agent: detect podman correctly when using socket proxy (#1846)

agent/agent.go

@@ -19,6 +19,8 @@ import (
 	gossh "golang.org/x/crypto/ssh"
 )
 
+const defaultDataCacheTimeMs uint16 = 60_000
+
 type Agent struct {
 	sync.Mutex                                                                      // Used to lock agent while collecting data
 	debug                     bool                                                  // true if LOG_LEVEL is set to debug
@@ -36,6 +38,7 @@ type Agent struct {
 	sensorConfig              *SensorConfig                                         // Sensors config
 	systemInfo                system.Info                                           // Host system info (dynamic)
 	systemDetails             system.Details                                        // Host system details (static, once-per-connection)
+	detailsDirty              bool                                                  // Whether system details have changed and need to be resent
 	gpuManager                *GPUManager                                           // Manages GPU data
 	cache                     *systemDataCache                                      // Cache for system stats based on cache time
 	connectionManager         *ConnectionManager                                    // Channel to signal connection events
@@ -97,7 +100,7 @@ func NewAgent(dataDir ...string) (agent *Agent, err error) {
 	slog.Debug(beszel.Version)
 
 	// initialize docker manager
-	agent.dockerManager = newDockerManager()
+	agent.dockerManager = newDockerManager(agent)
 
 	// initialize system info
 	agent.refreshSystemDetails()
@@ -142,7 +145,7 @@ func NewAgent(dataDir ...string) (agent *Agent, err error) {
 
 	// if debugging, print stats
 	if agent.debug {
-		slog.Debug("Stats", "data", agent.gatherStats(common.DataRequestOptions{CacheTimeMs: 60_000, IncludeDetails: true}))
+		slog.Debug("Stats", "data", agent.gatherStats(common.DataRequestOptions{CacheTimeMs: defaultDataCacheTimeMs, IncludeDetails: true}))
 	}
 
 	return agent, nil
@@ -164,11 +167,6 @@ func (a *Agent) gatherStats(options common.DataRequestOptions) *system.CombinedD
 		Info:  a.systemInfo,
 	}
 
-	// Include static system details only when requested
-	if options.IncludeDetails {
-		data.Details = &a.systemDetails
-	}
-
 	// slog.Info("System data", "data", data, "cacheTimeMs", cacheTimeMs)
 
 	if a.dockerManager != nil {
@@ -181,7 +179,7 @@ func (a *Agent) gatherStats(options common.DataRequestOptions) *system.CombinedD
 	}
 
 	// skip updating systemd services if cache time is not the default 60sec interval
-	if a.systemdManager != nil && cacheTimeMs == 60_000 {
+	if a.systemdManager != nil && cacheTimeMs == defaultDataCacheTimeMs {
 		totalCount := uint16(a.systemdManager.getServiceStatsCount())
 		if totalCount > 0 {
 			numFailed := a.systemdManager.getFailedServiceCount()
@@ -212,7 +210,8 @@ func (a *Agent) gatherStats(options common.DataRequestOptions) *system.CombinedD
 	slog.Debug("Extra FS", "data", data.Stats.ExtraFs)
 
 	a.cache.Set(data, cacheTimeMs)
-	return data
+
+	return a.attachSystemDetails(data, cacheTimeMs, options.IncludeDetails)
 }
 
 // Start initializes and starts the agent with optional WebSocket connection

agent/docker.go

@@ -25,6 +25,7 @@ import (
 	"github.com/henrygd/beszel/agent/deltatracker"
 	"github.com/henrygd/beszel/agent/utils"
 	"github.com/henrygd/beszel/internal/entities/container"
+	"github.com/henrygd/beszel/internal/entities/system"
 
 	"github.com/blang/semver"
 )
@@ -52,20 +53,22 @@ const (
 )
 
 type dockerManager struct {
-	client              *http.Client                // Client to query Docker API
+	agent                *Agent                      // Used to propagate system detail changes back to the agent
-	wg                  sync.WaitGroup              // WaitGroup to wait for all goroutines to finish
+	client               *http.Client                // Client to query Docker API
-	sem                 chan struct{}               // Semaphore to limit concurrent container requests
+	wg                   sync.WaitGroup              // WaitGroup to wait for all goroutines to finish
-	containerStatsMutex sync.RWMutex                // Mutex to prevent concurrent access to containerStatsMap
+	sem                  chan struct{}               // Semaphore to limit concurrent container requests
-	apiContainerList    []*container.ApiInfo        // List of containers from Docker API
+	containerStatsMutex  sync.RWMutex                // Mutex to prevent concurrent access to containerStatsMap
-	containerStatsMap   map[string]*container.Stats // Keeps track of container stats
+	apiContainerList     []*container.ApiInfo        // List of containers from Docker API
-	validIds            map[string]struct{}         // Map of valid container ids, used to prune invalid containers from containerStatsMap
+	containerStatsMap    map[string]*container.Stats // Keeps track of container stats
-	goodDockerVersion   bool                        // Whether docker version is at least 25.0.0 (one-shot works correctly)
+	validIds             map[string]struct{}         // Map of valid container ids, used to prune invalid containers from containerStatsMap
-	isWindows           bool                        // Whether the Docker Engine API is running on Windows
+	goodDockerVersion    bool                        // Whether docker version is at least 25.0.0 (one-shot works correctly)
-	buf                 *bytes.Buffer               // Buffer to store and read response bodies
+	dockerVersionChecked bool                        // Whether a version probe has completed successfully
-	decoder             *json.Decoder               // Reusable JSON decoder that reads from buf
+	isWindows            bool                        // Whether the Docker Engine API is running on Windows
-	apiStats            *container.ApiStats         // Reusable API stats object
+	buf                  *bytes.Buffer               // Buffer to store and read response bodies
-	excludeContainers   []string                    // Patterns to exclude containers by name
+	decoder              *json.Decoder               // Reusable JSON decoder that reads from buf
-	usingPodman         bool                        // Whether the Docker Engine API is running on Podman
+	apiStats             *container.ApiStats         // Reusable API stats object
+	excludeContainers    []string                    // Patterns to exclude containers by name
+	usingPodman          bool                        // Whether the Docker Engine API is running on Podman
 
 	// Cache-time-aware tracking for CPU stats (similar to cpu.go)
 	// Maps cache time intervals to container-specific CPU usage tracking
@@ -78,7 +81,6 @@ type dockerManager struct {
 	networkSentTrackers map[uint16]*deltatracker.DeltaTracker[string, uint64]
 	networkRecvTrackers map[uint16]*deltatracker.DeltaTracker[string, uint64]
 	lastNetworkReadTime map[uint16]map[string]time.Time // cacheTimeMs -> containerId -> last network read time
-	retrySleep          func(time.Duration)
 }
 
 // userAgentRoundTripper is a custom http.RoundTripper that adds a User-Agent header to all requests
@@ -87,6 +89,14 @@ type userAgentRoundTripper struct {
 	userAgent string
 }
 
+// dockerVersionResponse contains the /version fields used for engine checks.
+type dockerVersionResponse struct {
+	Version    string `json:"Version"`
+	Components []struct {
+		Name string `json:"Name"`
+	} `json:"Components"`
+}
+
 // RoundTrip implements the http.RoundTripper interface
 func (u *userAgentRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
 	req.Header.Set("User-Agent", u.userAgent)
@@ -134,7 +144,14 @@ func (dm *dockerManager) getDockerStats(cacheTimeMs uint16) ([]*container.Stats,
 		return nil, err
 	}
 
-	dm.isWindows = strings.Contains(resp.Header.Get("Server"), "windows")
+	// Detect Podman and Windows from Server header
+	serverHeader := resp.Header.Get("Server")
+	if !dm.usingPodman && detectPodmanFromHeader(serverHeader) {
+		dm.setIsPodman()
+	}
+	dm.isWindows = strings.Contains(serverHeader, "windows")
+
+	dm.ensureDockerVersionChecked()
 
 	containersLength := len(dm.apiContainerList)
 
@@ -588,7 +605,7 @@ func (dm *dockerManager) deleteContainerStatsSync(id string) {
 }
 
 // Creates a new http client for Docker or Podman API
-func newDockerManager() *dockerManager {
+func newDockerManager(agent *Agent) *dockerManager {
 	dockerHost, exists := utils.GetEnv("DOCKER_HOST")
 	if exists {
 		// return nil if set to empty string
@@ -654,6 +671,7 @@ func newDockerManager() *dockerManager {
 	}
 
 	manager := &dockerManager{
+		agent: agent,
 		client: &http.Client{
 			Timeout:   timeout,
 			Transport: userAgentTransport,
@@ -671,51 +689,54 @@ func newDockerManager() *dockerManager {
 		networkSentTrackers: make(map[uint16]*deltatracker.DeltaTracker[string, uint64]),
 		networkRecvTrackers: make(map[uint16]*deltatracker.DeltaTracker[string, uint64]),
 		lastNetworkReadTime: make(map[uint16]map[string]time.Time),
-		retrySleep:          time.Sleep,
 	}
 
-	// If using podman, return client
+	// Best-effort startup probe. If the engine is not ready yet, getDockerStats will
-	if strings.Contains(dockerHost, "podman") {
+	// retry after the first successful /containers/json request.
-		manager.usingPodman = true
+	_, _ = manager.checkDockerVersion()
-		manager.goodDockerVersion = true
-		return manager
-	}
-
-	// run version check in goroutine to avoid blocking (server may not be ready and requires retries)
-	go manager.checkDockerVersion()
-
-	// give version check a chance to complete before returning
-	time.Sleep(50 * time.Millisecond)
 
 	return manager
 }
 
 // checkDockerVersion checks Docker version and sets goodDockerVersion if at least 25.0.0.
 // Versions before 25.0.0 have a bug with one-shot which requires all requests to be made in one batch.
-func (dm *dockerManager) checkDockerVersion() {
+func (dm *dockerManager) checkDockerVersion() (bool, error) {
-	var err error
+	resp, err := dm.client.Get("http://localhost/version")
-	var resp *http.Response
+	if err != nil {
-	var versionInfo struct {
+		return false, err
-		Version string `json:"Version"`
 	}
-	const versionMaxTries = 2
+	if resp.StatusCode != http.StatusOK {
-	for i := 1; i <= versionMaxTries; i++ {
+		status := resp.Status
-		resp, err = dm.client.Get("http://localhost/version")
+		resp.Body.Close()
-		if err == nil && resp.StatusCode == http.StatusOK {
+		return false, fmt.Errorf("docker version request failed: %s", status)
-			break
-		}
-		if resp != nil {
-			resp.Body.Close()
-		}
-		if i < versionMaxTries {
-			slog.Debug("Failed to get Docker version; retrying", "attempt", i, "err", err, "response", resp)
-			dm.retrySleep(5 * time.Second)
-		}
 	}
-	if err != nil || resp.StatusCode != http.StatusOK {
+
+	var versionInfo dockerVersionResponse
+	serverHeader := resp.Header.Get("Server")
+	if err := dm.decode(resp, &versionInfo); err != nil {
+		return false, err
+	}
+
+	dm.applyDockerVersionInfo(serverHeader, &versionInfo)
+	dm.dockerVersionChecked = true
+	return true, nil
+}
+
+// ensureDockerVersionChecked retries the version probe after a successful
+// container list request.
+func (dm *dockerManager) ensureDockerVersionChecked() {
+	if dm.dockerVersionChecked {
 		return
 	}
-	if err := dm.decode(resp, &versionInfo); err != nil {
+	if _, err := dm.checkDockerVersion(); err != nil {
+		slog.Debug("Failed to get Docker version", "err", err)
+	}
+}
+
+// applyDockerVersionInfo updates version-dependent behavior from engine metadata.
+func (dm *dockerManager) applyDockerVersionInfo(serverHeader string, versionInfo *dockerVersionResponse) {
+	if detectPodmanEngine(serverHeader, versionInfo) {
+		dm.setIsPodman()
 		return
 	}
 	// if version > 24, one-shot works correctly and we can limit concurrent operations
@@ -941,3 +962,46 @@ func (dm *dockerManager) GetHostInfo() (info container.HostInfo, err error) {
 func (dm *dockerManager) IsPodman() bool {
 	return dm.usingPodman
 }
+
+// setIsPodman sets the manager to Podman mode and updates system details accordingly.
+func (dm *dockerManager) setIsPodman() {
+	if dm.usingPodman {
+		return
+	}
+	dm.usingPodman = true
+	dm.goodDockerVersion = true
+	dm.dockerVersionChecked = true
+	// keep system details updated - this may be detected late if server isn't ready when
+	// agent starts, so make sure we notify the hub if this happens later.
+	if dm.agent != nil {
+		dm.agent.updateSystemDetails(func(details *system.Details) {
+			details.Podman = true
+		})
+	}
+}
+
+// detectPodmanFromHeader identifies Podman from the Docker API server header.
+func detectPodmanFromHeader(server string) bool {
+	return strings.HasPrefix(server, "Libpod")
+}
+
+// detectPodmanFromVersion identifies Podman from the version payload.
+func detectPodmanFromVersion(versionInfo *dockerVersionResponse) bool {
+	if versionInfo == nil {
+		return false
+	}
+	for _, component := range versionInfo.Components {
+		if strings.HasPrefix(component.Name, "Podman") {
+			return true
+		}
+	}
+	return false
+}
+
+// detectPodmanEngine checks both header and version metadata for Podman.
+func detectPodmanEngine(serverHeader string, versionInfo *dockerVersionResponse) bool {
+	if detectPodmanFromHeader(serverHeader) {
+		return true
+	}
+	return detectPodmanFromVersion(versionInfo)
+}

agent/docker_test.go

@@ -539,59 +539,53 @@ func TestDockerManagerCreation(t *testing.T) {
 
 func TestCheckDockerVersion(t *testing.T) {
 	tests := []struct {
-		name      string
+		name            string
-		responses []struct {
+		statusCode      int
-			statusCode int
+		body            string
-			body       string
+		server          string
-		}
+		expectSuccess   bool
-		expectedGood     bool
+		expectedGood    bool
-		expectedRequests int
+		expectedPodman  bool
+		expectError     bool
+		expectedRequest string
 	}{
 		{
-			name: "200 with good version on first try",
+			name:            "good docker version",
-			responses: []struct {
+			statusCode:      http.StatusOK,
-				statusCode int
+			body:            `{"Version":"25.0.1"}`,
-				body       string
+			expectSuccess:   true,
-			}{
+			expectedGood:    true,
-				{http.StatusOK, `{"Version":"25.0.1"}`},
+			expectedPodman:  false,
-			},
+			expectedRequest: "/version",
-			expectedGood:     true,
-			expectedRequests: 1,
 		},
 		{
-			name: "200 with old version on first try",
+			name:            "old docker version",
-			responses: []struct {
+			statusCode:      http.StatusOK,
-				statusCode int
+			body:            `{"Version":"24.0.7"}`,
-				body       string
+			expectSuccess:   true,
-			}{
+			expectedGood:    false,
-				{http.StatusOK, `{"Version":"24.0.7"}`},
+			expectedPodman:  false,
-			},
+			expectedRequest: "/version",
-			expectedGood:     false,
-			expectedRequests: 1,
 		},
 		{
-			name: "non-200 then 200 with good version",
+			name:            "podman from server header",
-			responses: []struct {
+			statusCode:      http.StatusOK,
-				statusCode int
+			body:            `{"Version":"5.5.0"}`,
-				body       string
+			server:          "Libpod/5.5.0",
-			}{
+			expectSuccess:   true,
-				{http.StatusServiceUnavailable, `"not ready"`},
+			expectedGood:    true,
-				{http.StatusOK, `{"Version":"25.1.0"}`},
+			expectedPodman:  true,
-			},
+			expectedRequest: "/version",
-			expectedGood:     true,
-			expectedRequests: 2,
 		},
 		{
-			name: "non-200 on all retries",
+			name:            "non-200 response",
-			responses: []struct {
+			statusCode:      http.StatusServiceUnavailable,
-				statusCode int
+			body:            `"not ready"`,
-				body       string
+			expectSuccess:   false,
-			}{
+			expectedGood:    false,
-				{http.StatusInternalServerError, `"error"`},
+			expectedPodman:  false,
-				{http.StatusUnauthorized, `"error"`},
+			expectError:     true,
-			},
+			expectedRequest: "/version",
-			expectedGood:     false,
-			expectedRequests: 2,
 		},
 	}
 
@@ -599,13 +593,13 @@ func TestCheckDockerVersion(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			requestCount := 0
 			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-				idx := requestCount
 				requestCount++
-				if idx >= len(tt.responses) {
+				assert.Equal(t, tt.expectedRequest, r.URL.EscapedPath())
-					idx = len(tt.responses) - 1
+				if tt.server != "" {
+					w.Header().Set("Server", tt.server)
 				}
-				w.WriteHeader(tt.responses[idx].statusCode)
+				w.WriteHeader(tt.statusCode)
-				fmt.Fprint(w, tt.responses[idx].body)
+				fmt.Fprint(w, tt.body)
 			}))
 			defer server.Close()
 
@@ -617,17 +611,24 @@ func TestCheckDockerVersion(t *testing.T) {
 						},
 					},
 				},
-				retrySleep: func(time.Duration) {},
 			}
 
-			dm.checkDockerVersion()
+			success, err := dm.checkDockerVersion()
 
+			assert.Equal(t, tt.expectSuccess, success)
+			assert.Equal(t, tt.expectSuccess, dm.dockerVersionChecked)
 			assert.Equal(t, tt.expectedGood, dm.goodDockerVersion)
-			assert.Equal(t, tt.expectedRequests, requestCount)
+			assert.Equal(t, tt.expectedPodman, dm.usingPodman)
+			assert.Equal(t, 1, requestCount)
+			if tt.expectError {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
 		})
 	}
 
-	t.Run("request error on all retries", func(t *testing.T) {
+	t.Run("request error", func(t *testing.T) {
 		requestCount := 0
 		dm := &dockerManager{
 			client: &http.Client{
@@ -638,16 +639,171 @@ func TestCheckDockerVersion(t *testing.T) {
 					},
 				},
 			},
-			retrySleep: func(time.Duration) {},
 		}
 
-		dm.checkDockerVersion()
+		success, err := dm.checkDockerVersion()
 
+		assert.False(t, success)
+		require.Error(t, err)
+		assert.False(t, dm.dockerVersionChecked)
 		assert.False(t, dm.goodDockerVersion)
-		assert.Equal(t, 2, requestCount)
+		assert.False(t, dm.usingPodman)
+		assert.Equal(t, 1, requestCount)
 	})
 }
 
+// newDockerManagerForVersionTest creates a dockerManager wired to a test server.
+func newDockerManagerForVersionTest(server *httptest.Server) *dockerManager {
+	return &dockerManager{
+		client: &http.Client{
+			Transport: &http.Transport{
+				DialContext: func(_ context.Context, network, _ string) (net.Conn, error) {
+					return net.Dial(network, server.Listener.Addr().String())
+				},
+			},
+		},
+		containerStatsMap:   make(map[string]*container.Stats),
+		lastCpuContainer:    make(map[uint16]map[string]uint64),
+		lastCpuSystem:       make(map[uint16]map[string]uint64),
+		lastCpuReadTime:     make(map[uint16]map[string]time.Time),
+		networkSentTrackers: make(map[uint16]*deltatracker.DeltaTracker[string, uint64]),
+		networkRecvTrackers: make(map[uint16]*deltatracker.DeltaTracker[string, uint64]),
+		lastNetworkReadTime: make(map[uint16]map[string]time.Time),
+	}
+}
+
+func TestGetDockerStatsChecksDockerVersionAfterContainerList(t *testing.T) {
+	tests := []struct {
+		name            string
+		containerServer string
+		versionServer   string
+		versionBody     string
+		expectedGood    bool
+		expectedPodman  bool
+	}{
+		{
+			name:           "200 with good version on first try",
+			versionBody:    `{"Version":"25.0.1"}`,
+			expectedGood:   true,
+			expectedPodman: false,
+		},
+		{
+			name:           "200 with old version on first try",
+			versionBody:    `{"Version":"24.0.7"}`,
+			expectedGood:   false,
+			expectedPodman: false,
+		},
+		{
+			name:            "podman detected from server header",
+			containerServer: "Libpod/5.5.0",
+			expectedGood:    true,
+			expectedPodman:  true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			requestCounts := map[string]int{}
+			server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				requestCounts[r.URL.EscapedPath()]++
+				switch r.URL.EscapedPath() {
+				case "/containers/json":
+					if tt.containerServer != "" {
+						w.Header().Set("Server", tt.containerServer)
+					}
+					w.WriteHeader(http.StatusOK)
+					fmt.Fprint(w, `[]`)
+				case "/version":
+					if tt.versionServer != "" {
+						w.Header().Set("Server", tt.versionServer)
+					}
+					w.WriteHeader(http.StatusOK)
+					fmt.Fprint(w, tt.versionBody)
+				default:
+					t.Fatalf("unexpected path: %s", r.URL.EscapedPath())
+				}
+			}))
+			defer server.Close()
+
+			dm := newDockerManagerForVersionTest(server)
+
+			stats, err := dm.getDockerStats(defaultCacheTimeMs)
+			require.NoError(t, err)
+			assert.Empty(t, stats)
+			assert.True(t, dm.dockerVersionChecked)
+			assert.Equal(t, tt.expectedGood, dm.goodDockerVersion)
+			assert.Equal(t, tt.expectedPodman, dm.usingPodman)
+			assert.Equal(t, 1, requestCounts["/containers/json"])
+			if tt.expectedPodman {
+				assert.Equal(t, 0, requestCounts["/version"])
+			} else {
+				assert.Equal(t, 1, requestCounts["/version"])
+			}
+
+			stats, err = dm.getDockerStats(defaultCacheTimeMs)
+			require.NoError(t, err)
+			assert.Empty(t, stats)
+			assert.Equal(t, tt.expectedGood, dm.goodDockerVersion)
+			assert.Equal(t, tt.expectedPodman, dm.usingPodman)
+			assert.Equal(t, 2, requestCounts["/containers/json"])
+			if tt.expectedPodman {
+				assert.Equal(t, 0, requestCounts["/version"])
+			} else {
+				assert.Equal(t, 1, requestCounts["/version"])
+			}
+		})
+	}
+
+}
+
+func TestGetDockerStatsRetriesVersionCheckUntilSuccess(t *testing.T) {
+	requestCounts := map[string]int{}
+	versionStatuses := []int{http.StatusServiceUnavailable, http.StatusOK}
+	versionBodies := []string{`"not ready"`, `{"Version":"25.1.0"}`}
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		requestCounts[r.URL.EscapedPath()]++
+		switch r.URL.EscapedPath() {
+		case "/containers/json":
+			w.WriteHeader(http.StatusOK)
+			fmt.Fprint(w, `[]`)
+		case "/version":
+			idx := requestCounts["/version"] - 1
+			if idx >= len(versionStatuses) {
+				idx = len(versionStatuses) - 1
+			}
+			w.WriteHeader(versionStatuses[idx])
+			fmt.Fprint(w, versionBodies[idx])
+		default:
+			t.Fatalf("unexpected path: %s", r.URL.EscapedPath())
+		}
+	}))
+	defer server.Close()
+
+	dm := newDockerManagerForVersionTest(server)
+
+	stats, err := dm.getDockerStats(defaultCacheTimeMs)
+	require.NoError(t, err)
+	assert.Empty(t, stats)
+	assert.False(t, dm.dockerVersionChecked)
+	assert.False(t, dm.goodDockerVersion)
+	assert.Equal(t, 1, requestCounts["/version"])
+
+	stats, err = dm.getDockerStats(defaultCacheTimeMs)
+	require.NoError(t, err)
+	assert.Empty(t, stats)
+	assert.True(t, dm.dockerVersionChecked)
+	assert.True(t, dm.goodDockerVersion)
+	assert.Equal(t, 2, requestCounts["/containers/json"])
+	assert.Equal(t, 2, requestCounts["/version"])
+
+	stats, err = dm.getDockerStats(defaultCacheTimeMs)
+	require.NoError(t, err)
+	assert.Empty(t, stats)
+	assert.Equal(t, 3, requestCounts["/containers/json"])
+	assert.Equal(t, 2, requestCounts["/version"])
+}
+
 func TestCycleCpuDeltas(t *testing.T) {
 	dm := &dockerManager{
 		lastCpuContainer: map[uint16]map[string]uint64{

agent/server.go

@@ -193,7 +193,7 @@ func (a *Agent) handleSSHRequest(w io.Writer, req *common.HubRequest[cbor.RawMes
 
 // handleLegacyStats serves the legacy one-shot stats payload for older hubs
 func (a *Agent) handleLegacyStats(w io.Writer, hubVersion semver.Version) error {
-	stats := a.gatherStats(common.DataRequestOptions{CacheTimeMs: 60_000})
+	stats := a.gatherStats(common.DataRequestOptions{CacheTimeMs: defaultDataCacheTimeMs})
 	return a.writeToSession(w, stats, hubVersion)
 }
 

agent/system.go

@@ -115,6 +115,26 @@ func (a *Agent) refreshSystemDetails() {
 	}
 }
 
+// attachSystemDetails returns details only for fresh default-interval responses.
+func (a *Agent) attachSystemDetails(data *system.CombinedData, cacheTimeMs uint16, includeRequested bool) *system.CombinedData {
+	if cacheTimeMs != defaultDataCacheTimeMs || (!includeRequested && !a.detailsDirty) {
+		return data
+	}
+
+	// copy data to avoid adding details to the original cached struct
+	response := *data
+	response.Details = &a.systemDetails
+	a.detailsDirty = false
+	return &response
+}
+
+// updateSystemDetails applies a mutation to the static details payload and marks
+// it for inclusion on the next fresh default-interval response.
+func (a *Agent) updateSystemDetails(updateFunc func(details *system.Details)) {
+	updateFunc(&a.systemDetails)
+	a.detailsDirty = true
+}
+
 // Returns current info, stats about the host system
 func (a *Agent) getSystemStats(cacheTimeMs uint16) system.Stats {
 	var systemStats system.Stats

agent/system_test.go

@@ -0,0 +1,61 @@
+package agent
+
+import (
+	"testing"
+
+	"github.com/henrygd/beszel/internal/common"
+	"github.com/henrygd/beszel/internal/entities/system"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGatherStatsDoesNotAttachDetailsToCachedRequests(t *testing.T) {
+	agent := &Agent{
+		cache:         NewSystemDataCache(),
+		systemDetails: system.Details{Hostname: "updated-host", Podman: true},
+		detailsDirty:  true,
+	}
+	cached := &system.CombinedData{
+		Info: system.Info{Hostname: "cached-host"},
+	}
+	agent.cache.Set(cached, defaultDataCacheTimeMs)
+
+	response := agent.gatherStats(common.DataRequestOptions{CacheTimeMs: defaultDataCacheTimeMs})
+
+	assert.Same(t, cached, response)
+	assert.Nil(t, response.Details)
+	assert.True(t, agent.detailsDirty)
+	assert.Equal(t, "cached-host", response.Info.Hostname)
+	assert.Nil(t, cached.Details)
+
+	secondResponse := agent.gatherStats(common.DataRequestOptions{CacheTimeMs: defaultDataCacheTimeMs})
+	assert.Same(t, cached, secondResponse)
+	assert.Nil(t, secondResponse.Details)
+}
+
+func TestUpdateSystemDetailsMarksDetailsDirty(t *testing.T) {
+	agent := &Agent{}
+
+	agent.updateSystemDetails(func(details *system.Details) {
+		details.Hostname = "updated-host"
+		details.Podman = true
+	})
+
+	assert.True(t, agent.detailsDirty)
+	assert.Equal(t, "updated-host", agent.systemDetails.Hostname)
+	assert.True(t, agent.systemDetails.Podman)
+
+	original := &system.CombinedData{}
+	realTimeResponse := agent.attachSystemDetails(original, 1000, true)
+	assert.Same(t, original, realTimeResponse)
+	assert.Nil(t, realTimeResponse.Details)
+	assert.True(t, agent.detailsDirty)
+
+	response := agent.attachSystemDetails(original, defaultDataCacheTimeMs, false)
+	require.NotNil(t, response.Details)
+	assert.NotSame(t, original, response)
+	assert.Equal(t, "updated-host", response.Details.Hostname)
+	assert.True(t, response.Details.Podman)
+	assert.False(t, agent.detailsDirty)
+	assert.Nil(t, original.Details)
+}