add basic systemd service monitoring (#1153)

Co-authored-by: Shelby Tucker <shelby.tucker@gmail.com>

internal/hub/ws/handlers.go

@@ -7,6 +7,7 @@ import (
 	"github.com/fxamacker/cbor/v2"
 	"github.com/henrygd/beszel/internal/common"
 	"github.com/henrygd/beszel/internal/entities/system"
+	"github.com/henrygd/beszel/internal/entities/systemd"
 	"github.com/lxzan/gws"
 	"golang.org/x/crypto/ssh"
 )
@@ -115,6 +116,44 @@ func (ws *WsConn) RequestContainerInfo(ctx context.Context, containerID string)
 ////////////////////////////////////////////////////////////////////////////
 ////////////////////////////////////////////////////////////////////////////
 
+// RequestSystemdInfo requests detailed information about a systemd service via WebSocket.
+func (ws *WsConn) RequestSystemdInfo(ctx context.Context, serviceName string) (systemd.ServiceDetails, error) {
+	if !ws.IsConnected() {
+		return nil, gws.ErrConnClosed
+	}
+
+	req, err := ws.requestManager.SendRequest(ctx, common.GetSystemdInfo, common.SystemdInfoRequest{ServiceName: serviceName})
+	if err != nil {
+		return nil, err
+	}
+
+	var result systemd.ServiceDetails
+	handler := &systemdInfoHandler{result: &result}
+	if err := ws.handleAgentRequest(req, handler); err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+// systemdInfoHandler parses ServiceDetails from AgentResponse
+type systemdInfoHandler struct {
+	BaseHandler
+	result *systemd.ServiceDetails
+}
+
+func (h *systemdInfoHandler) Handle(agentResponse common.AgentResponse) error {
+	if agentResponse.ServiceInfo == nil {
+		return errors.New("no systemd info in response")
+	}
+	*h.result = agentResponse.ServiceInfo
+	return nil
+}
+
+////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////
+
 // RequestSmartData requests SMART data via WebSocket.
 func (ws *WsConn) RequestSmartData(ctx context.Context) (map[string]any, error) {
 	if !ws.IsConnected() {

internal/hub/ws/handlers_test.go

@@ -0,0 +1,75 @@
+//go:build testing
+
+package ws
+
+import (
+	"testing"
+
+	"github.com/henrygd/beszel/internal/common"
+	"github.com/henrygd/beszel/internal/entities/systemd"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSystemdInfoHandlerSuccess(t *testing.T) {
+	handler := &systemdInfoHandler{
+		result: &systemd.ServiceDetails{},
+	}
+
+	// Test successful handling with valid ServiceInfo
+	testDetails := systemd.ServiceDetails{
+		"Id":             "nginx.service",
+		"ActiveState":    "active",
+		"SubState":       "running",
+		"Description":    "A high performance web server",
+		"ExecMainPID":    1234,
+		"MemoryCurrent":  1024000,
+	}
+
+	response := common.AgentResponse{
+		ServiceInfo: testDetails,
+	}
+
+	err := handler.Handle(response)
+	assert.NoError(t, err)
+	assert.Equal(t, testDetails, *handler.result)
+}
+
+func TestSystemdInfoHandlerError(t *testing.T) {
+	handler := &systemdInfoHandler{
+		result: &systemd.ServiceDetails{},
+	}
+
+	// Test error handling when ServiceInfo is nil
+	response := common.AgentResponse{
+		ServiceInfo: nil,
+		Error:       "service not found",
+	}
+
+	err := handler.Handle(response)
+	assert.Error(t, err)
+	assert.Equal(t, "no systemd info in response", err.Error())
+}
+
+func TestSystemdInfoHandlerEmptyResponse(t *testing.T) {
+	handler := &systemdInfoHandler{
+		result: &systemd.ServiceDetails{},
+	}
+
+	// Test with completely empty response
+	response := common.AgentResponse{}
+
+	err := handler.Handle(response)
+	assert.Error(t, err)
+	assert.Equal(t, "no systemd info in response", err.Error())
+}
+
+func TestSystemdInfoHandlerLegacyNotSupported(t *testing.T) {
+	handler := &systemdInfoHandler{
+		result: &systemd.ServiceDetails{},
+	}
+
+	// Test that legacy format is not supported
+	err := handler.HandleLegacy([]byte("some data"))
+	assert.Error(t, err)
+	assert.Equal(t, "legacy format not supported", err.Error())
+}