package command import ( "bytes" "encoding/json" "fmt" "os" "os/exec" "strconv" "strings" "github.com/hashicorp/consul/agent" "github.com/hashicorp/consul/watch" ) // WatchCommand is a Command implementation that is used to setup // a "watch" which uses a sub-process type WatchCommand struct { BaseCommand ShutdownCh <-chan struct{} // flags watchType string key string prefix string service string tag string passingOnly string state string name string shell bool } func (c *WatchCommand) initFlags() { c.InitFlagSet() c.FlagSet.StringVar(&c.watchType, "type", "", "Specifies the watch type. One of key, keyprefix, services, nodes, "+ "service, checks, or event.") c.FlagSet.StringVar(&c.key, "key", "", "Specifies the key to watch. Only for 'key' type.") c.FlagSet.StringVar(&c.prefix, "prefix", "", "Specifies the key prefix to watch. Only for 'keyprefix' type.") c.FlagSet.StringVar(&c.service, "service", "", "Specifies the service to watch. Required for 'service' type, "+ "optional for 'checks' type.") c.FlagSet.StringVar(&c.tag, "tag", "", "Specifies the service tag to filter on. Optional for 'service' type.") c.FlagSet.StringVar(&c.passingOnly, "passingonly", "", "Specifies if only hosts passing all checks are displayed. "+ "Optional for 'service' type, must be one of `[true|false]`. Defaults false.") c.FlagSet.BoolVar(&c.shell, "shell", true, "Use a shell to run the command (can set a custom shell via the SHELL "+ "environment variable).") c.FlagSet.StringVar(&c.state, "state", "", "Specifies the states to watch. Optional for 'checks' type.") c.FlagSet.StringVar(&c.name, "name", "", "Specifies an event name to watch. Only for 'event' type.") } func (c *WatchCommand) Help() string { c.initFlags() return c.HelpCommand(` Usage: consul watch [options] [child...] Watches for changes in a given data view from Consul. If a child process is specified, it will be invoked with the latest results on changes. Otherwise, the latest values are dumped to stdout and the watch terminates. Providing the watch type is required, and other parameters may be required or supported depending on the watch type. `) } func (c *WatchCommand) Run(args []string) int { c.initFlags() if err := c.FlagSet.Parse(args); err != nil { return 1 } // Check for a type if c.watchType == "" { c.UI.Error("Watch type must be specified") c.UI.Error("") c.UI.Error(c.Help()) return 1 } // Compile the watch parameters params := make(map[string]interface{}) if c.watchType != "" { params["type"] = c.watchType } if c.HTTPDatacenter() != "" { params["datacenter"] = c.HTTPDatacenter() } if c.HTTPToken() != "" { params["token"] = c.HTTPToken() } if c.key != "" { params["key"] = c.key } if c.prefix != "" { params["prefix"] = c.prefix } if c.service != "" { params["service"] = c.service } if c.tag != "" { params["tag"] = c.tag } if c.HTTPStale() { params["stale"] = c.HTTPStale() } if c.state != "" { params["state"] = c.state } if c.name != "" { params["name"] = c.name } if c.passingOnly != "" { b, err := strconv.ParseBool(c.passingOnly) if err != nil { c.UI.Error(fmt.Sprintf("Failed to parse passingonly flag: %s", err)) return 1 } params["passingonly"] = b } // Create the watch wp, err := watch.Parse(params) if err != nil { c.UI.Error(fmt.Sprintf("%s", err)) return 1 } // Create and test the HTTP client client, err := c.HTTPClient() if err != nil { c.UI.Error(fmt.Sprintf("Error connecting to Consul agent: %s", err)) return 1 } _, err = client.Agent().NodeName() if err != nil { c.UI.Error(fmt.Sprintf("Error querying Consul agent: %s", err)) return 1 } // Setup handler // errExit: // 0: false // 1: true errExit := 0 if len(c.FlagSet.Args()) == 0 { wp.Handler = func(idx uint64, data interface{}) { defer wp.Stop() buf, err := json.MarshalIndent(data, "", " ") if err != nil { c.UI.Error(fmt.Sprintf("Error encoding output: %s", err)) errExit = 1 } c.UI.Output(string(buf)) } } else { wp.Handler = func(idx uint64, data interface{}) { doneCh := make(chan struct{}) defer close(doneCh) logFn := func(err error) { c.UI.Error(fmt.Sprintf("Warning, could not forward signal: %s", err)) } // Create the command var buf bytes.Buffer var err error var cmd *exec.Cmd if !c.shell { cmd, err = agent.ExecSubprocess(c.FlagSet.Args()) } else { cmd, err = agent.ExecScript(strings.Join(c.FlagSet.Args(), " ")) } if err != nil { c.UI.Error(fmt.Sprintf("Error executing handler: %s", err)) goto ERR } cmd.Env = append(os.Environ(), "CONSUL_INDEX="+strconv.FormatUint(idx, 10), ) // Encode the input if err = json.NewEncoder(&buf).Encode(data); err != nil { c.UI.Error(fmt.Sprintf("Error encoding output: %s", err)) goto ERR } cmd.Stdin = &buf cmd.Stdout = os.Stdout cmd.Stderr = os.Stderr // Run the handler. if err := cmd.Start(); err != nil { c.UI.Error(fmt.Sprintf("Error starting handler: %s", err)) goto ERR } // Set up signal forwarding. agent.ForwardSignals(cmd, logFn, doneCh) // Wait for the handler to complete. if err := cmd.Wait(); err != nil { c.UI.Error(fmt.Sprintf("Error executing handler: %s", err)) goto ERR } return ERR: wp.Stop() errExit = 1 } } // Watch for a shutdown go func() { <-c.ShutdownCh wp.Stop() os.Exit(0) }() // Run the watch if err := wp.Run(c.HTTPAddr()); err != nil { c.UI.Error(fmt.Sprintf("Error querying Consul agent: %s", err)) return 1 } return errExit } func (c *WatchCommand) Synopsis() string { return "Watch for changes in Consul" }