	var gcInterval, gcMinAge time.Duration
 	var gcAllowNamespaced bool
 	var leaseCooldown, maxLeaseTTL time.Duration
+	var showVersion bool
 
 	flag.StringVar(&metricsAddr, "metrics-bind-address", "0", "The address the metrics endpoint binds to. "+
 		"Use :8443 for HTTPS or :8080 for HTTP, or leave as 0 to disable the metrics service.")
@@ -124,6 +128,8 @@ func main() {
 		"How long a reported proxy/target pair is excluded from lease selection.")
 	flag.DurationVar(&maxLeaseTTL, "max-lease-ttl", time.Hour,
 		"Maximum lease TTL a client may request.")
+	flag.BoolVar(&showVersion, "version", false,
+		"Print the commit the binary was built from and exit.")
 
 	opts := zap.Options{
 		Development: true,
@@ -131,7 +137,14 @@ func main() {
 	opts.BindFlags(flag.CommandLine)
 	flag.Parse()
 
+	if showVersion {
+		fmt.Println(version.Resolve())
+		os.Exit(0)
+	}
+
 	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
+	setupLog.Info("Starting egress-proxies-operator",
+		"commit", version.Resolve(), "goVersion", goruntime.Version())
 	ctx := ctrl.SetupSignalHandler()
 
 	// Providers load first and fail fast: a manager that comes up without

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

@@ -0,0 +1,62 @@
+# Execution: Bake the git commit into the operator binary and log it at startup
+
+Plan: `docs/plans/2026-08-11-1802-bake-commit-version.md`
+
+- [x] Step 0 — Save and commit the plan
+- [x] Step 1 — `internal/version` package + tests
+- [x] Step 2 — `cmd/main.go`: `--version` flag + startup log line
+- [x] Step 3 — Makefile `GIT_COMMIT` + `--build-arg` wiring
+- [x] Step 4 — Dockerfile `-ldflags` stamp + OCI revision label
+- [ ] Step 5 — CHANGELOG entry (after the user confirms it works live)
+
+## Steps 1–4
+
+Mostly as planned. One deviation worth recording: the plan claimed
+`build`/`run` targets need no changes because Go's automatic VCS stamp covers
+host builds — that turned out to be only half true. Go skips VCS stamping
+when the build target is a *file argument* rather than a package pattern, and
+the Makefile's `build` target used `go build -o bin/manager cmd/main.go`.
+Verified empirically:
+
+```bash
+go build -o bin/manager cmd/main.go && ./bin/manager --version   # unknown (no vcs settings)
+go build -o bin/manager ./cmd       && ./bin/manager --version   # e4d2a191d0c2-dirty
+```
+
+So `build:` now uses `go build -o bin/manager ./cmd`. `go run` never stamps
+VCS info regardless of invocation form — `make run`/`run-dev` print
+`commit=unknown`, which is acceptable for dev loops (the Dockerfile path uses
+the explicit ldflags stamp and is unaffected; it kept `cmd/main.go`).
+
+The ldflags path was verified independently:
+
+```bash
+go build -ldflags "-X gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/version.Commit=deadbeef1234" \
+  -o bin/manager-stamped cmd/main.go
+./bin/manager-stamped --version   # deadbeef1234
+```
+
+Worth noting: `cmd/main.go` imports k8s apimachinery as `runtime`, so the
+stdlib runtime needed an alias (`goruntime "runtime"`) for
+`goruntime.Version()` in the startup line. The `--version` check happens
+right after `flag.Parse()`, before logger and manager setup, so it works
+without a kubeconfig.
+
+## Verification
+
+```bash
+go vet ./... && go test ./...           # all green, incl. new resolve() table tests
+go build -o bin/manager ./cmd && ./bin/manager --version   # e4d2a191d0c2-dirty
+```
+
+The image-level check could not run locally — the Docker daemon was not
+running. `make docker-build IMG=egress-proxies-operator:dev` did prove the
+Makefile side before failing at the daemon: it invoked
+`docker build --build-arg GIT_COMMIT=e4d2a191d0c2-dirty ...`. Still pending
+(needs a running daemon):
+
+```bash
+make docker-build IMG=egress-proxies-operator:dev
+docker run --rm egress-proxies-operator:dev --version
+docker inspect egress-proxies-operator:dev --format '{{index .Config.Labels "org.opencontainers.image.revision"}}'
+```

internal/version/version.go

@@ -0,0 +1,47 @@
+// Package version reports which commit the binary was built from. Docker
+// builds stamp it via -ldflags (the build context has no .git, so Go's
+// automatic VCS stamp is absent there); host builds fall back to that
+// automatic stamp.
+package version
+
+import "runtime/debug"
+
+// Commit is set at link time via
+// -ldflags "-X <module>/internal/version.Commit=<hash>".
+var Commit string
+
+// Resolve returns the commit the binary was built from, or "unknown" when
+// neither the ldflags stamp nor build info is available (e.g. go test).
+func Resolve() string {
+	return resolve(Commit, debug.ReadBuildInfo)
+}
+
+func resolve(ldflagsCommit string, readBuildInfo func() (*debug.BuildInfo, bool)) string {
+	if ldflagsCommit != "" {
+		return ldflagsCommit
+	}
+	bi, ok := readBuildInfo()
+	if !ok {
+		return "unknown"
+	}
+	var revision string
+	var modified bool
+	for _, s := range bi.Settings {
+		switch s.Key {
+		case "vcs.revision":
+			revision = s.Value
+		case "vcs.modified":
+			modified = s.Value == "true"
+		}
+	}
+	if revision == "" {
+		return "unknown"
+	}
+	if len(revision) > 12 {
+		revision = revision[:12]
+	}
+	if modified {
+		revision += "-dirty"
+	}
+	return revision
+}

internal/version/version_test.go

@@ -0,0 +1,74 @@
+package version
+
+import (
+	"runtime/debug"
+	"testing"
+)
+
+func buildInfoWith(settings ...debug.BuildSetting) func() (*debug.BuildInfo, bool) {
+	return func() (*debug.BuildInfo, bool) {
+		return &debug.BuildInfo{Settings: settings}, true
+	}
+}
+
+func TestResolve_precedenceAndFallback(t *testing.T) {
+	t.Parallel()
+
+	noBuildInfo := func() (*debug.BuildInfo, bool) { return nil, false }
+
+	tests := []struct {
+		name          string
+		ldflagsCommit string
+		readBuildInfo func() (*debug.BuildInfo, bool)
+		want          string
+	}{
+		{
+			name:          "ldflags stamp wins over build info",
+			ldflagsCommit: "abc123def456-dirty",
+			readBuildInfo: buildInfoWith(debug.BuildSetting{Key: "vcs.revision", Value: "ffffffffffffffffffffffffffffffffffffffff"}),
+			want:          "abc123def456-dirty",
+		},
+		{
+			name:          "no stamp, no build info",
+			readBuildInfo: noBuildInfo,
+			want:          "unknown",
+		},
+		{
+			name:          "build info without vcs settings",
+			readBuildInfo: buildInfoWith(),
+			want:          "unknown",
+		},
+		{
+			name: "full revision truncated to 12 chars",
+			readBuildInfo: buildInfoWith(
+				debug.BuildSetting{Key: "vcs.revision", Value: "0123456789abcdef0123456789abcdef01234567"},
+				debug.BuildSetting{Key: "vcs.modified", Value: "false"},
+			),
+			want: "0123456789ab",
+		},
+		{
+			name: "modified tree gets dirty suffix",
+			readBuildInfo: buildInfoWith(
+				debug.BuildSetting{Key: "vcs.revision", Value: "0123456789abcdef0123456789abcdef01234567"},
+				debug.BuildSetting{Key: "vcs.modified", Value: "true"},
+			),
+			want: "0123456789ab-dirty",
+		},
+		{
+			name: "short revision kept as-is",
+			readBuildInfo: buildInfoWith(
+				debug.BuildSetting{Key: "vcs.revision", Value: "abc123"},
+			),
+			want: "abc123",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			if got := resolve(tc.ldflagsCommit, tc.readBuildInfo); got != tc.want {
+				t.Errorf("resolve() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}