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watch.go
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watch.go
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package watch
import (
"bytes"
"encoding/json"
"flag"
"fmt"
"os"
osexec "os/exec"
"strconv"
"strings"
"github.com/hashicorp/consul/agent"
"github.com/hashicorp/consul/agent/exec"
"github.com/hashicorp/consul/api"
consulwatch "github.com/hashicorp/consul/api/watch"
"github.com/hashicorp/consul/command/flags"
"github.com/mitchellh/cli"
)
func New(ui cli.Ui, shutdownCh <-chan struct{}) *cmd {
c := &cmd{UI: ui, shutdownCh: shutdownCh}
c.init()
return c
}
type cmd struct {
UI cli.Ui
flags *flag.FlagSet
http *flags.HTTPFlags
help string
shutdownCh <-chan struct{}
// flags
watchType string
key string
prefix string
service string
tag []string
passingOnly string
state string
name string
shell bool
}
func (c *cmd) init() {
c.flags = flag.NewFlagSet("", flag.ContinueOnError)
c.flags.StringVar(&c.watchType, "type", "",
"Specifies the watch type. One of key, keyprefix, services, nodes, "+
"service, checks, or event.")
c.flags.StringVar(&c.key, "key", "",
"Specifies the key to watch. Only for 'key' type.")
c.flags.StringVar(&c.prefix, "prefix", "",
"Specifies the key prefix to watch. Only for 'keyprefix' type.")
c.flags.StringVar(&c.service, "service", "",
"Specifies the service to watch. Required for 'service' type, "+
"optional for 'checks' type.")
c.flags.Var((*flags.AppendSliceValue)(&c.tag), "tag", "Specifies the service tag(s) to filter on. "+
"Optional for 'service' type. May be specified multiple times")
c.flags.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.flags.BoolVar(&c.shell, "shell", true,
"Use a shell to run the command (can set a custom shell via the SHELL "+
"environment variable).")
c.flags.StringVar(&c.state, "state", "",
"Specifies the states to watch. Optional for 'checks' type.")
c.flags.StringVar(&c.name, "name", "",
"Specifies an event name to watch. Only for 'event' type.")
c.http = &flags.HTTPFlags{}
flags.Merge(c.flags, c.http.ClientFlags())
flags.Merge(c.flags, c.http.ServerFlags())
c.help = flags.Usage(help, c.flags)
}
func (c *cmd) loadToken() (string, error) {
httpCfg := api.DefaultConfig()
c.http.MergeOntoConfig(httpCfg)
// Trigger the Client init to do any last-minute updates to the Config.
if _, err := api.NewClient(httpCfg); err != nil {
return "", err
}
return httpCfg.Token, nil
}
func (c *cmd) Run(args []string) int {
if err := c.flags.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
}
token, err := c.loadToken()
if err != nil {
c.UI.Error(err.Error())
return 1
}
// Compile the watch parameters
params := make(map[string]interface{})
if c.watchType != "" {
params["type"] = c.watchType
}
if c.http.Datacenter() != "" {
params["datacenter"] = c.http.Datacenter()
}
if token != "" {
params["token"] = token
}
if c.key != "" {
params["key"] = c.key
}
if c.prefix != "" {
params["prefix"] = c.prefix
}
if c.service != "" {
params["service"] = c.service
}
if len(c.tag) > 0 {
params["tag"] = c.tag
}
if c.http.Stale() {
params["stale"] = c.http.Stale()
}
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 := consulwatch.Parse(params)
if err != nil {
c.UI.Error(fmt.Sprintf("%s", err))
return 1
}
if strings.HasPrefix(wp.Type, "connect_") || strings.HasPrefix(wp.Type, "agent_") {
c.UI.Error(fmt.Sprintf("Type %s is not supported in the CLI tool", wp.Type))
return 1
}
// Create and test the HTTP client
client, err := c.http.APIClient()
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.flags.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 *osexec.Cmd
if !c.shell {
cmd, err = exec.Subprocess(c.flags.Args())
} else {
cmd, err = exec.Script(strings.Join(c.flags.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.http.Addr()); err != nil {
c.UI.Error(fmt.Sprintf("Error querying Consul agent: %s", err))
return 1
}
return errExit
}
func (c *cmd) Synopsis() string {
return synopsis
}
func (c *cmd) Help() string {
return c.help
}
const synopsis = "Watch for changes in Consul"
const help = `
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.
`