Tutorial: Injecting Environments

Flyway Teams

This brief tutorial will teach you how to inject environments for your migrations to execute against.

Introduction

When working with databases you often have different environments such as development, test or production. In each of these environments you might want to execute different migrations, and this can be achieved with a placeholder and the shouldExecute script configuration parameter.

shouldExecute is a parameter that lets you easily customize when a migration should execute by providing it a boolean expression. Unlike skipExecutingMigrations, this will not update the schema history table. It also supports placeholders within its boolean expressions, which gives you the flexibility to customize the execution of migrations as needed.

If you aren't already familiar with the concept of script configuration parameters, you can read about it here. If you'd like to brush up on your knowledge of placeholders, you can read about them here.

Example

Let's say we have the following migrations:

V1__dev_migration_1.sql
V2__tst_migration_1.sql
V3__prd_migration_1.sql

V1 should only be executed in the development environment, V2 in the test environment and V3 in the production environment.

Migration V1's script configuration file V1__dev_migration_1.sql.conf will need the line shouldExecute=${environment}==development.
Migration V2's script configuration file V2__tst_migration_1.sql.conf will need the line shouldExecute=${environment}==test.
Migration V3's script configuration file V3__prd_migration_1.sql.conf will need the line shouldExecute=${environment}==production.

If we set the value of the ${environment} placeholder to contain the environment we are running Flyway in, we can achieve our desired result.

Running:

flyway -placeholders.environment=development migrate

Will only apply V1. Similarly, running:

flyway -placeholders.environment=test migrate

Will only apply V2 and running:

flyway -placeholders.environment=production migrate

Will only apply V3.

Summary

In this brief tutorial we saw how to:

• Use shouldExecute to control which environments our migrations execute in