Nomad Monitor

api/agent.go

@@ -237,6 +237,57 @@ func (a *Agent) Health() (*AgentHealthResponse, error) {
 	return nil, fmt.Errorf("unable to unmarshal response with status %d: %v", resp.StatusCode, err)
 }
 
+// Monitor returns a channel which will receive streaming logs from the agent
+// Providing a non-nil stopCh can be used to close the connection and stop log streaming
+func (a *Agent) Monitor(stopCh <-chan struct{}, q *QueryOptions) (<-chan *StreamFrame, <-chan error) {
+	errCh := make(chan error, 1)
+	r, err := a.client.newRequest("GET", "/v1/agent/monitor")
+	if err != nil {
+		errCh <- err
+		return nil, errCh
+	}
+
+	r.setQueryOptions(q)
+	_, resp, err := requireOK(a.client.doRequest(r))
+	if err != nil {
+		errCh <- err
+		return nil, errCh
+	}
+
+	frames := make(chan *StreamFrame, 10)
+	go func() {
+		defer resp.Body.Close()
+
+		dec := json.NewDecoder(resp.Body)
+
+		for {
+			select {
+			case <-stopCh:
+				close(frames)
+				return
+			default:
+			}
+
+			// Decode the next frame
+			var frame StreamFrame
+			if err := dec.Decode(&frame); err != nil {
+				close(frames)
+				errCh <- err
+				return
+			}
+
+			// Discard heartbeat frame
+			if frame.IsHeartbeat() {
+				continue
+			}
+
+			frames <- &frame
+		}
+	}()
+
+	return frames, errCh
+}
+
 // joinResponse is used to decode the response we get while
 // sending a member join request.
 type joinResponse struct {

api/agent_test.go

@@ -1,9 +1,15 @@
 package api
 
 import (
+	"fmt"
 	"reflect"
 	"sort"
+	"strings"
 	"testing"
+	"time"
+
+	"github.com/kr/pretty"
+	"github.com/stretchr/testify/require"
 
 	"github.com/hashicorp/nomad/api/internal/testutil"
 	"github.com/stretchr/testify/assert"
@@ -257,3 +263,116 @@ func TestAgent_Health(t *testing.T) {
 	assert.Nil(err)
 	assert.True(health.Server.Ok)
 }
+
+// TestAgent_MonitorWithNode tests the Monitor endpoint
+// passing in a log level and node ie, which tests monitor
+// functionality for a specific client node
+func TestAgent_MonitorWithNode(t *testing.T) {
+	t.Parallel()
+	rpcPort := 0
+	c, s := makeClient(t, nil, func(c *testutil.TestServerConfig) {
+		rpcPort = c.Ports.RPC
+		c.Client = &testutil.ClientConfig{
+			Enabled: true,
+		}
+	})
+	defer s.Stop()
+
+	require.NoError(t, c.Agent().SetServers([]string{fmt.Sprintf("127.0.0.1:%d", rpcPort)}))
+
+	agent := c.Agent()
+
+	index := uint64(0)
+	var node *NodeListStub
+	// grab a node
+	testutil.WaitForResult(func() (bool, error) {
+		nodes, qm, err := c.Nodes().List(&QueryOptions{WaitIndex: index})
+		if err != nil {
+			return false, err
+		}
+		index = qm.LastIndex
+		if len(nodes) != 1 {
+			return false, fmt.Errorf("expected 1 node but found: %s", pretty.Sprint(nodes))
+		}
+		if nodes[0].Status != "ready" {
+			return false, fmt.Errorf("node not ready: %s", nodes[0].Status)
+		}
+		node = nodes[0]
+		return true, nil
+	}, func(err error) {
+		t.Fatalf("err: %v", err)
+	})
+
+	doneCh := make(chan struct{})
+	q := &QueryOptions{
+		Params: map[string]string{
+			"log_level": "debug",
+			"node_id":   node.ID,
+		},
+	}
+
+	frames, errCh := agent.Monitor(doneCh, q)
+	defer close(doneCh)
+
+	// make a request to generate some logs
+	_, err := agent.NodeName()
+	require.NoError(t, err)
+
+	// Wait for a log message
+OUTER:
+	for {
+		select {
+		case f := <-frames:
+			if strings.Contains(string(f.Data), "[DEBUG]") {
+				break OUTER
+			}
+		case err := <-errCh:
+			t.Errorf("Error: %v", err)
+		case <-time.After(2 * time.Second):
+			require.Fail(t, "failed to get a DEBUG log message")
+		}
+	}
+}
+
+// TestAgent_Monitor tests the Monitor endpoint
+// passing in only a log level, which tests the servers
+// monitor functionality
+func TestAgent_Monitor(t *testing.T) {
+	t.Parallel()
+	c, s := makeClient(t, nil, nil)
+	defer s.Stop()
+
+	agent := c.Agent()
+
+	q := &QueryOptions{
+		Params: map[string]string{
+			"log_level": "debug",
+		},
+	}
+
+	doneCh := make(chan struct{})
+	frames, errCh := agent.Monitor(doneCh, q)
+	defer close(doneCh)
+
+	// make a request to generate some logs
+	_, err := agent.Region()
+	require.NoError(t, err)
+
+	// Wait for a log message
+OUTER:
+	for {
+		select {
+		case log := <-frames:
+			if log == nil {
+				continue
+			}
+			if strings.Contains(string(log.Data), "[DEBUG]") {
+				break OUTER
+			}
+		case err := <-errCh:
+			t.Fatalf("error: %v", err)
+		case <-time.After(2 * time.Second):
+			require.Fail(t, "failed to get a DEBUG log message")
+		}
+	}
+}

client/agent_endpoint.go

@@ -0,0 +1,163 @@
+package client
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"io"
+	"time"
+
+	"github.com/hashicorp/nomad/command/agent/monitor"
+	"github.com/hashicorp/nomad/helper"
+	"github.com/hashicorp/nomad/nomad/structs"
+	"github.com/ugorji/go/codec"
+
+	metrics "github.com/armon/go-metrics"
+	log "github.com/hashicorp/go-hclog"
+	sframer "github.com/hashicorp/nomad/client/lib/streamframer"
+	cstructs "github.com/hashicorp/nomad/client/structs"
+)
+
+type Agent struct {
+	c *Client
+}
+
+func NewAgentEndpoint(c *Client) *Agent {
+	m := &Agent{c: c}
+	m.c.streamingRpcs.Register("Agent.Monitor", m.monitor)
+	return m
+}
+
+func (m *Agent) monitor(conn io.ReadWriteCloser) {
+	defer metrics.MeasureSince([]string{"client", "agent", "monitor"}, time.Now())
+	defer conn.Close()
+
+	// Decode arguments
+	var args cstructs.MonitorRequest
+	decoder := codec.NewDecoder(conn, structs.MsgpackHandle)
+	encoder := codec.NewEncoder(conn, structs.MsgpackHandle)
+
+	if err := decoder.Decode(&args); err != nil {
+		handleStreamResultError(err, helper.Int64ToPtr(500), encoder)
+		return
+	}
+
+	// Check acl
+	if aclObj, err := m.c.ResolveToken(args.AuthToken); err != nil {
+		handleStreamResultError(err, helper.Int64ToPtr(403), encoder)
+		return
+	} else if aclObj != nil && !aclObj.AllowAgentRead() {
+		handleStreamResultError(structs.ErrPermissionDenied, helper.Int64ToPtr(403), encoder)
+		return
+	}
+
+	logLevel := log.LevelFromString(args.LogLevel)
+	if args.LogLevel == "" {
+		logLevel = log.LevelFromString("INFO")
+	}
+
+	if logLevel == log.NoLevel {
+		handleStreamResultError(errors.New("Unknown log level"), helper.Int64ToPtr(400), encoder)
+		return
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	monitor := monitor.New(512, m.c.logger, &log.LoggerOptions{
+		JSONFormat: args.LogJSON,
+		Level:      logLevel,
+	})
+
+	frames := make(chan *sframer.StreamFrame, streamFramesBuffer)
+	errCh := make(chan error)
+	var buf bytes.Buffer
+	frameCodec := codec.NewEncoder(&buf, structs.JsonHandle)
+
+	framer := sframer.NewStreamFramer(frames, 1*time.Second, 200*time.Millisecond, 1024)
+	framer.Run()
+	defer framer.Destroy()
+
+	// goroutine to detect remote side closing
+	go func() {
+		if _, err := conn.Read(nil); err != nil {
+			// One end of the pipe explicitly closed, exit
+			cancel()
+			return
+		}
+		select {
+		case <-ctx.Done():
+			return
+		}
+	}()
+
+	logCh := monitor.Start()
+	defer monitor.Stop()
+	initialOffset := int64(0)
+
+	// receive logs and build frames
+	go func() {
+		defer framer.Destroy()
+	LOOP:
+		for {
+			select {
+			case log := <-logCh:
+				if err := framer.Send("", "log", log, initialOffset); err != nil {
+					select {
+					case errCh <- err:
+					case <-ctx.Done():
+					}
+					break LOOP
+				}
+			case <-ctx.Done():
+				break LOOP
+			}
+		}
+	}()
+
+	var streamErr error
+OUTER:
+	for {
+		select {
+		case frame, ok := <-frames:
+			if !ok {
+				// frame may have been closed when an error
+				// occurred. Check once more for an error.
+				select {
+				case streamErr = <-errCh:
+					// There was a pending error!
+				default:
+					// No error, continue on
+				}
+
+				break OUTER
+			}
+
+			var resp cstructs.StreamErrWrapper
+			if args.PlainText {
+				resp.Payload = frame.Data
+			} else {
+				if err := frameCodec.Encode(frame); err != nil {
+					streamErr = err
+					break OUTER
+				}
+
+				resp.Payload = buf.Bytes()
+				buf.Reset()
+			}
+
+			if err := encoder.Encode(resp); err != nil {
+				streamErr = err
+				break OUTER
+			}
+			encoder.Reset(conn)
+		case <-ctx.Done():
+			break OUTER
+		}
+	}
+
+	if streamErr != nil {
+		handleStreamResultError(streamErr, helper.Int64ToPtr(500), encoder)
+		return
+	}
+}