Scala Play Continuous Integration#

This guide shows you how to use Semaphore to set up a continuous integration (CI) pipeline for a Scala Play web application.

Demo project#

Semaphore maintains an example Scala Play project:

In the repository, you will find an annotated Semaphore configuration file: .semaphore/semaphore.yml.

The application uses sbt and Gradle.

Overview of the CI pipeline#

The demo Scala Play CI pipeline performs a build matrix with two parallel jobs, each running on a different version of Java. The build runs sbt and Gradle tasks.

Sample configuration#

The project uses the following configuration. If you're new to Semaphore, we recommend going through the guided tour and linked documentation pages for more information before you try the project.

# .semaphore/semaphore.yml
# Use the latest stable version of Semaphore 2.0 YML syntax:
version: v1.0

# Name of your pipeline. In this example we connect two pipelines with
# a promotion, so it helps to differentiate the job of each.
name: Semaphore example for Scala Play

# An agent defines the environment in which your code runs.
# It is a combination of one of available machine types and operating
# system images. See:
# - https://docs.semaphoreci.com/ci-cd-environment/machine-types/
# - https://docs.semaphoreci.com/ci-cd-environment/ubuntu-20.04-image/
agent:
  machine:
    type: e1-standard-2
    os_image: ubuntu2004

# Blocks define the structure of a pipeline and are executed sequentially.
# Each block has a task that defines one or many parallel jobs. Jobs define
# the commands to execute.
# - https://docs.semaphoreci.com/essentials/concepts/
blocks:
  - name: "Scala with Play"
    task:
      env_vars:
        # Define an environment variable
        # Needed for use in scripts/test-sbt and scripts/test-gradle
        # - https://docs.semaphoreci.com/essentials/environment-variables/
        - name: SCALA_VERSION
          value: "2.12.6"
      # Commands in a prologue run at the beginning of each parallel job.
      # - https://docs.semaphoreci.com/reference/pipeline-yaml-reference/
      prologue:
        commands:
          - cd $HOME
          - ls -lah
          # Checkout code from Git repository. This step is mandatory if the
          # job is to work with your code.
          - checkout
          # sem-version expects binary version:
          - sem-version scala 2.12
          # Restore dependencies from the cache, command won't fail if key is
          # missing. More on caching:
          # - https://docs.semaphoreci.com/reference/toolbox-reference/#cache
          - cache restore sbt-$SEMAPHORE_GIT_BRANCH-$(checksum $SEMAPHORE_PROJECT_NAME/build.sbt),sbt-$SEMAPHORE_GIT_BRANCH,sbt-master
          - cache restore ivy2-$SEMAPHORE_GIT_BRANCH-$(checksum $SEMAPHORE_PROJECT_NAME/build.sbt),ivy2-$SEMAPHORE_GIT_BRANCH,ivy2-master
          - cache restore gradle-$SEMAPHORE_GIT_BRANCH-$(checksum $SEMAPHORE_PROJECT_NAME/build.sbt),gradle-$SEMAPHORE_GIT_BRANCH,gradle-master
      jobs:
        - name: Tests
          # Define variables for a build matrix
          # - https://docs.semaphoreci.com/reference/pipeline-yaml-reference/#matrix
          matrix:
            - env_var: JAVA_VERSION
              values: ["8", "11"]
          commands:
            - sem-version java $JAVA_VERSION
            - ./scripts/test-sbt
            - ./scripts/test-gradle
      # Commands in an epilogue run at the end of each parallel job.
      epilogue:
        commands:
        - cd $HOME
        - ls -lah
        - cache store sbt-$SEMAPHORE_GIT_BRANCH-$(checksum $SEMAPHORE_PROJECT_NAME/build.sbt) .sbt
        - cache store ivy2-$SEMAPHORE_GIT_BRANCH-$(checksum $SEMAPHORE_PROJECT_NAME/build.sbt) .ivy2/cache
        - cache store gradle-$SEMAPHORE_GIT_BRANCH-$(checksum $SEMAPHORE_PROJECT_NAME/build.sbt) .gradle/caches

Run the demo Play project yourself#

A good way to start using Semaphore is to take a demo project and run it yourself. Here’s how to build the demo project with your own account:

  1. Fork the project on GitHub to your own account.
  2. Clone the repository to your local machine.
  3. In Semaphore, follow the link in the sidebar to create a new project.
  4. Create a secret as per instructions above.
  5. Edit any file and push to GitHub, and Semaphore will run the CI/CD pipeline.

Next steps#

Congratulations! You have set up your first Scala continuous integration project on Semaphore. Next, you will probably want to configure deployment. For more information and practical examples, see: