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examples_test.go
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// Copyright (c) 2021 VMware, Inc. or its affiliates. All Rights Reserved.
// Copyright (c) 2012-2021, Sean Treadway, SoundCloud Ltd.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package amqp091_test
import (
"crypto/tls"
"crypto/x509"
"io/ioutil"
"log"
"net"
"runtime"
"time"
amqp "github.com/rabbitmq/amqp091-go"
)
func ExampleConfig_timeout() {
// Provide your own anonymous Dial function that delegates to net.DialTimout
// for custom timeouts
conn, err := amqp.DialConfig("amqp:///", amqp.Config{
Dial: func(network, addr string) (net.Conn, error) {
return net.DialTimeout(network, addr, 2*time.Second)
},
})
log.Printf("conn: %v, err: %v", conn, err)
}
func ExampleDialTLS() {
// This example assume you have a RabbitMQ node running on localhost
// with TLS enabled.
//
// The easiest way to create the CA, certificates and keys required for these
// examples is by using tls-gen: https://github.com/michaelklishin/tls-gen
//
// A comprehensive RabbitMQ TLS guide can be found at
// http://www.rabbitmq.com/ssl.html
//
// Once you have the required TLS files in place, use the following
// rabbitmq.config example for the RabbitMQ node that you will run on
// localhost:
//
// [
// {rabbit, [
// {tcp_listeners, []}, % listens on 127.0.0.1:5672
// {ssl_listeners, [5671]}, % listens on 0.0.0.0:5671
// {ssl_options, [{cacertfile,"/path/to/your/testca/cacert.pem"},
// {certfile,"/path/to/your/server/cert.pem"},
// {keyfile,"/path/to/your/server/key.pem"},
// {verify,verify_peer},
// {fail_if_no_peer_cert,true}]}
// ]}
// ].
//
//
// In the above rabbitmq.config example, we are disabling the plain AMQP port
// and verifying that clients and fail if no certificate is presented.
//
// The self-signing certificate authority's certificate (cacert.pem) must be
// included in the RootCAs to be trusted, otherwise the server certificate
// will fail certificate verification.
//
// Alternatively to adding it to the tls.Config. you can add the CA's cert to
// your system's root CAs. The tls package will use the system roots
// specific to each support OS. Under OS X, add (drag/drop) cacert.pem
// file to the 'Certificates' section of KeyChain.app to add and always
// trust. You can also add it via the command line:
//
// security add-certificate testca/cacert.pem
// security add-trusted-cert testca/cacert.pem
//
// If you depend on the system root CAs, then use nil for the RootCAs field
// so the system roots will be loaded instead.
//
// Server names are validated by the crypto/tls package, so the server
// certificate must be made for the hostname in the URL. Find the commonName
// (CN) and make sure the hostname in the URL matches this common name. Per
// the RabbitMQ instructions (or tls-gen) for a self-signed cert, this defaults to the
// current hostname.
//
// openssl x509 -noout -in /path/to/certificate.pem -subject
//
// If your server name in your certificate is different than the host you are
// connecting to, set the hostname used for verification in
// ServerName field of the tls.Config struct.
cfg := new(tls.Config)
// see at the top
cfg.RootCAs = x509.NewCertPool()
if ca, err := ioutil.ReadFile("testca/cacert.pem"); err == nil {
cfg.RootCAs.AppendCertsFromPEM(ca)
}
// Move the client cert and key to a location specific to your application
// and load them here.
if cert, err := tls.LoadX509KeyPair("client/cert.pem", "client/key.pem"); err == nil {
cfg.Certificates = append(cfg.Certificates, cert)
}
// see a note about Common Name (CN) at the top
conn, err := amqp.DialTLS("amqps://server-name-from-certificate/", cfg)
log.Printf("conn: %v, err: %v", conn, err)
}
func ExampleChannel_Confirm_bridge() {
// This example acts as a bridge, shoveling all messages sent from the source
// exchange "log" to destination exchange "log".
// Confirming publishes can help from overproduction and ensure every message
// is delivered.
// Setup the source of the store and forward
source, err := amqp.Dial("amqp://source/")
if err != nil {
log.Fatalf("connection.open source: %s", err)
}
defer source.Close()
chs, err := source.Channel()
if err != nil {
log.Fatalf("channel.open source: %s", err)
}
if err := chs.ExchangeDeclare("log", "topic", true, false, false, false, nil); err != nil {
log.Fatalf("exchange.declare destination: %s", err)
}
if _, err := chs.QueueDeclare("remote-tee", true, true, false, false, nil); err != nil {
log.Fatalf("queue.declare source: %s", err)
}
if err := chs.QueueBind("remote-tee", "#", "logs", false, nil); err != nil {
log.Fatalf("queue.bind source: %s", err)
}
shovel, err := chs.Consume("remote-tee", "shovel", false, false, false, false, nil)
if err != nil {
log.Fatalf("basic.consume source: %s", err)
}
// Setup the destination of the store and forward
destination, err := amqp.Dial("amqp://destination/")
if err != nil {
log.Fatalf("connection.open destination: %s", err)
}
defer destination.Close()
chd, err := destination.Channel()
if err != nil {
log.Fatalf("channel.open destination: %s", err)
}
if err := chd.ExchangeDeclare("log", "topic", true, false, false, false, nil); err != nil {
log.Fatalf("exchange.declare destination: %s", err)
}
// Buffer of 1 for our single outstanding publishing
confirms := chd.NotifyPublish(make(chan amqp.Confirmation, 1))
if err := chd.Confirm(false); err != nil {
log.Fatalf("confirm.select destination: %s", err)
}
// Now pump the messages, one by one, a smarter implementation
// would batch the deliveries and use multiple ack/nacks
for {
msg, ok := <-shovel
if !ok {
log.Fatalf("source channel closed, see the reconnect example for handling this")
}
err = chd.Publish("logs", msg.RoutingKey, false, false, amqp.Publishing{
// Copy all the properties
ContentType: msg.ContentType,
ContentEncoding: msg.ContentEncoding,
DeliveryMode: msg.DeliveryMode,
Priority: msg.Priority,
CorrelationId: msg.CorrelationId,
ReplyTo: msg.ReplyTo,
Expiration: msg.Expiration,
MessageId: msg.MessageId,
Timestamp: msg.Timestamp,
Type: msg.Type,
UserId: msg.UserId,
AppId: msg.AppId,
// Custom headers
Headers: msg.Headers,
// And the body
Body: msg.Body,
})
if err != nil {
msg.Nack(false, false)
log.Fatalf("basic.publish destination: %+v", msg)
}
// only ack the source delivery when the destination acks the publishing
if confirmed := <-confirms; confirmed.Ack {
msg.Ack(false)
} else {
msg.Nack(false, false)
}
}
}
func ExampleChannel_Consume() {
// Connects opens an AMQP connection from the credentials in the URL.
conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
if err != nil {
log.Fatalf("connection.open: %s", err)
}
defer conn.Close()
c, err := conn.Channel()
if err != nil {
log.Fatalf("channel.open: %s", err)
}
// We declare our topology on both the publisher and consumer to ensure they
// are the same. This is part of AMQP being a programmable messaging model.
//
// See the Channel.Publish example for the complimentary declare.
err = c.ExchangeDeclare("logs", "topic", true, false, false, false, nil)
if err != nil {
log.Fatalf("exchange.declare: %s", err)
}
// Establish our queue topologies that we are responsible for
type bind struct {
queue string
key string
}
bindings := []bind{
{"page", "alert"},
{"email", "info"},
{"firehose", "#"},
}
for _, b := range bindings {
_, err = c.QueueDeclare(b.queue, true, false, false, false, nil)
if err != nil {
log.Fatalf("queue.declare: %v", err)
}
err = c.QueueBind(b.queue, b.key, "logs", false, nil)
if err != nil {
log.Fatalf("queue.bind: %v", err)
}
}
// Set our quality of service. Since we're sharing 3 consumers on the same
// channel, we want at least 3 messages in flight.
err = c.Qos(3, 0, false)
if err != nil {
log.Fatalf("basic.qos: %v", err)
}
// Establish our consumers that have different responsibilities. Our first
// two queues do not ack the messages on the server, so require to be acked
// on the client.
pages, err := c.Consume("page", "pager", false, false, false, false, nil)
if err != nil {
log.Fatalf("basic.consume: %v", err)
}
go func() {
for log := range pages {
// ... this consumer is responsible for sending pages per log
log.Ack(false)
}
}()
// Notice how the concern for which messages arrive here are in the AMQP
// topology and not in the queue. We let the server pick a consumer tag this
// time.
emails, err := c.Consume("email", "", false, false, false, false, nil)
if err != nil {
log.Fatalf("basic.consume: %v", err)
}
go func() {
for log := range emails {
// ... this consumer is responsible for sending emails per log
log.Ack(false)
}
}()
// This consumer requests that every message is acknowledged as soon as it's
// delivered.
firehose, err := c.Consume("firehose", "", true, false, false, false, nil)
if err != nil {
log.Fatalf("basic.consume: %v", err)
}
// To show how to process the items in parallel, we'll use a work pool.
for i := 0; i < runtime.NumCPU(); i++ {
go func(work <-chan amqp.Delivery) {
for range work {
// ... this consumer pulls from the firehose and doesn't need to acknowledge
}
}(firehose)
}
// Wait until you're ready to finish, could be a signal handler here.
time.Sleep(10 * time.Second)
// Cancelling a consumer by name will finish the range and gracefully end the
// goroutine
err = c.Cancel("pager", false)
if err != nil {
log.Fatalf("basic.cancel: %v", err)
}
// deferred closing the Connection will also finish the consumer's ranges of
// their delivery chans. If you need every delivery to be processed, make
// sure to wait for all consumers goroutines to finish before exiting your
// process.
}
func ExampleChannel_Publish() {
// Connects opens an AMQP connection from the credentials in the URL.
conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
if err != nil {
log.Fatalf("connection.open: %s", err)
}
// This waits for a server acknowledgment which means the sockets will have
// flushed all outbound publishings prior to returning. It's important to
// block on Close to not lose any publishings.
defer conn.Close()
c, err := conn.Channel()
if err != nil {
log.Fatalf("channel.open: %s", err)
}
// We declare our topology on both the publisher and consumer to ensure they
// are the same. This is part of AMQP being a programmable messaging model.
//
// See the Channel.Consume example for the complimentary declare.
err = c.ExchangeDeclare("logs", "topic", true, false, false, false, nil)
if err != nil {
log.Fatalf("exchange.declare: %v", err)
}
// Prepare this message to be persistent. Your publishing requirements may
// be different.
msg := amqp.Publishing{
DeliveryMode: amqp.Persistent,
Timestamp: time.Now(),
ContentType: "text/plain",
Body: []byte("Go Go AMQP!"),
}
// This is not a mandatory delivery, so it will be dropped if there are no
// queues bound to the logs exchange.
err = c.Publish("logs", "info", false, false, msg)
if err != nil {
// Since publish is asynchronous this can happen if the network connection
// is reset or if the server has run out of resources.
log.Fatalf("basic.publish: %v", err)
}
}
func publishAllTheThings(conn *amqp.Connection) {
// ... snarf snarf, barf barf
}
func ExampleConnection_NotifyBlocked() {
// Simply logs when the server throttles the TCP connection for publishers
// Test this by tuning your server to have a low memory watermark:
// rabbitmqctl set_vm_memory_high_watermark 0.00000001
conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
if err != nil {
log.Fatalf("connection.open: %s", err)
}
defer conn.Close()
blockings := conn.NotifyBlocked(make(chan amqp.Blocking))
go func() {
for b := range blockings {
if b.Active {
log.Printf("TCP blocked: %q", b.Reason)
} else {
log.Printf("TCP unblocked")
}
}
}()
// Your application domain channel setup publishings
publishAllTheThings(conn)
}