feat: add Prometheus metrics to listener service

Add an optional Prometheus metrics HTTP endpoint to the listener for monitoring deployment operations. Includes four metrics: - homelab_deploy_deployments_total (counter with status/action/error_code) - homelab_deploy_deployment_duration_seconds (histogram with action/success) - homelab_deploy_deployment_in_progress (gauge) - homelab_deploy_info (gauge with hostname/tier/role/version) New CLI flags: --metrics-enabled, --metrics-addr (default :9972) New NixOS options: metrics.enable, metrics.address, metrics.openFirewall Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2026-02-07 07:58:22 +01:00
parent 56365835c7
commit 79db119d1c
10 changed files with 613 additions and 9 deletions
--- a/internal/metrics/metrics_test.go
+++ b/internal/metrics/metrics_test.go
@@ -0,0 +1,210 @@
+package metrics
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+	"time"
+
+	"git.t-juice.club/torjus/homelab-deploy/internal/messages"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+func TestCollector_SetInfo(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	c := NewCollector(reg)
+
+	c.SetInfo("testhost", "test", "web", "1.0.0")
+
+	expected := `
+# HELP homelab_deploy_info Static instance metadata
+# TYPE homelab_deploy_info gauge
+homelab_deploy_info{hostname="testhost",role="web",tier="test",version="1.0.0"} 1
+`
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected), "homelab_deploy_info"); err != nil {
+		t.Errorf("unexpected metrics: %v", err)
+	}
+}
+
+func TestCollector_RecordDeploymentStart(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	c := NewCollector(reg)
+
+	c.RecordDeploymentStart()
+
+	expected := `
+# HELP homelab_deploy_deployment_in_progress 1 if deployment running, 0 otherwise
+# TYPE homelab_deploy_deployment_in_progress gauge
+homelab_deploy_deployment_in_progress 1
+`
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected), "homelab_deploy_deployment_in_progress"); err != nil {
+		t.Errorf("unexpected metrics: %v", err)
+	}
+}
+
+func TestCollector_RecordDeploymentEnd_Success(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	c := NewCollector(reg)
+
+	c.RecordDeploymentStart()
+	c.RecordDeploymentEnd(messages.ActionSwitch, true, 120.5)
+
+	// Check in_progress is 0
+	inProgressExpected := `
+# HELP homelab_deploy_deployment_in_progress 1 if deployment running, 0 otherwise
+# TYPE homelab_deploy_deployment_in_progress gauge
+homelab_deploy_deployment_in_progress 0
+`
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(inProgressExpected), "homelab_deploy_deployment_in_progress"); err != nil {
+		t.Errorf("unexpected in_progress metrics: %v", err)
+	}
+
+	// Check counter incremented
+	counterExpected := `
+# HELP homelab_deploy_deployments_total Total deployment requests processed
+# TYPE homelab_deploy_deployments_total counter
+homelab_deploy_deployments_total{action="switch",error_code="",status="completed"} 1
+`
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(counterExpected), "homelab_deploy_deployments_total"); err != nil {
+		t.Errorf("unexpected counter metrics: %v", err)
+	}
+}
+
+func TestCollector_RecordDeploymentEnd_Failure(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	c := NewCollector(reg)
+
+	c.RecordDeploymentStart()
+	c.RecordDeploymentEnd(messages.ActionBoot, false, 60.0)
+
+	counterExpected := `
+# HELP homelab_deploy_deployments_total Total deployment requests processed
+# TYPE homelab_deploy_deployments_total counter
+homelab_deploy_deployments_total{action="boot",error_code="",status="failed"} 1
+`
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(counterExpected), "homelab_deploy_deployments_total"); err != nil {
+		t.Errorf("unexpected counter metrics: %v", err)
+	}
+}
+
+func TestCollector_RecordDeploymentFailure(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	c := NewCollector(reg)
+
+	c.RecordDeploymentStart()
+	c.RecordDeploymentFailure(messages.ActionSwitch, messages.ErrorBuildFailed, 300.0)
+
+	counterExpected := `
+# HELP homelab_deploy_deployments_total Total deployment requests processed
+# TYPE homelab_deploy_deployments_total counter
+homelab_deploy_deployments_total{action="switch",error_code="build_failed",status="failed"} 1
+`
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(counterExpected), "homelab_deploy_deployments_total"); err != nil {
+		t.Errorf("unexpected counter metrics: %v", err)
+	}
+}
+
+func TestCollector_RecordRejection(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	c := NewCollector(reg)
+
+	c.RecordRejection(messages.ActionSwitch, messages.ErrorAlreadyRunning)
+
+	expected := `
+# HELP homelab_deploy_deployments_total Total deployment requests processed
+# TYPE homelab_deploy_deployments_total counter
+homelab_deploy_deployments_total{action="switch",error_code="already_running",status="rejected"} 1
+`
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected), "homelab_deploy_deployments_total"); err != nil {
+		t.Errorf("unexpected metrics: %v", err)
+	}
+}
+
+func TestServer_StartShutdown(t *testing.T) {
+	srv := NewServer(ServerConfig{
+		Addr: ":0", // Let OS pick a free port
+	})
+
+	if err := srv.Start(); err != nil {
+		t.Fatalf("failed to start server: %v", err)
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	if err := srv.Shutdown(ctx); err != nil {
+		t.Errorf("failed to shutdown server: %v", err)
+	}
+}
+
+func TestServer_Endpoints(t *testing.T) {
+	srv := NewServer(ServerConfig{
+		Addr: "127.0.0.1:19972", // Use a fixed port for testing
+	})
+
+	if err := srv.Start(); err != nil {
+		t.Fatalf("failed to start server: %v", err)
+	}
+
+	defer func() {
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		_ = srv.Shutdown(ctx)
+	}()
+
+	// Give server time to start
+	time.Sleep(50 * time.Millisecond)
+
+	t.Run("health endpoint", func(t *testing.T) {
+		resp, err := http.Get("http://127.0.0.1:19972/health")
+		if err != nil {
+			t.Fatalf("failed to get health endpoint: %v", err)
+		}
+		defer func() { _ = resp.Body.Close() }()
+
+		if resp.StatusCode != http.StatusOK {
+			t.Errorf("expected status 200, got %d", resp.StatusCode)
+		}
+
+		body, _ := io.ReadAll(resp.Body)
+		if string(body) != "ok" {
+			t.Errorf("expected body 'ok', got %q", string(body))
+		}
+	})
+
+	t.Run("metrics endpoint", func(t *testing.T) {
+		// Set some info to have metrics to display
+		srv.Collector().SetInfo("testhost", "test", "web", "1.0.0")
+
+		resp, err := http.Get("http://127.0.0.1:19972/metrics")
+		if err != nil {
+			t.Fatalf("failed to get metrics endpoint: %v", err)
+		}
+		defer func() { _ = resp.Body.Close() }()
+
+		if resp.StatusCode != http.StatusOK {
+			t.Errorf("expected status 200, got %d", resp.StatusCode)
+		}
+
+		body, _ := io.ReadAll(resp.Body)
+		bodyStr := string(body)
+
+		if !strings.Contains(bodyStr, "homelab_deploy_info") {
+			t.Error("expected metrics to contain homelab_deploy_info")
+		}
+	})
+}
+
+func TestServer_Collector(t *testing.T) {
+	srv := NewServer(ServerConfig{
+		Addr: ":0",
+	})
+
+	collector := srv.Collector()
+	if collector == nil {
+		t.Error("expected non-nil collector")
+	}
+}