Lagom 1.3.2 is released!

The Lagom team has just released Lagom 1.3.2. This release includes bug fixes and other minor changes, a dependency management improvement for Maven users, and deprecates a feature that proved to be confusing.

Updating

To update an sbt project, change the version of lagom-sbt-plugin in your project/plugins.sbt file.

To update a Maven project, change the lagom.version property in your top-level pom.xml.

If you are using Lagom’s support for Maven builds or Cassandra persistence, there are some other (optional) steps you should follow below.

Dependency management in Maven

Lagom brings together several rich libraries and frameworks and this means many transitive dependencies. Managing these dependencies and avoiding conflicts can be tricky.

Lagom 1.3.2 introduces a new POM artifact that you can use in your top-level pom.xml in order to control the versions of transitive dependencies brought in by both Lagom and other libraries you depend on. This relies on Maven’s support for importing dependencies in the dependencyManagement section of your POM.

To use this, follow these steps:

1. Open the top-level pom.xml for each of your Maven Lagom projects in an editor
2. Add an import-scope dependency for lagom-maven-dependencies to the dependencyManagement section, within the nested dependencies element:

   <dependency>
       <groupId>com.lightbend.lagom</groupId>
       <artifactId>lagom-maven-dependencies</artifactId>
       <version>${lagom.version}</version>
       <scope>import</scope>
       <type>pom</type>
   </dependency>
   

3. Remove any other previous entries for dependencies with the com.lightbend.lagom groupId, and the entries for akka-actor_2.11 and akka-stream_2.11.

This ensures that the resolved versions of all artifacts that Lagom depends on, directly or indirectly, match the versions that Lagom was tested with.

New projects built from the Lagom Maven archetype include this configuration by default. You might want to create a new project from the archetype to compare the generated pom.xml with your existing projects.

This dependencyManagement feature of Maven has no exact equivalent in sbt. We have found sbt’s default conflict resolution algorithm to be less surprising than Maven’s, and has fewer problems in practice, but we are looking into possibilities to improve this further in sbt as well.

Deprecated: default Cassandra keyspaces

Lagom’s persistence needs a few tables to store its data. These tables are stored in Cassandra keyspaces. Each service should use a unique keyspace name so that the tables of different services do not conflict with each other. You need to configure the keyspaces that are used for these tables in the application.conf file of each of your service implementation projects. For example:

my-service.cassandra.keyspace = my_service

cassandra-journal.keyspace = ${my-service.cassandra.keyspace}
cassandra-snapshot-store.keyspace = ${my-service.cassandra.keyspace}
lagom.persistence.read-side.cassandra.keyspace = ${my-service.cassandra.keyspace}

Previous versions of Lagom automatically calculated a default Cassandra keyspace for each service, based on the name of the service project, and injected this keyspace configuration in development mode. When running in production, these calculated keyspaces were not used, resulting in multiple services sharing the same keyspaces by default if these properties were not configured in application.conf.

Because of this unexpected inconsistency between the development and production environments, Lagom 1.3.2 deprecates the development environment behavior and prints a warning if these properties are not defined in a service that uses Cassandra persistence. The cassandraKeyspace parameter for the Lagom Maven plugin and lagomCassandraKeyspace setting for the Lagom sbt plugin are also deprecated, as it was not clear to everyone that these settings only affect the development environment, and are not used when keyspaces are configured in application.conf.

New projects built from the Lagom Maven archetype or using sbt new and Lagom’s g8 templates (either java or scala ) include this configuration by default, using the name of the project it prompts you for to assign a default keyspace to the example persistent service implementation. You can change this default as required, and should be sure to configure unique keyspaces for additional service implementations as you create them.

In Lagom 1.4, services that use Cassandra persistence will fail on startup when these properties are not defined.

See Storing Persistent Entities in Cassandra for configuration details and issue #578 for more background.

Change log

See the change log for more details on exactly what has been fixed in each release.

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