[cmd/opampsupervisor]: Allow configuring agent description (#32819)

**Description:** <Describe what has changed.>
* Add options to the configuration that allows configuring the agent
description

**Link to tracking Issue:** Closes #32824

**Testing:** e2e test, unit tests for validation

**Documentation:**
* Updated spec with configuration parameters

---------

Co-authored-by: Tigran Najaryan <[email protected]>

.chloggen/feat_supervisor-agent-description.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: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: opampsupervisor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Adds the ability to configure the agent description
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32824]

cmd/opampsupervisor/e2e_test.go

@@ -416,6 +416,97 @@ func TestSupervisorBootstrapsCollector(t *testing.T) {
 	}, 5*time.Second, 250*time.Millisecond)
 }
 
+func TestSupervisorAgentDescriptionConfigApplies(t *testing.T) {
+	// Load the Supervisor config so we can get the location of
+	// the Collector that will be run.
+	var cfg config.Supervisor
+	cfgFile := getSupervisorConfig(t, "agent_description", map[string]string{})
+	k := koanf.New("::")
+	err := k.Load(file.Provider(cfgFile.Name()), yaml.Parser())
+	require.NoError(t, err)
+	err = k.UnmarshalWithConf("", &cfg, koanf.UnmarshalConf{
+		Tag: "mapstructure",
+	})
+	require.NoError(t, err)
+
+	host, err := os.Hostname()
+	require.NoError(t, err)
+
+	// Get the binary name and version from the Collector binary
+	// using the `components` command that prints a YAML-encoded
+	// map of information about the Collector build. Some of this
+	// information will be used as defaults for the telemetry
+	// attributes.
+	agentPath := cfg.Agent.Executable
+	componentsInfo, err := exec.Command(agentPath, "components").Output()
+	require.NoError(t, err)
+	k = koanf.New("::")
+	err = k.Load(rawbytes.Provider(componentsInfo), yaml.Parser())
+	require.NoError(t, err)
+	buildinfo := k.StringMap("buildinfo")
+	command := buildinfo["command"]
+	version := buildinfo["version"]
+
+	agentDescMessageChan := make(chan *protobufs.AgentToServer, 1)
+
+	server := newOpAMPServer(
+		t,
+		defaultConnectingHandler,
+		server.ConnectionCallbacksStruct{
+			OnMessageFunc: func(_ context.Context, _ types.Connection, message *protobufs.AgentToServer) *protobufs.ServerToAgent {
+				if message.AgentDescription != nil {
+					select {
+					case agentDescMessageChan <- message:
+					default:
+					}
+				}
+
+				return &protobufs.ServerToAgent{}
+			},
+		})
+
+	s := newSupervisor(t, "agent_description", map[string]string{"url": server.addr})
+	defer s.Shutdown()
+
+	waitForSupervisorConnection(server.supervisorConnected, true)
+	var ad *protobufs.AgentToServer
+	select {
+	case ad = <-agentDescMessageChan:
+	case <-time.After(5 * time.Second):
+		t.Fatal("Failed to get agent description after 5 seconds")
+	}
+
+	expectedDescription := &protobufs.AgentDescription{
+		IdentifyingAttributes: []*protobufs.KeyValue{
+			stringKeyValue("client.id", "my-client-id"),
+			stringKeyValue(semconv.AttributeServiceInstanceID, ad.InstanceUid),
+			stringKeyValue(semconv.AttributeServiceName, command),
+			stringKeyValue(semconv.AttributeServiceVersion, version),
+		},
+		NonIdentifyingAttributes: []*protobufs.KeyValue{
+			stringKeyValue("env", "prod"),
+			stringKeyValue(semconv.AttributeHostArch, runtime.GOARCH),
+			stringKeyValue(semconv.AttributeHostName, host),
+			stringKeyValue(semconv.AttributeOSType, runtime.GOOS),
+		},
+	}
+
+	require.Equal(t, expectedDescription, ad.AgentDescription)
+
+	time.Sleep(250 * time.Millisecond)
+}
+
+func stringKeyValue(key, val string) *protobufs.KeyValue {
+	return &protobufs.KeyValue{
+		Key: key,
+		Value: &protobufs.AnyValue{
+			Value: &protobufs.AnyValue_StringValue{
+				StringValue: val,
+			},
+		},
+	}
+}
+
 // Creates a Collector config that reads and writes logs to files and provides
 // file descriptors for I/O operations to those files. The files are placed
 // in a unique temp directory that is cleaned up after the test's completion.

cmd/opampsupervisor/specification/README.md

@@ -119,7 +119,7 @@ storage:
   # and %ProgramData%/Otelcol/Supervisor on Windows.
   directory: /path/to/dir
 
-collector:
+agent:
   # Path to Collector executable. Required.
   executable: /opt/otelcol/bin/otelcol
 
@@ -144,6 +144,17 @@ collector:
       deny: \[/var/log/secret_logs\]
     write:
       allow: \[/var/otelcol\]
+
+  # Optional key-value pairs to add to either the identifying attributes or
+  # non-identifying attributes of the agent description sent to the OpAMP server.
+  # Values here override the values in the agent description retrieved from the collector's
+  # OpAMP extension (self-reported by the Collector).
+  description:
+    identifying_attributes:
+      client.id: "01HWWSK84BMT7J45663MBJMTPJ"
+    non_identifying_attributes:
+      custom.attribute: "custom-value"
+
 ```
 
 ### Executing Collector

cmd/opampsupervisor/supervisor/config/config.go

@@ -40,5 +40,11 @@ type OpAMPServer struct {
 }
 
 type Agent struct {
-	Executable string
+	Executable  string
+	Description AgentDescription `mapstructure:"description"`
+}
+
+type AgentDescription struct {
+	IdentifyingAttributes    map[string]string `mapstructure:"identifying_attributes"`
+	NonIdentifyingAttributes map[string]string `mapstructure:"non_identifying_attributes"`
 }

cmd/opampsupervisor/supervisor/supervisor.go

@@ -256,7 +256,7 @@ func (s *Supervisor) getBootstrapInfo() (err error) {
 		onMessageFunc: func(_ serverTypes.Connection, message *protobufs.AgentToServer) {
 			if message.AgentDescription != nil {
 				instanceIDSeen := false
-				s.agentDescription = message.AgentDescription
+				s.setAgentDescription(message.AgentDescription)
 				identAttr := s.agentDescription.IdentifyingAttributes
 
 				for _, attr := range identAttr {
@@ -431,6 +431,51 @@ func (s *Supervisor) startOpAMP() error {
 	return nil
 }
 
+// setAgentDescription sets the agent description, merging in any user-specified attributes from the supervisor configuration.
+func (s *Supervisor) setAgentDescription(ad *protobufs.AgentDescription) {
+	ad.IdentifyingAttributes = applyKeyValueOverrides(s.config.Agent.Description.IdentifyingAttributes, ad.IdentifyingAttributes)
+	ad.NonIdentifyingAttributes = applyKeyValueOverrides(s.config.Agent.Description.NonIdentifyingAttributes, ad.NonIdentifyingAttributes)
+	s.agentDescription = ad
+}
+
+// applyKeyValueOverrides merges the overrides map into the array of key value pairs.
+// If a key from overrides already exists in the array of key value pairs, it is overwritten by the value from the overrides map.
+// An array of KeyValue pair is returned, with each key value pair having a distinct key.
+func applyKeyValueOverrides(overrides map[string]string, orig []*protobufs.KeyValue) []*protobufs.KeyValue {
+	kvMap := make(map[string]*protobufs.KeyValue, len(orig)+len(overrides))
+
+	for _, kv := range orig {
+		kvMap[kv.Key] = kv
+	}
+
+	for k, v := range overrides {
+		kvMap[k] = &protobufs.KeyValue{
+			Key: k,
+			Value: &protobufs.AnyValue{
+				Value: &protobufs.AnyValue_StringValue{
+					StringValue: v,
+				},
+			},
+		}
+	}
+
+	// Sort keys for stable output, makes it easier to test.
+	keys := make([]string, 0, len(kvMap))
+	for k := range kvMap {
+		keys = append(keys, k)
+	}
+
+	sort.Strings(keys)
+
+	kvOut := make([]*protobufs.KeyValue, 0, len(kvMap))
+	for _, k := range keys {
+		v := kvMap[k]
+		kvOut = append(kvOut, v)
+	}
+
+	return kvOut
+}
+
 func (s *Supervisor) stopOpAMP() error {
 	s.logger.Debug("Stopping OpAMP client...")
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)

cmd/opampsupervisor/testdata/supervisor/supervisor_agent_description.yaml

@@ -0,0 +1,20 @@
+server:
+  endpoint: ws://{{.url}}/v1/opamp
+  tls:
+    insecure: true
+
+capabilities:
+  reports_effective_config: true
+  reports_own_metrics: true
+  reports_health: true
+  accepts_remote_config: true
+  reports_remote_config: true
+  accepts_restart_command: true
+
+agent:
+  executable: ../../bin/otelcontribcol_{{.goos}}_{{.goarch}}{{.extension}}
+  description:
+    identifying_attributes:
+      client.id: "my-client-id"
+    non_identifying_attributes:
+      env: "prod"