[v13] Machine ID: Support for JSON log formatting (#30763)

* Support for json log output in `tbot`

* Fix spacing in docs

* fix markdown spacing

docs/pages/reference/cli/tbot.mdx

@@ -35,8 +35,9 @@ Starts the Machine ID client `tbot`, fetching and writing certificates to disk a
 | `--destination-dir`  | Directory to write short-lived machine certificates.                                           |
 | `--certificate-ttl`  | TTL of short-lived machine certificates.                                                       |
 | `--renewal-interval` | Interval at which short-lived certificates are renewed; must be less than the certificate TTL. |
-| `--join-method`      | Method to use to join the cluster. Can be `token` or `iam`.                                    |
+| `--join-method`      | Method to use to join the cluster. Can be `token`, `azure`, `circleci`, `gcp`, `github`, `gitlab` or `iam`. |
 | `--oneshot`          | If set, quit after the first renewal.                                                          |
+| `--log-format`       | Controls the format of output logs. Can be `json` or `text`. Defaults to `text`.               |
 
 ### Examples
 <Tabs>
@@ -85,6 +86,7 @@ configuring either file or POSIX ACL permissions.
 | `--reader-user`     | Enables POSIX ACLs and defines the Linux user that will read short-lived certificates from `--destination-dir`.    |
 | `--init-dir`        | If using a config file and multiple destinations are configured, controls which destination dir to configure.      |
 | `--clean`           | If set, remove unexpected files and directories from the destination.                                              |
+| `--log-format`      | Controls the format of output logs. Can be `json` or `text`. Defaults to `text`.                                   |
 
 ### Examples
 

lib/tbot/config/config.go

@@ -79,12 +79,21 @@ func RemainingArgs(s kingpin.Settings) (target *[]string) {
 	return
 }
 
+const (
+	LogFormatJSON = "json"
+	LogFormatText = "text"
+)
+
 // CLIConf is configuration from the CLI.
 type CLIConf struct {
 	ConfigPath string
 
 	Debug bool
 
+	// LogFormat controls the format of logging. Can be either `json` or `text`.
+	// By default, this is `text`.
+	LogFormat string
+
 	// AuthServer is a Teleport auth server address. It may either point
 	// directly to an auth server, or to a Teleport proxy server in which case
 	// a tunneled auth connection will be established.

tool/tbot/main.go

@@ -61,7 +61,6 @@ Find out more at https://goteleport.com/docs/machine-id/introduction/`
 
 func Run(args []string, stdout io.Writer) error {
 	var cf config.CLIConf
-	utils.InitLogger(utils.LoggingForDaemon, logrus.InfoLevel)
 
 	app := utils.InitCLIParser("tbot", appHelp).Interspersed(false)
 	app.Flag("debug", "Verbose logging to stdout.").Short('d').BoolVar(&cf.Debug)
@@ -87,6 +86,9 @@ func Run(args []string, stdout io.Writer) error {
 	startCmd.Flag("join-method", "Method to use to join the cluster. "+joinMethodList).Default(config.DefaultJoinMethod).EnumVar(&cf.JoinMethod, config.SupportedJoinMethods...)
 	startCmd.Flag("oneshot", "If set, quit after the first renewal.").BoolVar(&cf.Oneshot)
 	startCmd.Flag("diag-addr", "If set and the bot is in debug mode, a diagnostics service will listen on specified address.").StringVar(&cf.DiagAddr)
+	startCmd.Flag("log-format", "Controls the format of output logs. Can be `json` or `text`. Defaults to `text`.").
+		Default(config.LogFormatText).
+		EnumVar(&cf.LogFormat, config.LogFormatJSON, config.LogFormatText)
 
 	initCmd := app.Command("init", "Initialize a certificate destination directory for writes from a separate bot user.")
 	initCmd.Flag("destination-dir", "Directory to write short-lived machine certificates to.").StringVar(&cf.DestinationDir)
@@ -95,6 +97,9 @@ func Run(args []string, stdout io.Writer) error {
 	initCmd.Flag("reader-user", "Enables POSIX ACLs and defines Linux user that will read short-lived certificates from \"--destination-dir\".").StringVar(&cf.ReaderUser)
 	initCmd.Flag("init-dir", "If using a config file and multiple destinations are configured, controls which destination dir to configure.").StringVar(&cf.InitDir)
 	initCmd.Flag("clean", "If set, remove unexpected files and directories from the destination.").BoolVar(&cf.Clean)
+	initCmd.Flag("log-format", "Controls the format of output logs. Can be `json` or `text`. Defaults to `text`.").
+		Default(config.LogFormatText).
+		EnumVar(&cf.LogFormat, config.LogFormatJSON, config.LogFormatText)
 
 	configureCmd := app.Command("configure", "Creates a config file based on flags provided, and writes it to stdout or a file (-c <path>).")
 	configureCmd.Flag("auth-server", "Address of the Teleport Auth Server (On-Prem installs) or Proxy Server (Cloud installs).").Short('a').Envar(authServerEnvVar).StringVar(&cf.AuthServer)
@@ -106,6 +111,9 @@ func Run(args []string, stdout io.Writer) error {
 	configureCmd.Flag("renewal-interval", "Interval at which short-lived certificates are renewed; must be less than the certificate TTL.").DurationVar(&cf.RenewalInterval)
 	configureCmd.Flag("token", "A bot join token, if attempting to onboard a new bot; used on first connect.").Envar(tokenEnvVar).StringVar(&cf.Token)
 	configureCmd.Flag("output", "Path to write the generated configuration file to rather than write to stdout.").Short('o').StringVar(&cf.ConfigureOutput)
+	configureCmd.Flag("log-format", "Controls the format of output logs. Can be `json` or `text`. Defaults to `text`.").
+		Default(config.LogFormatText).
+		EnumVar(&cf.LogFormat, config.LogFormatJSON, config.LogFormatText)
 
 	watchCmd := app.Command("watch", "Watch a destination directory for changes.").Hidden()
 
@@ -147,9 +155,8 @@ func Run(args []string, stdout io.Writer) error {
 		cf.RemainingArgs = *proxyRemaining
 	}
 
-	// While in debug mode, send logs to stdout.
-	if cf.Debug {
-		utils.InitLogger(utils.LoggingForDaemon, logrus.DebugLevel)
+	if err := setupLogger(cf.Debug, cf.LogFormat); err != nil {
+		return trace.Wrap(err, "setting up logger")
 	}
 
 	botConfig, err := config.FromCLIConf(&cf)
@@ -298,3 +305,23 @@ func handleSignals(log logrus.FieldLogger, reload chan struct{}, cancel context.
 		}
 	}
 }
+
+func setupLogger(debug bool, format string) error {
+	level := logrus.InfoLevel
+	if debug {
+		level = logrus.DebugLevel
+	}
+	utils.InitLogger(utils.LoggingForDaemon, level)
+
+	switch format {
+	case config.LogFormatJSON:
+		formatter := &utils.JSONFormatter{}
+		logrus.SetFormatter(formatter)
+	case config.LogFormatText, "":
+	// Nothing to do, this is the default set up by utils.InitLogger
+	default:
+		return trace.BadParameter("unsupported log format %q", format)
+	}
+
+	return nil
+}