Using Databases and Services

Semaphore offers a virtual machine (VM) based environment, and a containerized Docker environment for running your CI/CD pipelines.

Using databases and background services in VM based environments

In the VM based images, like ubuntu1804, use the [sem-service utility][sem-service] to manage database engines and other services on Semaphore.

Let's say that your CI build needs Redis and PostgreSQL:

# .semaphore/semaphore.yml

version: 1.0

agent:
  machine:
    type: e1-standard-2    # Linux machine type with 2 vCPUs, 4 GB of RAM
    os_image: ubuntu1804   # The Ubuntu 18.04 OS image.

blocks:
  - name: "Test"
    task:
      prologue:
        commands:
          - sem-service start redis
          - sem-service start postgres
      jobs:
        - name: Tests
          commands:
            - createdb -U postgres -h 0.0.0.0 myapp_database
            - echo 'running tests'

Since you have unrestricted access to the job's environment, other options for running services include installing native packages with sudo apt-get install.

Using databases and background services with Docker containers

Semaphore allows you to run your jobs in a Docker environment, where you can start multiple containers. The first container will be used to run your commands, while the rest of the containers will be booted up and linked.

Let's say that your CI build needs Redis and PostgreSQL:

# .semaphore/semaphore.yml

version: v1.0
name: Docker Based Builds

agent:
  machine:
    type: e1-standard-2
    os_image: ubuntu1804

  containers:
    - name: main
      image: semaphoreci/ruby:2.6.1

    - name: db
      image: postgres:9.6
      env_vars:
        - name: POSTGRES_PASSWORD
          value: keyboard-cat

    - name: cache
      image: redis:5.0

blocks:
  - name: "Hello"
    task:
      jobs:
      - name: Hello
        commands:
          # install postgres and redis clients
          - apt-get -y update && apt-get install postgresql-client redis-tools

          # create a database by connecting to 'db' container
          - PGPASSWORD="keyboard-cat" createdb -U postgres -h db -p 5432 -e hello

          # list key in redis container by connecting to the cache container
          - redis-cli -h cache KEYS *

We used the official Postgres and Redis images to start your services.

Using services and test data across blocks

Note that, since all jobs run in isolated environments, the services that you start in one block are not automatically available in other blocks. Likewise, starting a service in one job, doesn't automatically make it available in other jobs of the same block.

To use a service or populate test data in all parallel jobs within a block, specify that in the task prologue. Repeat the same steps in the definition of each block as needed.

Next steps

Almost every project has dependencies, and we can save a lot of time by installing them once and reusing them from a cache. Let's learn how to do that in the next section.

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