agent/structs: String format for Intention, used for logging

agent/agent_endpoint.go

@@ -921,7 +921,7 @@ func (s *HTTPServer) AgentConnectAuthorize(resp http.ResponseWriter, req *http.R
 	if !ok {
 		return &connectAuthorizeResp{
 			Authorized: false,
-			Reason:     fmt.Sprintf("Client ID must be a valid SPIFFE service URI"),
+			Reason:     "Client ID must be a valid SPIFFE service URI",
 		}, nil
 	}
 
@@ -951,7 +951,7 @@ func (s *HTTPServer) AgentConnectAuthorize(resp http.ResponseWriter, req *http.R
 		if auth, ok := uriService.Authorize(ixn); ok {
 			return &connectAuthorizeResp{
 				Authorized: auth,
-				Reason:     fmt.Sprintf("Matched intention %s", ixn.ID),
+				Reason:     fmt.Sprintf("Matched intention: %s", ixn.String()),
 			}, nil
 		}
 	}

agent/structs/intention.go

@@ -164,6 +164,15 @@ func (x *Intention) GetACLPrefix() (string, bool) {
 	return x.DestinationName, x.DestinationName != ""
 }
 
+// String returns a human-friendly string for this intention.
+func (x *Intention) String() string {
+	return fmt.Sprintf("%s %s/%s => %s/%s (ID: %s",
+		strings.ToUpper(string(x.Action)),
+		x.SourceNS, x.SourceName,
+		x.DestinationNS, x.DestinationName,
+		x.ID)
+}
+
 // IntentionAction is the action that the intention represents. This
 // can be "allow" or "deny" to whitelist or blacklist intentions.
 type IntentionAction string