Lagom 1.5 Migration Guide

§Lagom 1.5 Migration Guide

This guide explains how to migrate from Lagom 1.4 to Lagom 1.5. If you are upgrading from an earlier version, be sure to review previous migration guides.

Lagom 1.5 updates to the latest major versions of Play (2.7), Akka (2.5.22) and Akka HTTP (10.1). We have highlighted the changes that are relevant to most Lagom users, but you may need to change code in your services that uses Play APIs directly. You’ll also need to update any Play services in your Lagom project repositories to be compatible with Play 2.7. Please refer to the Play 2.7 migration guide, Akka 2.5.22 release announcement and the Akka HTTP 10.1.x release announcements for more details. Also, review the list of most important changes since 0.22 on the Alpakka-Kafka connector if you use Kafka from Lagom.

For a detailed list of version upgrades of other libraries Lagom builds on such as for Slick, Kafka and others, refer to the release notes.

§Migrating from Lagom 1.4

To migrate from Lagom 1.4 we recommend first migrating to latest version of Lagom 1.4 before upgrading to Lagom 1.5. Refer to the release notes for details upgrading to latest version of Lagom 1.4.

§Build changes

The version of Lagom can be updated by editing the project/plugins.sbt file, and updating the version of the Lagom sbt plugin. For example:

addSbtPlugin("com.lightbend.lagom" % "lagom-sbt-plugin" % "1.5.1")

We also recommend upgrading to sbt 1.2.8 or later, by updating the sbt.version in project/build.properties.

§Deprecations

§Service Ports

Lagom 1.5 now has support for SSL calls for gRPC integration and a new build setting was introduced to configure the https port for a given service manually.

In sbt, the new setting is called lagomServiceHttpsPort. To keep the names aligned, we are deprecating lagomServicePort in favour of lagomServiceHttpPort.

§Persistence testkit TestUtil

The following:

  • com.lightbend.lagom.scaladsl.persistence.cassandra.testkit.TestUtil (lagom-scaladsl-persistence-cassandra)
  • com.lightbend.lagom.scaladsl.persistence.jdbc.testkit.TestUtil (lagom-scaladsl-persistence-jdbc)
  • com.lightbend.lagom.scaladsl.persistence.testkit.AbstractTestUtil (lagom-scaladsl-persistence)

were never intended for public consumption, and therefore have been marked deprecated in 1.5 for removal in 2.0.0.

§ConductR

ConductR is no longer supported with Lagom 1.5.

We recommend migrating to Kubernetes, DC/OS or another deployment solution before upgrading. If you are using ConductR in production and need assistance migrating to other solutions please contact Lightbend.

See Deployment below.

§Lightbend Orchestration

Lightbend Orchestration is not supported with Lagom 1.5. If you used Lightbend Orchestration for your deployment you will have to migrate to a manual process. This migration may happen on the same commit where you upgrade to Lagom 1.5 or you can upgrade your deployment process on a first step (still using Lagom 1.4.x) and later upgrade to Lagom 1.5.

See Deployment below.

§Deployment

ConductR tooling and Lightbend Orchestration handled all the required pieces to deploy on ConductR and Kubernetes or DC/OS. Lagom 1.5 only supports a manually maintained deployment process.

In particular, ConductR tooling and Lightbend Orchestration handled some or all of the following:

  1. extending the application with: cluster bootstrapping, akka management and health checks
  2. Service Location
  3. setting up and producing docker images
  4. preparing the deployment specs for the target orchestrator
  5. Secrets

§Application extensions

Starting with Lagom 1.5 your application will include Akka management HTTP out of the box with health checks enabled by default. Akka management HTTP is a supporting tool for health checks, cluster bootstrap and a few other new features in Lagom 1.5.

Cluster formation now also supports Cluster Bootstrapping as a new way to form a cluster.

These new defaults may require at least two changes on your codebase. First, if you want to opt-in to cluster bootstrapping you must make sure you don’t set seed-nodes. seed-nodes always takes precedence over any other cluster formation mechanism. Second, if you use Cluster Bootstrapping, you will have to setup a discovery mechanism (see the Lagom Cluster reference guide for more details).

§Service Location

You no longer have a ServiceLocator provided by the tooling libraries so you will have to provide one of your choice. We recommend using the new Akka Discovery Service Locator which is implemented using Akka Service Discovery implementations.

Read Akka Discovery Service Locator for details on how to setup the Akka Service Discovery method.

§Docker images and deployment specs

With the removal of ConductR or Lightbend Orchestration, the docker images and deployment specs will have to be maintained manually. Therefore the recommended migration is to take ownership of the Dockerfile, deployment scripts and orchestration specs.

We have written a comprehensive guide on how to deploy a Lagom application in Kubernetes or OpenShift.

We also found that such maintenance can be made easier by using kustomize.

§Secrets

Lightbend Orchestration supported declaring secrets on build.sbt which user’s code could then read from a file in the pod. Starting from Lagom 1.5 there is no specific support for secrets and the recommendation is to use the default option suggested by each target orchestrator. For example, when deploying to Kubernetes or OpenShift declare the secret as an environment variable on your Deployment and inject the environment variable in your application.conf. For example:

my-database {
  password = "${DB_PASSWORD}"
}

§Service Discovery

When opting in to Akka Cluster Bootstrapping as a mechanism for Cluster formation you will have to setup a Service Discovery method for nodes to locate each other.

§Production Settings

New defaults have been added to the Lagom clustering configuration.

The first default configuration concerns how long a node should try to join an cluster. This is configured by the setting akka.cluster.shutdown-after-unsuccessful-join-seed-nodes. Lagom will default this value to 60 seconds. After that period, the Actor System will shutdown if it fails to join a cluster.

The second important change is the default value for lagom.cluster.exit-jvm-when-system-terminated. This was previously off, but we always recommended it to be on in production environments. As of Lagom 1.5, that setting defaults to on. When enabled, Lagom will exit the JVM when the application leave the cluster or fail to join the cluster. In Dev and Test mode, this setting is automatically set to off.

These two properties together are essential for recovering applications in production environments like Kubernetes. Without them, a Lagom node could reach a zombie state in which it wouldn’t provide any functionality but stay around consuming resources. The desired behavior for a node that is not participating on a cluster is to shut itself down and let the orchestration infrastructure re-start it.

§Upgrading a production system

There are no changes affecting a Production Upgrade. If you are running a Lagom 1.4 cluster you can perform a rolling upgrade, just make sure you are using the latest version on the 1.4.x series and, from that, you migrate to the latest version available of the 1.5.x series.

§Downtime upgrade

If you still haven’t adopted ddata as the cluster sharding mode and your application can tolerate a one time only downtime upgrade, we recommend you to enable ddata. Taking advantage of that downtime we recommend you also enable the serializers for akka.Done, akka.actor.Address and akka.remote.UniqueAddress. Once this upgrade is complete, further downtime is not required. Read all the details of this migration on the 1.4 Migration Guide

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