Add '-f' flag to logs command

- Support logs '-n' > VC/ESX BrowseLog max

- Add DiagnosticLog helper

- Add doc for logs commands

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### unreleased
 
+* Add DiagnosticLog helper
+
 * Add DatastorePath helper
 
 ### 0.12.0 (2016-12-01)

govc/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### unreleased
 
+* Add '-f' flag to logs command
+
 * Add storage support to vm.migrate
 
 * Add support for file backed serialport devices

govc/USAGE.md

@@ -1604,20 +1604,35 @@ View VPX and ESX logs.
 The '-log' option defaults to "hostd" when connected directly to a host or
 when connected to VirtualCenter and a '-host' option is given.  Otherwise,
 the '-log' option defaults to "vpxd:vpxd.log".  The '-host' option is ignored
-when connected directly to host.
-See 'govc logs.ls' for other '-log' options.
+when connected directly to a host.  See 'govc logs.ls' for other '-log' options.
+
+Examples:
+  govc logs -n 1000 -f
+  govc logs -host esx1
+  govc logs -host esx1 -log vmkernel
 
 Options:
+  -f=false                  Follow log file changes
   -host=                    Host system [GOVC_HOST]
   -log=                     Log file key
-  -n=25                     Output the last N logs
+  -n=25                     Output the last N log lines
 ```
 
 ## logs.download
 
 ```
 Usage: govc logs.download [OPTIONS] [PATH]...
 
+Generate diagnostic bundles.
+
+A diagnostic bundle includes log files and other configuration information.
+
+Use PATH to include a specific set of hosts to include.
+
+Examples:
+  govc logs.download
+  govc logs.download host-a host-b
+
 Options:
   -default=true             Specifies if the bundle should include the default server
 ```
@@ -1627,6 +1642,12 @@ Options:
 ```
 Usage: govc logs.ls [OPTIONS]
 
+List diagnostic log keys.
+
+Examples:
+  govc logs.ls
+  govc logs.ls -host host-a
+
 Options:
   -host=                    Host system [GOVC_HOST]
 ```

govc/emacs/README.md

@@ -119,6 +119,7 @@ during initialization.
 Keybinding     | Description
 ---------------|------------------------------------------------------------
 <kbd>E</kbd>   | Events via govc events -n `govc-max-events`
+<kbd>L</kbd>   | Logs via govc logs -n `govc-max-events`
 <kbd>J</kbd>   | JSON via govc host
 <kbd>N</kbd>   | Netstat via `govc-esxcli-netstat-info` with current host id
 <kbd>c</kbd>   | Connect new session for the current govc mode

govc/emacs/govc.el

@@ -466,7 +466,7 @@ Also fixes the case where user contains an '@'."
     (with-current-buffer (get-buffer current-prefix-arg)
       (setq govc-session-url url))))
 
-(defcustom govc-max-events 50
+(defcustom govc-max-events 100
   "Limit events output to the last N events."
   :type 'integer
   :group 'govc)
@@ -478,6 +478,14 @@ Also fixes the case where user contains an '@'."
    (govc-command "events"
                  (list "-n" govc-max-events (if current-prefix-arg "-f") (govc-selection)))))
 
+(defun govc-logs ()
+  "Logs via govc logs -n `govc-max-events'."
+  (interactive)
+  (govc-shell-command
+   (let ((host (govc-selection)))
+     (govc-command "logs"
+                   (list "-n" govc-max-events (if current-prefix-arg "-f") (if host (list "-host" host)))))))
+
 (defun govc-parse-info (output)
   "Parse govc info command OUTPUT."
   (let* ((entries)
@@ -656,6 +664,7 @@ Also fixes the case where user contains an '@'."
 (defvar govc-host-mode-map
   (let ((map (make-sparse-keymap)))
     (define-key map "E" 'govc-events)
+    (define-key map "L" 'govc-logs)
     (define-key map "J" 'govc-host-json-info)
     (define-key map "N" 'govc-host-esxcli-netstat)
     (define-key map "c" 'govc-mode-new-session)

govc/logs/command.go

@@ -19,8 +19,7 @@ package logs
 import (
 	"context"
 	"flag"
-	"fmt"
-	"math"
+	"time"
 
 	"github.com/vmware/govmomi/govc/cli"
 	"github.com/vmware/govmomi/govc/flags"
@@ -32,6 +31,8 @@ type logs struct {
 
 	Max int32
 	Key string
+
+	follow bool
 }
 
 func init() {
@@ -43,8 +44,9 @@ func (cmd *logs) Register(ctx context.Context, f *flag.FlagSet) {
 	cmd.HostSystemFlag.Register(ctx, f)
 
 	cmd.Max = 25 // default
-	f.Var(flags.NewInt32(&cmd.Max), "n", "Output the last N logs")
+	f.Var(flags.NewInt32(&cmd.Max), "n", "Output the last N log lines")
 	f.StringVar(&cmd.Key, "log", "", "Log file key")
+	f.BoolVar(&cmd.follow, "f", false, "Follow log file changes")
 }
 
 func (cmd *logs) Process(ctx context.Context) error {
@@ -60,8 +62,12 @@ func (cmd *logs) Description() string {
 The '-log' option defaults to "hostd" when connected directly to a host or
 when connected to VirtualCenter and a '-host' option is given.  Otherwise,
 the '-log' option defaults to "vpxd:vpxd.log".  The '-host' option is ignored
-when connected directly to host.
-See 'govc logs.ls' for other '-log' options.`
+when connected directly to a host.  See 'govc logs.ls' for other '-log' options.
+
+Examples:
+  govc logs -n 1000 -f
+  govc logs -host esx1
+  govc logs -host esx1 -log vmkernel`
 }
 
 func (cmd *logs) Run(ctx context.Context, f *flag.FlagSet) error {
@@ -91,20 +97,24 @@ func (cmd *logs) Run(ctx context.Context, f *flag.FlagSet) error {
 		key = defaultKey
 	}
 
-	// get LineEnd without any LineText
-	h, err := m.BrowseLog(ctx, host, key, math.MaxInt32, 0)
-	if err != nil {
-		return err
-	}
+	l := m.Log(ctx, host, key)
 
-	start := h.LineEnd - cmd.Max
-	h, err = m.BrowseLog(ctx, host, key, start, 0)
+	err = l.Seek(ctx, cmd.Max)
 	if err != nil {
 		return err
 	}
 
-	for _, line := range h.LineText {
-		fmt.Println(line)
+	for {
+		_, err = l.Copy(ctx, cmd.Out)
+		if err != nil {
+			return nil
+		}
+
+		if !cmd.follow {
+			break
+		}
+
+		<-time.After(time.Second)
 	}
 
 	return nil

govc/logs/download.go

@@ -58,6 +58,18 @@ func (cmd *download) Usage() string {
 	return "[PATH]..."
 }
 
+func (cmd *download) Description() string {
+	return `Generate diagnostic bundles.
+
+A diagnostic bundle includes log files and other configuration information.
+
+Use PATH to include a specific set of hosts to include.
+
+Examples:
+  govc logs.download
+  govc logs.download host-a host-b`
+}
+
 func (cmd *download) DownloadFile(c *vim25.Client, b string) error {
 	u, err := c.Client.ParseURL(b)
 	if err != nil {

govc/logs/ls.go

@@ -48,6 +48,14 @@ func (cmd *ls) Process(ctx context.Context) error {
 	return nil
 }
 
+func (cmd *ls) Description() string {
+	return `List diagnostic log keys.
+
+Examples:
+  govc logs.ls
+  govc logs.ls -host host-a`
+}
+
 func (cmd *ls) Run(ctx context.Context, f *flag.FlagSet) error {
 	c, err := cmd.Client()
 	if err != nil {

govc/test/logs.bats

@@ -10,7 +10,7 @@ load test_helper
   [ $nlogs -ge 1 ]
 
   # test -n flag
-  run govc logs -n $((nlogs - 1))
+  run govc logs -n $((nlogs - 10))
   assert_success
   [ ${#lines[@]} -le $nlogs ]
 
@@ -20,6 +20,10 @@ load test_helper
   # there should be plenty more than 1 line of vmkernel logs
   [ $nlogs -ge 1 ]
 
+  # test > 1 call to BrowseLog()
+  run govc logs -n 2002
+  assert_success
+
   # -host ignored against ESX
   run govc logs -host enoent
   assert_success

object/diagnostic_log.go

@@ -0,0 +1,76 @@
+/*
+Copyright (c) 2015 VMware, Inc. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package object
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"math"
+)
+
+// DiagnosticLog wraps DiagnosticManager.BrowseLog
+type DiagnosticLog struct {
+	m DiagnosticManager
+
+	Key  string
+	Host *HostSystem
+
+	Start int32
+}
+
+// Seek to log position starting at the last nlines of the log
+func (l *DiagnosticLog) Seek(ctx context.Context, nlines int32) error {
+	h, err := l.m.BrowseLog(ctx, l.Host, l.Key, math.MaxInt32, 0)
+	if err != nil {
+		return err
+	}
+
+	l.Start = h.LineEnd - nlines
+
+	return nil
+}
+
+// Copy log starting from l.Start to the given io.Writer
+// Returns on error or when end of log is reached.
+func (l *DiagnosticLog) Copy(ctx context.Context, w io.Writer) (int, error) {
+	const max = 500 // VC max == 500, ESX max == 1000
+	written := 0
+
+	for {
+		h, err := l.m.BrowseLog(ctx, l.Host, l.Key, l.Start, max)
+		if err != nil {
+			return 0, err
+		}
+
+		for _, line := range h.LineText {
+			n, err := fmt.Fprintln(w, line)
+			written += n
+			if err != nil {
+				return written, err
+			}
+		}
+
+		l.Start += int32(len(h.LineText))
+
+		if l.Start >= h.LineEnd {
+			break
+		}
+	}
+
+	return written, nil
+}

object/diagnostic_manager.go

@@ -36,6 +36,14 @@ func NewDiagnosticManager(c *vim25.Client) *DiagnosticManager {
 	return &m
 }
 
+func (m DiagnosticManager) Log(ctx context.Context, host *HostSystem, key string) *DiagnosticLog {
+	return &DiagnosticLog{
+		m:    m,
+		Key:  key,
+		Host: host,
+	}
+}
+
 func (m DiagnosticManager) BrowseLog(ctx context.Context, host *HostSystem, key string, start, lines int32) (*types.DiagnosticManagerLogHeader, error) {
 	req := types.BrowseDiagnosticLog{
 		This:  m.Reference(),