DB Migration Checker

Overview

DB Migration Checker is a DLE's component that enables integration with CI/CD tools to automatically test migrations in CI/CD pipelines.

Key features

• Automated: DB migration testing in CI/CD pipelines
• Realistic: test results are realistic because real or close-to-real (the same size but no personal data) databases are used, thin-cloned in seconds, and destroyed after testing is done
• Fast and inexpensive: a single machine with a single disk can operate dozens of independent thin clones
• Well-tested DB changes to avoid deployment failures: DB Migration Checker automatically detects (and prevents!) long-lasting dangerous locks that could put your production systems down
• Secure: DB Migration Checker runs all tests in a secure environment: data cannot be copied outside the secure container
• Lots of helpful data points: Collect useful artifacts (such as pg_stat_*** system views) and use them to empower your DB changes review process

How to set up a DB migration checker

• Make sure that the Database Lab Engine is running

• Copy the example configuration file config.example.ci_checker.yml from the Database Lab Engine repository to ~/.dblab/ci_checker/configs/ci_checker.yml:

  mkdir -p ~/.dblab/ci_checker/configs
  
  curl -fsSL https://gitlab.com/postgres-ai/database-lab/-/raw/master/engine/configs/config.example.ci_checker.yml \
    --output ~/.dblab/ci_checker/configs/ci_checker.yml

• Configure the DB migration checker file ci_checker.yml. See the DB Migration Checker configuration reference.

• Launch DB migration checker

  sudo docker run \
    --name dblab_ci_checker \
    --label dblab_control \
    --detach \
    --restart on-failure \
    --publish 2500:2500 \
    --volume /var/run/docker.sock:/var/run/docker.sock \
    --volume /tmp/ci_checker:/tmp/ci_checker \
    --volume ~/.dblab/ci_checker/configs:/home/dblab/configs \
    --env DOCKER_API_VERSION=1.41 \
    postgresai/dblab-ci-checker:3.3.0 

• [optional] Run the localtunnel (or an analog) - use it only for debug purposes to make DB migration instance accessible for a CI pipeline lt --port 2500

• Prepare a new repository with your DB migrations(Flyway, Sqitch, Liquibase, etc.)

  • add secrets:
    • DLMC_CI_ENDPOINT - an endpoint of your Database Lab Migration Checker service. For example, https://ci-checker.example.com/, or in case of debug the endpoint given from the localtunnel.
    • DLMC_VERIFICATION_TOKEN - verification token for the Database Lab Migration Checker API

• Configure a new workflow in the created repository (see an example of configuration)

  • add a custom action: https://github.com/marketplace/actions/database-lab-realistic-db-testing-in-ci
  • provide input params for the action (the full list of available input params)
  • provide environment variables:
    • DLMC_CI_ENDPOINT - use a CI Checker endpoint from the repository secrets
    • DLMC_VERIFICATION_TOKEN - use a verification token from the repository secrets

• Push a commit to the repository

How it works

After configuring all components, the repository is ready to start a CI workflow. Receiving a push event, GitHub starts the workflow with the Database Lab DB migration action. The Database Lab DB migration action makes a request to the DB migration checker. The DB migration checker requests the DLE to create a new clone, start a new container with migration tools and, then runs commands from the GitHub action against this clone.

Take a look at the communication scheme

Available input params

• commands (list, required) - list of commands to run needed database migrations'
• dbname (string, optional, default: "") - database that the workflow is running with
• migration_envs (list, optional) - list of environment variables that will be set during migrations running
• download_artifacts (string, optional, default: "false") - option that allows choosing whether to store artifacts
• observation_interval (string, optional, default: 10) - interval of metric gathering and output (in seconds)
• max_lock_duration (string, optional, default: 10) - maximum allowed duration for locks (in seconds)
• max_duration (string, optional, default: "3600") - maximum allowed duration for observation (in seconds)

Supported DB migration tools:

• Sqitch (Example: https://github.com/agneum/runci)
• Flyway (Example: https://github.com/postgres-ai/dblab-ci-test-flyway)
• Liquibase (Example: https://github.com/postgres-ai/dblab-ci-test-liquibase)
• Ruby on Rails: Active Record Migrations (rake db:migrate)
• Django migrations

There are prepared Docker images with DB migration tools

How to extend

Proposals to extend this list are welcome in the project repository: https://gitlab.com/postgres-ai/custom-images.

tip

If needed, you can specify any custom Docker image with a DB migration tool in the Database Lab Migration Checker configuration. There is one requirement: such an image must remain running during the execution of all commands.

Use these Dockerfiles as examples. You can extend or modify it for your needs.