mirror of
https://github.com/nats-io/nats.go.git
synced 2025-10-07 17:42:09 +08:00
141 lines
3.6 KiB
Go
141 lines
3.6 KiB
Go
// Copyright 2012-2022 The NATS Authors
|
|
// 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 main
|
|
|
|
import (
|
|
"flag"
|
|
"log"
|
|
"os"
|
|
"runtime"
|
|
"time"
|
|
|
|
"github.com/nats-io/nats.go"
|
|
)
|
|
|
|
// NOTE: Can test with demo servers.
|
|
// nats-sub -s demo.nats.io <subject>
|
|
|
|
func usage() {
|
|
log.Printf("Usage: nats-sub [-s server] [-creds file] [-nkey file] [-tlscert file] [-tlskey file] [-tlscacert file] [-t] <subject>\n")
|
|
flag.PrintDefaults()
|
|
}
|
|
|
|
func showUsageAndExit(exitcode int) {
|
|
usage()
|
|
os.Exit(exitcode)
|
|
}
|
|
|
|
func printMsg(m *nats.Msg, i int) {
|
|
log.Printf("[#%d] Received on [%s]: '%s'", i, m.Subject, string(m.Data))
|
|
}
|
|
|
|
func main() {
|
|
var urls = flag.String("s", nats.DefaultURL, "The nats server URLs (separated by comma)")
|
|
var userCreds = flag.String("creds", "", "User Credentials File")
|
|
var nkeyFile = flag.String("nkey", "", "NKey Seed File")
|
|
var tlsClientCert = flag.String("tlscert", "", "TLS client certificate file")
|
|
var tlsClientKey = flag.String("tlskey", "", "Private key file for client certificate")
|
|
var tlsCACert = flag.String("tlscacert", "", "CA certificate to verify peer against")
|
|
var showTime = flag.Bool("t", false, "Display timestamps")
|
|
var showHelp = flag.Bool("h", false, "Show help message")
|
|
|
|
log.SetFlags(0)
|
|
flag.Usage = usage
|
|
flag.Parse()
|
|
|
|
if *showHelp {
|
|
showUsageAndExit(0)
|
|
}
|
|
|
|
args := flag.Args()
|
|
if len(args) != 1 {
|
|
showUsageAndExit(1)
|
|
}
|
|
|
|
// Connect Options.
|
|
opts := []nats.Option{nats.Name("NATS Sample Subscriber")}
|
|
opts = setupConnOptions(opts)
|
|
|
|
if *userCreds != "" && *nkeyFile != "" {
|
|
log.Fatal("specify -seed or -creds")
|
|
}
|
|
|
|
// Use UserCredentials
|
|
if *userCreds != "" {
|
|
opts = append(opts, nats.UserCredentials(*userCreds))
|
|
}
|
|
|
|
// Use TLS client authentication
|
|
if *tlsClientCert != "" && *tlsClientKey != "" {
|
|
opts = append(opts, nats.ClientCert(*tlsClientCert, *tlsClientKey))
|
|
}
|
|
|
|
// Use specific CA certificate
|
|
if *tlsCACert != "" {
|
|
opts = append(opts, nats.RootCAs(*tlsCACert))
|
|
}
|
|
|
|
// Use Nkey authentication.
|
|
if *nkeyFile != "" {
|
|
opt, err := nats.NkeyOptionFromSeed(*nkeyFile)
|
|
if err != nil {
|
|
log.Fatal(err)
|
|
}
|
|
opts = append(opts, opt)
|
|
}
|
|
|
|
// Connect to NATS
|
|
nc, err := nats.Connect(*urls, opts...)
|
|
if err != nil {
|
|
log.Fatal(err)
|
|
}
|
|
|
|
subj, i := args[0], 0
|
|
|
|
nc.Subscribe(subj, func(msg *nats.Msg) {
|
|
i += 1
|
|
printMsg(msg, i)
|
|
})
|
|
nc.Flush()
|
|
|
|
if err := nc.LastError(); err != nil {
|
|
log.Fatal(err)
|
|
}
|
|
|
|
log.Printf("Listening on [%s]", subj)
|
|
if *showTime {
|
|
log.SetFlags(log.LstdFlags)
|
|
}
|
|
|
|
runtime.Goexit()
|
|
}
|
|
|
|
func setupConnOptions(opts []nats.Option) []nats.Option {
|
|
totalWait := 10 * time.Minute
|
|
reconnectDelay := time.Second
|
|
|
|
opts = append(opts, nats.ReconnectWait(reconnectDelay))
|
|
opts = append(opts, nats.MaxReconnects(int(totalWait/reconnectDelay)))
|
|
opts = append(opts, nats.DisconnectErrHandler(func(nc *nats.Conn, err error) {
|
|
log.Printf("Disconnected due to:%s, will attempt reconnects for %.0fm", err, totalWait.Minutes())
|
|
}))
|
|
opts = append(opts, nats.ReconnectHandler(func(nc *nats.Conn) {
|
|
log.Printf("Reconnected [%s]", nc.ConnectedUrl())
|
|
}))
|
|
opts = append(opts, nats.ClosedHandler(func(nc *nats.Conn) {
|
|
log.Fatalf("Exiting: %v", nc.LastError())
|
|
}))
|
|
return opts
|
|
}
|