Integration Testing with Docker Maven Plugin, PostgreSQL, Flyway (Update)

Recently I have written about how one can create a PostgreSQL Docker image with the Docker Maven Plugin to run integration tests that require a database. While this worked all nice and well during development, the concept has one flaw: the plugin will push the database Docker image to a Docker registry during the deploy phase. I do not want this temporary image to end up there. This is the behavior of the Docker Maven Plugin and I have not found a way to work around this. By “work around this” I mean somehow configure the plugin to ignore this custom PSQL image during the “deploy” phase. Unfortunately, there is only a global <filter> that applies to all the phases of the plugin.

There is a proper solution however, at least for what I was using the database.

If you need to customize your database Docker image more than I do then this will not help you. What I want is the following:

  • Create a separate database
  • Have a dedicated database user with its own password

By default, the standard database is postgres and the user is also postgres. I do not want that. I want my application to use similar settings in integration tests as are used in production.

Instead of creating a custom PostgreSQL image in the plugin -> configuration -> images -> image section that injects a SQL file into the bootstrap process of the PSQL server you can configure the name of the database, the user and its password when the container is launched during the run <goal> in the executions -> execution section. Another important change is in the <name> element. In now holds the name and version of the Docker image to pull and start.

<execution>
    <id>start-postgres</id>
    <phase>pre-integration-test</phase>
    <goals>
        <goal>start</goal>
    </goals>
    <configuration>
        <images>
            <image>
                <alias>it-database</alias>
                <name>postgres:9.4</name>
                <run>
                    <ports>
                        <port>it-database.port:5432</port>
                    </ports>
                    <env>
                        <POSTGRES_USER>docker_db_testing_tests</POSTGRES_USER>
                        <POSTGRES_PASSWORD>docker_db_testing_tests</POSTGRES_PASSWORD>
                        <POSTGRES_DB>docker_db_testing_tests</POSTGRES_DB>
                    </env>
                    <wait>
                        <log>(?s)database system is ready to accept connections.*database system is ready to accept connections</log>
                        <time>20000</time>
                    </wait>
                </run>
            </image>
        </images>
    </configuration>
</execution>

I have created another commit to the repository of the original blog post that has this fix.

Keep in mind that the repository is set up in way that is designed to fail. The db/migrations folder holds two database scripts, the second of which results in an error during mvn verify. Testing database migrations was the driving motive behind this setup. Remove the second migration script and the tests will pass without failure.

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