travis-migrations

This is the central repository for storing migrations, and executing them against production and development databases on both .org and .com.

Any changes to this document should also be reflected in the Travis Builders Manual

In short, migrations should be run locally while standing in this repository during development. For tests (e.g. via .travis.yml) applications should contain their own tooling that loads the schema (e.g. see travis-hub).

Please use Postgresql 9.6.8 for local development and testing, but note that production and enterprise environments require compatibility with both 9.3 and 9.6.

Installing

git clone https://github.com/travis-ci/travis-migrations.git

Adding migrations

To add a migration, run the gen_migration rake task. For example:

bundle exec rake gen_migration["add_column_x_to_table_y"]

This creates a new ActiveRecord migration file in db/main/migrate, with the current timestamp and the name add_column_x_to_table_y:

create  db/main/migrate/20181007154333_add_column_x_to_table_y.rb

See this guide for creating standalone migrations.

Please make sure your migrations are production safe as per this guide: Safe Operations For High Volume PostgreSQL.

You can run script/dump-schema-docker.sh to generate the schema file using a consistent version of postgres (running in a docker container).

Using Docker to run on PostgreSQL 9.6

We use PostgreSQL 9.6 on production, which is often different than the database installed on many operating systems by default. In order to make it easier to run against 9.6 you can use Docker with a supplied docker-compose.yml file.

Run docker-compose up to start the container. Then you can either change settings in config/database.yml to use postgres as a user, postgres as a password and 5432 as a port, or run with DATABASE_URL specified explicitly, for example:

DATABASE_URL=postgres://postgres:postgres@localhost:5432/travis_test bundle exec rake db:migrate

Running migrations locally

PLEASE NOTE: the DATABASE_URL is the url of the local database that will be created or have migrations run on it. This is configured in the config/database.yml. To specify an environment append RAILS_ENV= to each bash command, eg to create the test database use:

RAILS_ENV=test bundle exec rake db:create

To setup the database from scratch:

bundle exec rake db:create

To run migrations after the database has been set up:

bundle exec rake db:migrate

When getting ActiveRecord::NoEnvironmentInSchemaError error

Since version 5.0 ActiveRecord will complain if the env info is not saved in the database with an error:

ActiveRecord::NoEnvironmentInSchemaError:

Environment data not found in the schema. To resolve this issue, run:

bin/rails db:environment:set RAILS_ENV=test

The command that it outputs will not work, because we don't install rails scripts. You can run this instead:

bundle exec rake db:environment:set RAILS_ENV=test

You may need to change RAILS_ENV=test to whatever environment you're trying to migrate.

Deploy latest migrations

travis-migrations is deployed to our database apps, and migrations are run from these apps.

Deployments are done using Slack. Replace <env> with the environment of database you want to run migrations on (e.g. org-staging, com-production).

.deploy migrations to <env>

To run migrations, from your terminal use heroku run. Replace with the name of the migrations app for the database you want to run migrations on (e.g. travis-migrations-staging):

heroku run bundle exec rake db:migrate -a <app>

To run a single migration, replace with the timestamp of the migration you want to run if required:

PLEASE NOTE: running this command without :up included will result in migrations after the timestamp being reverted

heroku run bundle exec rake db:migrate:up VERSION=<timestamp> -a <app>

If you are on a branch and want to push that to staging, ensure the branch has been pushed to GitHub then:

.deploy migrations/<branch-name> to <env>

If your push is rejected because the tip of your branch is behind the remote counterpart, append !

.deploy! migrations/<branch-name> to <env>