[cmd/opampsupervisor]: Write agent config and logs to storage directo…

…ry (#34348)

**Description:*
* Writes the agent's `effective.yaml` and `agent.log` to the storage
directory.

**Link to tracking Issue:** Closes #34341

**Testing:**
* Added an e2e test testing that the supervisor writes the files to the
correct location

.chloggen/fix_supervisor-write-files-to-storage.yaml

@@ -0,0 +1,13 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: cmd/opampsupervisor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Write the generated effective config and agent log files to the user-defined storage directory.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [34341]

cmd/opampsupervisor/e2e_test.go

@@ -1191,6 +1191,34 @@ func TestSupervisorPersistsNewInstanceID(t *testing.T) {
 	require.Equal(t, newID, uuid.UUID(newRecievedAgentID))
 }
 
+func TestSupervisorWritesAgentFilesToStorageDir(t *testing.T) {
+	// Tests that the agent logs and effective.yaml are written under the storage directory.
+	storageDir := t.TempDir()
+
+	server := newOpAMPServer(
+		t,
+		defaultConnectingHandler,
+		server.ConnectionCallbacksStruct{},
+	)
+
+	s := newSupervisor(t, "basic", map[string]string{
+		"url":         server.addr,
+		"storage_dir": storageDir,
+	})
+
+	waitForSupervisorConnection(server.supervisorConnected, true)
+
+	t.Logf("Supervisor connected")
+
+	s.Shutdown()
+
+	t.Logf("Supervisor shutdown")
+
+	// Check config and log files are written in storage dir
+	require.FileExists(t, filepath.Join(storageDir, "agent.log"))
+	require.FileExists(t, filepath.Join(storageDir, "effective.yaml"))
+}
+
 func findRandomPort() (int, error) {
 	l, err := net.Listen("tcp", "localhost:0")
 

cmd/opampsupervisor/supervisor/commander/commander.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"sync/atomic"
 	"syscall"
 	"time"
@@ -23,16 +24,18 @@ import (
 type Commander struct {
 	logger  *zap.Logger
 	cfg     config.Agent
+	logsDir string
 	args    []string
 	cmd     *exec.Cmd
 	doneCh  chan struct{}
 	exitCh  chan struct{}
 	running *atomic.Int64
 }
 
-func NewCommander(logger *zap.Logger, cfg config.Agent, args ...string) (*Commander, error) {
+func NewCommander(logger *zap.Logger, logsDir string, cfg config.Agent, args ...string) (*Commander, error) {
 	return &Commander{
 		logger:  logger,
+		logsDir: logsDir,
 		cfg:     cfg,
 		args:    args,
 		running: &atomic.Int64{},
@@ -69,7 +72,7 @@ func (c *Commander) Start(ctx context.Context) error {
 
 	c.logger.Debug("Starting agent", zap.String("agent", c.cfg.Executable))
 
-	logFilePath := "agent.log"
+	logFilePath := filepath.Join(c.logsDir, "agent.log")
 	logFile, err := os.Create(logFilePath)
 	if err != nil {
 		return fmt.Errorf("cannot create %s: %w", logFilePath, err)

cmd/opampsupervisor/supervisor/supervisor.go

@@ -60,8 +60,8 @@ var (
 )
 
 const (
-	persistentStateFilePath = "persistent_state.yaml"
-	agentConfigFilePath     = "effective.yaml"
+	persistentStateFileName = "persistent_state.yaml"
+	agentConfigFileName     = "effective.yaml"
 )
 
 const maxBufferedCustomMessages = 10
@@ -166,7 +166,7 @@ func NewSupervisor(logger *zap.Logger, configFile string) (*Supervisor, error) {
 	}
 
 	var err error
-	s.persistentState, err = loadOrCreatePersistentState(s.persistentStateFile())
+	s.persistentState, err = loadOrCreatePersistentState(s.persistentStateFilePath())
 	if err != nil {
 		return nil, err
 	}
@@ -197,8 +197,9 @@ func NewSupervisor(logger *zap.Logger, configFile string) (*Supervisor, error) {
 
 	s.commander, err = commander.NewCommander(
 		s.logger,
+		s.config.Storage.Directory,
 		s.config.Agent,
-		"--config", agentConfigFilePath,
+		"--config", s.agentConfigFilePath(),
 	)
 	if err != nil {
 		return nil, err
@@ -278,7 +279,7 @@ func (s *Supervisor) getBootstrapInfo() (err error) {
 		return err
 	}
 
-	err = os.WriteFile(agentConfigFilePath, bootstrapConfig, 0600)
+	err = os.WriteFile(s.agentConfigFilePath(), bootstrapConfig, 0600)
 	if err != nil {
 		return fmt.Errorf("failed to write agent config: %w", err)
 	}
@@ -338,8 +339,9 @@ func (s *Supervisor) getBootstrapInfo() (err error) {
 
 	cmd, err := commander.NewCommander(
 		s.logger,
+		s.config.Storage.Directory,
 		s.config.Agent,
-		"--config", agentConfigFilePath,
+		"--config", s.agentConfigFilePath(),
 	)
 	if err != nil {
 		return err
@@ -801,7 +803,7 @@ func (s *Supervisor) loadAndWriteInitialMergedConfig() error {
 
 	// write the initial merged config to disk
 	cfg := s.mergedConfig.Load().(string)
-	if err := os.WriteFile(agentConfigFilePath, []byte(cfg), 0600); err != nil {
+	if err := os.WriteFile(s.agentConfigFilePath(), []byte(cfg), 0600); err != nil {
 		s.logger.Error("Failed to write agent config.", zap.Error(err))
 	}
 
@@ -1046,7 +1048,7 @@ func (s *Supervisor) healthCheck() {
 }
 
 func (s *Supervisor) runAgentProcess() {
-	if _, err := os.Stat(agentConfigFilePath); err == nil {
+	if _, err := os.Stat(s.agentConfigFilePath()); err == nil {
 		// We have an effective config file saved previously. Use it to start the agent.
 		s.logger.Debug("Effective config found, starting agent initial time")
 		s.startAgent()
@@ -1118,7 +1120,7 @@ func (s *Supervisor) stopAgentApplyConfig() {
 		s.logger.Error("Could not stop agent process", zap.Error(err))
 	}
 
-	if err := os.WriteFile(agentConfigFilePath, []byte(cfg), 0600); err != nil {
+	if err := os.WriteFile(s.agentConfigFilePath(), []byte(cfg), 0600); err != nil {
 		s.logger.Error("Failed to write agent config.", zap.Error(err))
 	}
 }
@@ -1309,8 +1311,12 @@ func (s *Supervisor) processAgentIdentificationMessage(msg *protobufs.AgentIdent
 	return true
 }
 
-func (s *Supervisor) persistentStateFile() string {
-	return filepath.Join(s.config.Storage.Directory, persistentStateFilePath)
+func (s *Supervisor) persistentStateFilePath() string {
+	return filepath.Join(s.config.Storage.Directory, persistentStateFileName)
+}
+
+func (s *Supervisor) agentConfigFilePath() string {
+	return filepath.Join(s.config.Storage.Directory, agentConfigFileName)
 }
 
 func (s *Supervisor) findRandomPort() (int, error) {