add env var to disable container image update checks (#2371)

agent/docker.go

@@ -68,10 +68,11 @@ type dockerManager struct {
 	excludeContainers    []string                    // Patterns to exclude containers by name
 	usingPodman          bool                        // Whether the Docker Engine API is running on Podman
 
-	registryClient      *http.Client                  // Client for registry requests; nil uses a client with a 10-second timeout
-	imageUpdatesMutex   sync.RWMutex                  // Protects imageUpdates, its entries, and imageUpdatesRunning
-	imageUpdates        map[string]*imageUpdateStatus // Shared update status keyed by normalized image reference
-	imageUpdatesRunning bool                          // Whether a background image-update batch is in progress
+	registryClient       *http.Client                  // Client for registry requests; nil uses a client with a 10-second timeout
+	imageUpdatesDisabled bool                          // Whether image update checks are disabled by configuration
+	imageUpdatesMutex    sync.RWMutex                  // Protects imageUpdates, its entries, and imageUpdatesRunning
+	imageUpdates         map[string]*imageUpdateStatus // Shared update status keyed by normalized image reference
+	imageUpdatesRunning  bool                          // Whether a background image-update batch is in progress
 
 	// Cache-time-aware tracking for CPU stats (similar to cpu.go)
 	// Maps cache time intervals to container-specific CPU usage tracking
@@ -688,6 +689,8 @@ func newDockerManager(agent *Agent) *dockerManager {
 		userAgent: "Docker-Client/",
 	}
 
+	dockerImageCheck, _ := utils.GetEnv("DOCKER_IMAGE_CHECK")
+
 	// Read container exclusion patterns from environment variable
 	var excludeContainers []string
 	if excludeStr, set := utils.GetEnv("EXCLUDE_CONTAINERS"); set && excludeStr != "" {
@@ -707,10 +710,11 @@ func newDockerManager(agent *Agent) *dockerManager {
 			Timeout:   timeout,
 			Transport: userAgentTransport,
 		},
-		containerStatsMap: make(map[string]*container.Stats),
-		sem:               make(chan struct{}, 5),
-		apiContainerList:  []*container.ApiInfo{},
-		excludeContainers: excludeContainers,
+		containerStatsMap:    make(map[string]*container.Stats),
+		sem:                  make(chan struct{}, 5),
+		apiContainerList:     []*container.ApiInfo{},
+		excludeContainers:    excludeContainers,
+		imageUpdatesDisabled: dockerImageCheck == "false",
 
 		// Initialize cache-time-aware tracking structures
 		lastCpuContainer:    make(map[uint16]map[string]uint64),

agent/docker_image_updates.go

@@ -31,6 +31,9 @@ func normalizedImageReference(image string) string {
 // refreshImageUpdates starts at most one background batch. Neither its network
 // work nor its completion is part of the container metrics wait group.
 func (dm *dockerManager) refreshImageUpdates(containers []*container.ApiInfo, now time.Time) {
+	if dm.imageUpdatesDisabled {
+		return
+	}
 	dm.imageUpdatesMutex.Lock()
 	defer dm.imageUpdatesMutex.Unlock()
 	if dm.imageUpdatesRunning {

agent/docker_image_updates_test.go

@@ -27,6 +27,29 @@ func waitForImageUpdates(t *testing.T, dm *dockerManager) {
 	}, time.Second*3, time.Millisecond)
 }
 
+func TestDisableDockerImageUpdateCheck(t *testing.T) {
+	t.Setenv("BESZEL_AGENT_DOCKER_IMAGE_CHECK", "false")
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/version" {
+			fmt.Fprint(w, `{"Version":"25.0.0"}`)
+			return
+		}
+		http.NotFound(w, r)
+	}))
+	defer server.Close()
+	t.Setenv("BESZEL_AGENT_DOCKER_HOST", server.URL)
+
+	dm := newDockerManager(nil)
+	require.True(t, dm.imageUpdatesDisabled)
+	dm.registryClient = &http.Client{Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
+		t.Fatal("disabled image update check made a registry request")
+		return nil, nil
+	})}
+	dm.refreshImageUpdates([]*container.ApiInfo{{Image: "nginx", Names: []string{"/nginx"}}}, time.Now())
+	require.False(t, dm.imageUpdatesRunning)
+	require.Nil(t, dm.imageUpdates)
+}
+
 func TestImageUpdateCacheAndStats(t *testing.T) {
 	local := "sha256:" + strings.Repeat("a", 64)
 	remote := "sha256:" + strings.Repeat("b", 64)