Akka Management

Akka Management is the core module of the management utilities which provides a central HTTP endpoint for Akka management extensions.

Project Info

Dependencies

The main Akka Management dependency is called akka-management. By itself however it does not provide any capabilities, and you have to combine it with the management extension libraries that you want to make use of (e.g. cluster http management, or cluster bootstrap). This design choice enables users to include only the minimal set of features they actually want to use (and load) in their project.

The Akka dependencies are available from Akka’s library repository. To access them there, you need to configure the URL for this repository.

sbt

resolvers += "Akka library repository".at("https://repo.akka.io/maven")

Gradle

repositories {
    mavenCentral()
    maven {
        url "https://repo.akka.io/maven"
    }
}

Maven

<project>
  ...
  <repositories>
    <repository>
      <id>akka-repository</id>
      <name>Akka library repository</name>
      <url>https://repo.akka.io/maven</url>
    </repository>
  </repositories>
</project>

Additionally, add the dependency as below.

sbt

val AkkaManagementVersion = "1.6.0"
libraryDependencies += "com.lightbend.akka.management" %% "akka-management" % AkkaManagementVersion

Gradle

def versions = [
  AkkaManagementVersion: "1.6.0",
  ScalaBinary: "2.13"
]
dependencies {
  implementation "com.lightbend.akka.management:akka-management_${versions.ScalaBinary}:${versions.AkkaManagementVersion}"
}

Maven

<properties>
  <akka.management.version>1.6.0</akka.management.version>
  <scala.binary.version>2.13</scala.binary.version>
</properties>
<dependencies>
  <dependency>
    <groupId>com.lightbend.akka.management</groupId>
    <artifactId>akka-management_${scala.binary.version}</artifactId>
    <version>${akka.management.version}</version>
  </dependency>
</dependencies>

And in addition to that, include all of the dependencies for the features you’d like to use, like akka-management-bootstrap etc. Refer to each extensions documentation page to learn about how to configure and use it.

Akka Management can be used with Akka 2.10.0 or later. You have to override the following Akka dependencies by defining them explicitly in your build and define the Akka version to the one that you are using. Latest patch version of Akka is recommended and a later version than 2.10.0 can be used.

sbt

val AkkaVersion = "2.10.0"
libraryDependencies += "com.typesafe.akka" %% "akka-stream" % AkkaVersion

Gradle

def versions = [
  AkkaVersion: "2.10.0",
  ScalaBinary: "2.13"
]
dependencies {
  implementation "com.typesafe.akka:akka-stream_${versions.ScalaBinary}:${versions.AkkaVersion}"
}

Maven

<properties>
  <akka.version>2.10.0</akka.version>
  <scala.binary.version>2.13</scala.binary.version>
</properties>
<dependencies>
  <dependency>
    <groupId>com.typesafe.akka</groupId>
    <artifactId>akka-stream_${scala.binary.version}</artifactId>
    <version>${akka.version}</version>
  </dependency>
</dependencies>

Basic Usage

Remember that Akka Management does not start automatically and the routes will only be exposed once you trigger:

Scala

copysourceimport akka.management.scaladsl.AkkaManagement

AkkaManagement(system).start()

Java

copysourceimport akka.management.javadsl.AkkaManagement;

AkkaManagement.get(system).start();

This allows users to prepare anything further before exposing routes for the bootstrap joining process and other purposes.

Remember to call stop method preferably in Coordinated Shutdown. See the Lagom example.

Basic Configuration

You can configure hostname and port to use for the HTTP Cluster management by overriding the following:

copysourceakka.management.http.hostname = "127.0.0.1"
akka.management.http.port = 8558

Note that the default value for hostname is InetAddress.getLocalHost.getHostAddress, which may or may not evaluate to 127.0.0.1.

When running Akka nodes behind NATs or inside docker containers in bridge mode, it is necessary to set different hostname and port number to bind for the HTTP Server for Http Cluster Management:

application.conf

  # Get hostname from environmental variable HOST
  akka.management.http.hostname = ${HOST}
  # Use port 8558 by default, but use environment variable PORT_8558 if it is defined
  akka.management.http.port = 8558
  akka.management.http.port = ${?PORT_8558}
  # Bind to 0.0.0.0:8558 'internally': 
  akka.management.http.bind-hostname = 0.0.0.0
  akka.management.http.bind-port = 8558

It is also possible to modify the base path of the API, by setting the appropriate value in application.conf:

application.conf

akka.management.http.base-path = "myClusterName"

In this example, with this configuration, then the Akka Management routes will will be exposed at under the /myClusterName/..., base path. For example, when using Akka Cluster Management routes the members information would then be available under /myClusterName/shards/{name} etc.

Read only routes

By default extensions to Akka Management should only provide read only routes. This can be changed via setting akka.management.http.route-providers-read-only to false. Each extension can access the value of this property via ManagementRouteProviderSettings.readOnly to decide which routes to expose.

For example the cluster-http extension only provides read only access to Cluster membership but if route-provider-read-only is set to false additional endpoints for managing the cluster are exposed e.g. downing members.

Configuring Security

The non-secured usage of the module is as follows:

Scala

copysourceimport akka.management.scaladsl.AkkaManagement

AkkaManagement(system).start()

Java

copysourceimport akka.management.javadsl.AkkaManagement;

AkkaManagement.get(system).start();

Enabling TLS/SSL (HTTPS) for Cluster HTTP Management

To enable SSL you need to provide an SSLContext. You can find more information about it in Server HTTPS Support.

Scala

copysourceval management = AkkaManagement(system)

val httpsServer: HttpsConnectionContext = ConnectionContext.httpsServer(sslContext)

val started = management.start(_.withHttpsConnectionContext(httpsServer))

Java

copysourceAkkaManagement management = AkkaManagement.get(system);

HttpsConnectionContext https = ConnectionContext.httpsServer(sslContext);
management.start(settings -> settings.withHttpsConnectionContext(https));

You can also refer to AkkaManagementHttpEndpointSpec where a full example configuring the HTTPS context is shown.

Enabling Basic Authentication

To enable Basic Authentication you need to provide an authenticator object before starting the management extension. You can find more information in Authenticate Basic Async directive

Scala

copysourcedef myUserPassAuthenticator(credentials: Credentials): Future[Option[String]] =
  credentials match {
    case p @ Credentials.Provided(id) =>
      Future {
        // potentially
        if (p.verify("p4ssw0rd")) Some(id)
        else None
      }
    case _ => Future.successful(None)
  }
// ...
val management = AkkaManagement(system)
management.start(_.withAuth(myUserPassAuthenticator))

Java

copysourcefinal Function<Optional<SecurityDirectives.ProvidedCredentials>, CompletionStage<Optional<String>>>
  myUserPassAuthenticator = opt -> {
  if (opt.filter(c -> (c != null) && c.verify("p4ssw0rd")).isPresent()) {
    return CompletableFuture.completedFuture(Optional.of(opt.get().identifier()));
  } else {
    return CompletableFuture.completedFuture(Optional.empty());
  }
};
// ...
management.start(settings -> settings.withAuth(myUserPassAuthenticator));

You can combine the two security options in order to enable HTTPS as well as basic authentication. In order to do this, invoke start(transformSettings) where transformSettings is a function to amend the ManagementRouteProviderSettings. Use .withAuth and .withHttpsConnectionContext if the ManagementRouteProviderSettings to enable authentication and HTTPS respectively.

Stopping Akka Management

In a dynamic environment you might stop instances of Akka Management, for example if you want to free up resources taken by the HTTP server serving the Management routes.

You can do so by calling stop() on AkkaManagement. This method return a Future[Done] to inform when the server has been stopped.

Scala

copysourceval management = AkkaManagement(system)
management.start()
//...
val bindingFuture = management.stop()
bindingFuture.onComplete { _ =>
  println("It's stopped")
}

Java

copysourceval management = AkkaManagement(system)
management.start()
//...
val bindingFuture = management.stop()
bindingFuture.onComplete { _ =>
  println("It's stopped")
}

Developing Extensions

This project provides a set of management extensions. To write third-party extensions to Akka Management, here are few pointers about how it all works together.

The akka-management module provides the central HTTP endpoint to which extensions can register themselves.

An extension can contribute to the exposed HTTP routes by defining named route providers in the akka.management.http.routes configuration section in its own reference.conf. The core AkkaManagement extension collects all the routes and serves them together under the Management HTTP server. This enables easy extension of management capabilities (such as health-checks or cluster information etc) without the boilerplate and overhead to start separate HTTP servers for each extension.

For example, the “Cluster HTTP Management” module exposes HTTP routes that can be used to monitor, and even trigger joining/leaving/downing decisions via HTTP calls to these routes. The routes and logic for these are implemented inside the akka-management-cluster-http.

Management route providers should be regular extensions that additionally extend the akka.management.scaladsl.ManagementRouteProvider or akka.management.javadsl.ManagementRouteProvider interface.

Libraries may register routes into the management routes by defining entries to this setting the library reference.conf:

akka.management.http.routes {
  name = "FQCN"
}

Where the name of the entry should be unique to allow different route providers to be registered by different libraries and applications.

The FQCN is the fully qualified class name of the ManagementRouteProvider.

Route providers included by a library (from reference.conf) can be excluded by an application by using "" or null as the FQCN of the named entry, for example:

akka.management.http.routes {
  cluster-management = ""
}

As a best practice, Management extensions that do something proactively should not be started automatically, but rather manually by the user. One example of that is Cluster Bootstrap. It contributes routes to Akka Management, but the bootstrapping process does not start unless ClusterBootstrap().start() is invoked. Thus, the user can decide when exactly the application is ready to start joining an existing cluster. When cluster bootstrap is autostarted through configuration there is no control over this and the extension is started with the actor system.