AgentIdentification protobuf and callback

Implements OpAMP Spec change open-telemetry/opamp-spec#63

client/callbacks.go

@@ -39,6 +39,7 @@ type CallbacksStruct struct {
 
 	OnAddonsAvailableFunc       func(ctx context.Context, addons *protobufs.AddonsAvailable, syncer types.AddonSyncer) error
 	OnAgentPackageAvailableFunc func(addons *protobufs.AgentPackageAvailable, syncer types.AgentPackageSyncer) error
+	OnAgentIdentificationFunc   func(ctx context.Context, agentId *protobufs.AgentIdentification) error
 }
 
 var _ types.Callbacks = (*CallbacksStruct)(nil)
@@ -124,3 +125,13 @@ func (c CallbacksStruct) OnAgentPackageAvailable(
 	}
 	return nil
 }
+
+func (c CallbacksStruct) OnAgentIdentification(
+	ctx context.Context,
+	agentId *protobufs.AgentIdentification,
+) error {
+	if c.OnAgentIdentificationFunc != nil {
+		return c.OnAgentIdentificationFunc(ctx, agentId)
+	}
+	return nil
+}

client/internal/receiver.go

@@ -65,6 +65,7 @@ func (r *Receiver) processReceivedMessage(ctx context.Context, msg *protobufs.Se
 
 		r.rcvConnectionSettings(ctx, msg.ConnectionSettings)
 		r.rcvAddonsAvailable(msg.AddonsAvailable)
+		r.rcvAgentIdentification(ctx, msg.AgentIdentification)
 
 		if reportStatus {
 			r.sender.ScheduleSend()
@@ -168,3 +169,14 @@ func (r *Receiver) processErrorResponse(body *protobufs.ServerErrorResponse) {
 func (r *Receiver) rcvAddonsAvailable(addons *protobufs.AddonsAvailable) {
 	// TODO: implement this.
 }
+
+func (r *Receiver) rcvAgentIdentification(ctx context.Context, agentId *protobufs.AgentIdentification) {
+	if agentId == nil {
+		return
+	}
+
+	err := r.callbacks.OnAgentIdentification(ctx, agentId)
+	if err != nil {
+		// TODO: minimally log the error
+	}
+}

client/types/callbacks.go

@@ -129,6 +129,10 @@ type Callbacks interface {
 	// syncer can be used to initiate syncing the package from the server.
 	OnAgentPackageAvailable(addons *protobufs.AgentPackageAvailable, syncer AgentPackageSyncer) error
 
+	// OnAgentIdentification is called when the server requests changing identification of the agent.
+	// Agent should be updated with new id and use it for all further communication
+	OnAgentIdentification(ctx context.Context, agentId *protobufs.AgentIdentification) error
+
 	// For all methods that accept a context parameter the caller may cancel the
 	// context if processing takes too long. In that case the method should return
 	// as soon as possible with an error.

internal/proto/opamp.proto

@@ -47,6 +47,17 @@ message AgentToServer {
     // AgentDisconnect MUST be set in the last AgentToServer message sent from the
     // agent to the server.
     AgentDisconnect agent_disconnect = 5;
+
+    enum AgentToServerFlags {
+        FlagsUnspecified = 0;
+        // AgentToServerFlags is a bit mask. Values below define individual bits.
+
+        // The agent requests server go generate a new instance_uid, which will
+        // be sent back in ServerToAgent message
+        RequestInstanceUid     = 0x00000001;
+    }
+    // Bit flags as defined by AgentToServerFlags bit masks.
+    AgentToServerFlags flags = 6;
 }
 
 // AgentDisconnect is the last message sent from the agent to the server. The server
@@ -111,6 +122,10 @@ message ServerToAgent {
     // be omitted in subsequent ServerToAgent messages by setting it to
     // UnspecifiedServerCapability value.
     ServerCapabilities capabilities = 8;
+
+    // Properties related to identification of the agent, which can be overridden
+    // by the server if needed.
+    AgentIdentification agent_identification = 9;
 }
 
 enum ServerCapabilities {
@@ -663,6 +678,14 @@ message AgentInstallStatus {
     string error_message = 4;
 }
 
+// Properties related to identification of the agent, which can be overridden
+// by the server if needed
+message AgentIdentification {
+    // When new_instance_uid is set, Agent MUST update instance_uid
+    // to the value provided and use it for all further communication.
+    string new_instance_uid = 1;
+}
+
 /////////////////////////////////////////////////////////////////////////////////////
 // Config messages
 /////////////////////////////////////////////////////////////////////////////////////