Tuesday, May 30, 2017

Upgrading Lead Microservice - Use MariaDB and Flyway with Spring Boot



So far I have been using an in-memory H2 database or Mockito for testing the lead microservice. To make the transition towards using the Spring Cloud Config server, I need to upgrade the micro-application to use MariaDB. I will be adding the configuration in the application.yml  the file which in the subsequent post will move over to the config server store. I will also be using Flyway to make it easy to maintain the database schema changes in future. I will use this post to introduce Flyway in the mix. Spring Boot also provides first class integration with Flyway. I am using Flyway as its really quick and easy to get started, minimal learning curve (no DSL) and I am comfortable with it having used it in the past.

Assumptions

  1. MariaDB 10 is installed
  2. Basic familiarity with Flyway
  3. Heidi SQL client is installed.

Step 1 - Update build.gradle to include the MariaDB JDBC and Flyway dependencies.
Do not forget to do a Gradle refresh on your IDE (I am using STS 3.8.4 on Java 8)

Step 2 - Rename the application.properties to application.yml and add the properties shown in listing below.

The lead backend service will run on port 8080. The application now has a name - 'lead-service'. This will be required by the configuration server later. I have also setup the MariaDB data source, the default Tomcat connection pool (recommended in Spring Boot documentation and also I do not want to introduce another dependency on a connection pool like Hikari or BoneCP etc as this pool is very robust). Also, I have added the dialect configuration and default schema name for Hibernate/JPA. Since I want to use the defaults on the database, Flyway will use the test schema and the Flyway managed DDL script will create the schema for the lead backend as 'lead_db'.
Step 3 - Create the DDL scripts for Flyway.
The next step is to create the DDL scripts for Flyway. The scripts should be stored with the lead-backend codebase under src/main/resources/db/migration folder. The file that creates the database schema for the first time is named 'V1.0__init.sql'. Note there are 2 '_', between 'V1.0' and 'init'.

Step 4 - Test
Check the Tomcat console logs to verify that Flyway and JPA worked without any issues.
Figure 1 - Checking the console for Flyway and JPA


Finally, check the DB with HeidiSQL if the Flyway table and 'lead_db' schema tables are created by Flyway.

Figure 2 - HeidiSQL view

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