Update docs for metrics endpoint

agent/agent.go

@@ -2248,5 +2248,8 @@ func (a *Agent) ReloadConfig(newCfg *Config) error {
 		return fmt.Errorf("Failed reloading watches: %v", err)
 	}
 
+	// Update filtered metrics
+	metrics.UpdateFilter(newCfg.Telemetry.AllowedPrefixes, newCfg.Telemetry.BlockedPrefixes)
+
 	return nil
 }

agent/config.go

@@ -1483,7 +1483,7 @@ func DecodeConfig(r io.Reader) (*Config, error) {
 		case '-':
 			result.Telemetry.BlockedPrefixes = append(result.Telemetry.BlockedPrefixes, rule[1:])
 		default:
-			return nil, fmt.Errorf("Filter rule must begin with either '+' or '-': %s", rule)
+			return nil, fmt.Errorf("Filter rule must begin with either '+' or '-': %q", rule)
 		}
 	}
 

agent/http.go

@@ -98,7 +98,7 @@ func (s *HTTPServer) handler(enableDebug bool) http.Handler {
 	handleFuncMetrics("/v1/agent/maintenance", s.wrap(s.AgentNodeMaintenance))
 	handleFuncMetrics("/v1/agent/reload", s.wrap(s.AgentReload))
 	handleFuncMetrics("/v1/agent/monitor", s.wrap(s.AgentMonitor))
-	handleFuncMetrics("/v1/agent/metrics", s.wrap(s.agent.MemSink.DisplayMetrics))
+	handleFuncMetrics("/v1/agent/metrics", s.wrap(s.requireAgentRead(s.agent.MemSink.DisplayMetrics)))
 	handleFuncMetrics("/v1/agent/services", s.wrap(s.AgentServices))
 	handleFuncMetrics("/v1/agent/checks", s.wrap(s.AgentChecks))
 	handleFuncMetrics("/v1/agent/members", s.wrap(s.AgentMembers))
@@ -264,6 +264,26 @@ func (s *HTTPServer) wrap(handler func(resp http.ResponseWriter, req *http.Reque
 	}
 }
 
+type handlerFunc func(resp http.ResponseWriter, req *http.Request) (interface{}, error)
+
+// requireAgentRead wraps the given function, requiring a token with agent read permissions
+func (s *HTTPServer) requireAgentRead(handler handlerFunc) handlerFunc {
+	return func(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+		// Fetch the ACL token, if any, and enforce agent policy.
+		var token string
+		s.parseToken(req, &token)
+		acl, err := s.agent.resolveToken(token)
+		if err != nil {
+			return nil, err
+		}
+		if acl != nil && !acl.AgentRead(s.agent.config.NodeName) {
+			return nil, errPermissionDenied
+		}
+
+		return handler(resp, req)
+	}
+}
+
 // marshalJSON marshals the object into JSON, respecting the user's pretty-ness
 // configuration.
 func (s *HTTPServer) marshalJSON(req *http.Request, obj interface{}) ([]byte, error) {

website/source/api/agent.html.md

@@ -355,6 +355,21 @@ $ curl \
 }
 ```
 
+- `Timestamp` is the timestamp of the interval for the displayed metrics. Metrics are
+aggregated on a ten second interval, so this value (along with the displayed metrics)
+will change every ten seconds.
+
+- `Gauges` is a list of gauges which store one value that is updated as time goes on,
+such as the amount of memory allocated.
+
+- `Points` is a list of point metrics, which each store a series of points under a given name.
+
+- `Counters` is a list of counters, which store info about a metric that is incremented
+over time such as the number of requests to an HTTP endpoint.
+
+- `Samples` is a list of samples, which store info about the amount of time spent on an
+operation, such as the time taken to serve a request to a specific http endpoint.
+
 ## Stream Logs
 
 This endpoint streams logs from the local agent until the connection is closed.