feat(oidcgate): healthz and readyz endpoints

cmd/oidcgate/health.go

@@ -0,0 +1,24 @@
+package main
+
+import "net/http"
+
+// readyReporter is satisfied by *traefikoidc.TraefikOidc via its Ready() method.
+type readyReporter interface {
+	Ready() bool
+}
+
+func newHealthzHandler() http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, _ *http.Request) {
+		rw.WriteHeader(http.StatusOK)
+	})
+}
+
+func newReadyzHandler(r readyReporter) http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, _ *http.Request) {
+		if r.Ready() {
+			rw.WriteHeader(http.StatusOK)
+			return
+		}
+		rw.WriteHeader(http.StatusServiceUnavailable)
+	})
+}

cmd/oidcgate/health_test.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+type readyStub struct{ ready bool }
+
+func (r *readyStub) Ready() bool { return r.ready }
+
+func TestHealthz_Always200(t *testing.T) {
+	h := newHealthzHandler()
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/healthz", nil))
+	if rec.Code != http.StatusOK {
+		t.Fatalf("healthz: want 200, got %d", rec.Code)
+	}
+}
+
+func TestReadyz_503BeforeDiscovery(t *testing.T) {
+	h := newReadyzHandler(&readyStub{ready: false})
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/readyz", nil))
+	if rec.Code != http.StatusServiceUnavailable {
+		t.Fatalf("readyz pre-discovery: want 503, got %d", rec.Code)
+	}
+}
+
+func TestReadyz_200AfterDiscovery(t *testing.T) {
+	h := newReadyzHandler(&readyStub{ready: true})
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/readyz", nil))
+	if rec.Code != http.StatusOK {
+		t.Fatalf("readyz post-discovery: want 200, got %d", rec.Code)
+	}
+}