package command import ( "fmt" "strings" "sync" "github.com/hashicorp/consul/command/base" ) // MonitorCommand is a Command implementation that queries a running // Consul agent what members are part of the cluster currently. type MonitorCommand struct { base.Command ShutdownCh <-chan struct{} lock sync.Mutex quitting bool } func (c *MonitorCommand) Help() string { helpText := ` Usage: consul monitor [options] Shows recent log messages of a Consul agent, and attaches to the agent, outputting log messages as they occur in real time. The monitor lets you listen for log levels that may be filtered out of the Consul agent. For example your agent may only be logging at INFO level, but with the monitor you can see the DEBUG level logs. ` + c.Command.Help() return strings.TrimSpace(helpText) } func (c *MonitorCommand) Run(args []string) int { var logLevel string f := c.Command.NewFlagSet(c) f.StringVar(&logLevel, "log-level", "INFO", "Log level of the agent.") if err := c.Command.Parse(args); err != nil { return 1 } client, err := c.Command.HTTPClient() if err != nil { c.Ui.Error(fmt.Sprintf("Error connecting to Consul agent: %s", err)) return 1 } eventDoneCh := make(chan struct{}) logCh, err := client.Agent().Monitor(logLevel, eventDoneCh, nil) if err != nil { c.Ui.Error(fmt.Sprintf("Error starting monitor: %s", err)) return 1 } go func() { defer close(eventDoneCh) OUTER: for { select { case log := <-logCh: if log == "" { break OUTER } c.Ui.Info(log) } } c.lock.Lock() defer c.lock.Unlock() if !c.quitting { c.Ui.Info("") c.Ui.Output("Remote side ended the monitor! This usually means that the\n" + "remote side has exited or crashed.") } }() select { case <-eventDoneCh: return 1 case <-c.ShutdownCh: c.lock.Lock() c.quitting = true c.lock.Unlock() } return 0 } func (c *MonitorCommand) Synopsis() string { return "Stream logs from a Consul agent" }