- in-memory message queue system
- runs stand-alone (download), via Docker or embedded
- Amazon SQS-compatible interface
- fully asynchronous implementation, no blocking calls
Created and maintained by
ElasticMQ is a message queue system, offering an actor-based Scala and an SQS-compatible REST (query) interface.
ElasticMQ follows the semantics of SQS. Messages are received by polling the queue. When a message is received, it is blocked for a specified amount of time (the visibility timeout). If the message isn't deleted during that time, it will be again available for delivery. Moreover, queues and messages can be configured to always deliver messages with a delay.
The focus in SQS (and ElasticMQ) is to make sure that the messages are delivered. It may happen, however, that a message is delivered twice (if, for example, a client dies after receiving a message and processing it, but before deleting). That's why clients of ElasticMQ (and Amazon SQS) should be idempotent.
As ElasticMQ implements a subset of the SQS query (REST) interface, it is a great SQS alternative both for testing purposes (ElasticMQ is easily embeddable) and for creating systems which work both within and outside of the Amazon infrastructure.
The future will most probably bring even more exciting features :).
- Issues
- Forum (discussions, help): Google group.
- (old) blog
You can download the stand-alone distribution here: https://s3/.../elasticmq-server-0.14.6.jar
Java 8 or above is required for running the server.
Simply run the jar and you should get a working server, which binds to localhost:9324:
java -jar elasticmq-server-0.14.6.jar
ElasticMQ uses Typesafe Config for configuration. To specify custom
configuration values, create a file (e.g. custom.conf), fill it in with the desired values, and pass it to the server:
java -Dconfig.file=custom.conf -jar elasticmq-server-0.14.6.jar
The config file may contain any configuration for Akka and ElasticMQ. Current ElasticMQ configuration values are:
include classpath("application.conf")
// What is the outside visible address of this ElasticMQ node
// Used to create the queue URL (may be different from bind address!)
node-address {
protocol = http
host = localhost
port = 9324
context-path = ""
}
rest-sqs {
enabled = true
bind-port = 9324
bind-hostname = "0.0.0.0"
// Possible values: relaxed, strict
sqs-limits = strict
}
// Should the node-address be generated from the bind port/hostname
// Set this to true e.g. when assigning port automatically by using port 0.
generate-node-address = false
queues {
// See next section
}
You can also provide an alternative Logback configuration file (the default is configured to log INFO logs and above to the console):
java -Dlogback.configurationFile=my_logback.xml -jar elasticmq-server-0.14.6.jar
Some of the responses include a queue URL. By default the urls will use http://localhost:9324 as the base URL.
To customize, you should properly set the protocol/host/port/context in the node-address setting (see above).
You can also set node-address.host to a special value, "*", which will cause any queue URLs created during a request
to use the path of the incoming request. This might be useful e.g. in containerized (Docker) deployments.
Note that changing the bind-port and bind-hostname settings does not affect the queue URLs in any way unless
generate-node-address is true. In that case, the bind host/port are used to create the node address. This is
useful when the port should be automatically assigned (use port 0 in such case, the selected port will be
visible in the logs).
Queues can be automatically created on startup by providing appropriate configuration:
The queues are specified in a custom configuration file. For example, create a custom.conf file with the following:
include classpath("application.conf")
queues {
queue1 {
defaultVisibilityTimeout = 10 seconds
delay = 5 seconds
receiveMessageWait = 0 seconds
deadLettersQueue {
name = "queue1-dead-letters"
maxReceiveCount = 3 // from 1 to 1000
}
fifo = false
contentBasedDeduplication = false
copyTo = "audit-queue-name"
moveTo = "redirect-queue-name"
tags {
tag1 = "tagged1"
tag2 = "tagged2"
}
}
queue1-dead-letters { }
audit-queue-name { }
redirect-queue-name { }
}
All attributes are optional (except name and maxReceiveCount when a deadLettersQueue is defined).
copyTo and moveTo attributes allow to achieve behavior that might be useful primarily for integration testing scenarios -
all messages could be either duplicated (using copyTo attribute) or redirected (using moveTo attribute) to another queue.
val server = SQSRestServerBuilder.start()
// ... use ...
server.stopAndWait()
If you need to bind to a different host/port, there are configuration methods on the builder:
val server = SQSRestServerBuilder.withPort(9325).withInterface("localhost").start()
// ... use ...
server.stopAndWait()
You can also set a dynamic port with a port value of 0 or by using the method withDynamicPort. To retrieve the port (and other configuration) when using a dynamic port value you can access the server via waitUntilStarted for example:
val server = SQSRestServerBuilder.withDynamicPort().start()
server.waitUntilStarted().localAddress().getPort()
You can also provide a custom ActorSystem; for details see the javadocs.
Embedded ElasticMQ can be used from any JVM-based language (Java, Scala, etc.).
To use Amazon Java SDK as an interface to an ElasticMQ server you just need to change the endpoint:
String endpoint = "http://localhost:9324";
String region = "elasticmq";
String accessKey = "x";
String secretKey = "x";
AmazonSQS client = AmazonSQSClientBuilder.standard()
.withCredentials(new AWSStaticCredentialsProvider(new BasicAWSCredentials(accessKey, secretKey)))
.withEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(endpoint, region))
.build();
The endpoint value should be the same address as the NodeAddress provided as an argument to
SQSRestServerBuilder or in the configuration file.
The rest-sqs-testing-amazon-java-sdk module contains some more usage examples.
To use Amazon boto as an interface to an ElasticMQ server you set up the connection using:
region = boto.sqs.regioninfo.RegionInfo(name='elasticmq',
endpoint=sqs_endpoint)
conn = boto.connect_sqs(aws_access_key_id='x',
aws_secret_access_key='x',
is_secure=False,
port=sqs_port,
region=region)
where sqs_endpoint and sqs_port are the host and port.
The boto3 interface is different:
client = boto3.resource('sqs',
endpoint_url='http://localhost:9324',
region_name='elasticmq',
aws_secret_access_key='x',
aws_access_key_id='x',
use_ssl=False)
queue = client.get_queue_by_name(QueueName='queue1')
A Docker image is built on each release an pushed as softwaremill/elasticmq.
The image uses default configuration. Custom configuration can be provided (e.g. to change the port, or create queues on startup) by creating a custom configuration file (see above) and using it when running the container:
docker run -v `pwd`/custom.conf:/opt/elasticmq.conf softwaremill/elasticmq
// Scala 2.12 and 2.11
val elasticmqSqs = "org.elasticmq" %% "elasticmq-rest-sqs" % "0.14.6"
If you don't want the SQS interface, but just use the actors directly, you can add a dependency only to the core
module:
val elasticmqCore = "org.elasticmq" %% "elasticmq-core" % "0.14.6"
If you want to use a snapshot version, you will need to add the https://oss.sonatype.org/content/repositories/snapshots/ repository to your configuration.
Dependencies:
<dependency>
<groupId>org.elasticmq</groupId>
<artifactId>elasticmq-rest-sqs_2.11</artifactId>
<version>0.14.6</version>
</dependency>
If you want to use a snapshot version, you will need to add the https://oss.sonatype.org/content/repositories/snapshots/ repository to your configuration.
Stable: 0.14.6, 0.8.12
Development: 0.14.6-SNAPSHOT
ElasticMQ uses Slf4j for logging. By default no logger backend is included as a dependency, however Logback is recommended.
Tests done on a 2012 MBP, 2.6GHz, 16GB RAM, no replication. Throughput is in messages per second (messages are small).
Directly accessing the client:
Running test for [in-memory], iterations: 10, msgs in iteration: 100000, thread count: 1.
Overall in-memory throughput: 21326.054040
Running test for [in-memory], iterations: 10, msgs in iteration: 100000, thread count: 2.
Overall in-memory throughput: 26292.956117
Running test for [in-memory], iterations: 10, msgs in iteration: 100000, thread count: 10.
Overall in-memory throughput: 25591.155697
Through the SQS REST interface:
Running test for [rest-sqs + in-memory], iterations: 10, msgs in iteration: 1000, thread count: 20.
Overall rest-sqs + in-memory throughput: 2540.553587
Running test for [rest-sqs + in-memory], iterations: 10, msgs in iteration: 1000, thread count: 40.
Overall rest-sqs + in-memory throughput: 2600.002600
Note that both the client and the server were on the same machine.
Test class: org.elasticmq.performance.LocalPerformanceTest.
To build and run with debug (this will listen for a remote debugger on port 5005):
~/workspace/elasticmq $ sbt -jvm-debug 5005
> project elasticmq-server
> run
To build a jar-with-dependencies:
~/workspace/elasticmq $ sbt
> project elasticmq-server
> assembly
To run the tests:
~/workspace/elasticmq $ sbt test
To check the coverage reports:
~/workspace/elasticmq $ sbt
> coverage
> tests
> coverageReport
> coverageAggregate
Although it's mostly only the core project that is relevant for coverage testing, each project's report can be found in their target directory:
- core/target/scala-2.12/scoverage-report/index.html
- common-test/target/scala-2.12/scoverage-report/index.html
- rest/rest-sqs/target/scala-2.12/scoverage-report/index.html
- server/target/scala-2.12/scoverage-report/index.html
The aggregate report can be found at target/scala-2.12/scoverage-report/index.html
- Core: Scala and Akka.
- Rest server: Akka HTTP, a high-performance, asynchronous, REST/HTTP toolkit.
- Testing the SQS interface: Amazon Java SDK;
see the
rest-sqs-testing-amazon-java-sdkmodule for the testsuite.