fleet/docs/Contributing/Migrations.md

Fleet database migrations

• Adding/Updating tables
• Populating the database with default data

Adding/Updating tables

We manage database schemas by a series of migrations defined in go code. We use a customized version of the Goose migrations tool to handle these migrations.

Note: Table migrations should be considered immutable once committed to the Fleet repo. Any changes to an existing table should occur in a new migration executing ALTERs.

Also, note that we don't use the Down part of the migrations anymore (older migrations did implement them). The Down function should just return nil, as we use forward-only migrations.

From the project root, run the following shell command:

make migration name=NameOfMigration

Now edit the generated migration file in server/datastore/mysql/migrations/tables/.

You can then update the database by running the following shell commands:

make fleet
./build/fleet prepare db

Populating the database with default data

Note: This pattern will soon be changing. Please check with @zwass if you think you need to write a data migration.

Populating built-in data is also performed through migrations. All table migrations are performed before any data migrations.

Note: Data migrations can be mutable. If tables are altered in a way that would render a data migration invalid (columns changed/removed), data migrations should be updated to comply with the new schema. Data migrations will not be re-run when they have already been run against a database, but they must be updated to maintain compatibility with a fresh DB.

From the project root, run the following shell command:

make migration name=NameOfMigration

Move the migration file from server/datastore/mysql/migrations/tables/ to server/datastore/mysql/migrations/data/, and change the package tables to package data.

Proceed as for table migrations, editing and running the newly created migration file.