Spring Boot + Liquibase (+H2)

I have restarted my Java journey almost an year ago after a few years of complete Javascript. And since then, I have been solely working on creating microservices using Springboot. But the journey doesn't only include Springboot and Java but almost everything surrounding the Cloud Native eco-system.

So, just the same I tried with my Javascript, OracleJET, ADF, Chatbot journeys, I will try to create series of simple blogs to remind myself (and others) about how easy is to code and create something.

What is Liquibase:

Liquibase is a tool to track, version, and deploy database changes. It uses changesets to represent a single change to your database. Each changeset has an “id” and “author” attribute which, along with the directory and file name of the changelog file, uniquely identify it. There are four different ways to define your changes: SQL, XML, YAML, and JSON formats. So you can version control your DB changes easily and depending on your/team's preferred language. Liquibase uses a changelog to explicitly list database changes in order. Not only that, Liquibase tracks which changeSets have or have not been deployed in a tracking table called a DATABASECHANGELOG.

More info : https://www.liquibase.org/get-started

How does changelog look like

In this example I use XML format, but it is pretty much similar for YAML and JSON. (I personally feel, if you are moving to Liquibase you should stop doing SQL for your DB changes.)

Below is an example of create table, quite self-explanatory. A changelog can contain 1 or more changeSet defining the database operation you want to perform.

 

There are several things you can do in changelog/changeset, check out the documentation: https://docs.liquibase.com/concepts/home.html

Spring Boot and Liquibase

Spring Boot provides out-of-the-box support for Liquibase, the only dependency you would need along with some properties (in application properties) is :

<dependency>
   <groupId>org.liquibase</groupId>
   <artifactId>liquibase-core</artifactId>
</dependency>

To create a Spring Boot application with Liquibase as database management

Step 1: Initialize your project

Create a simple project from start.spring.io (I have used JPA, if can alternatively use JDBC as well)

 Once you download and import in your IDE, it would look like this :

 

 Your pom.xml would look like :

 

 

 

Step 2: Add ChangeLogs & changeSets

In this example I have 3 tables and one intersection table.

I have separated the create table and insert data files for better understanding and one master-changelog to define the sequence of execution.

 

 Step 3: Define spring properties

The last step of configuration is defining the spring props for liquibase, h2 database.

 

I have used 2 props for liquibase, there are several others, you can check it here. Above, I had to specify the location of the changelog because it is a xml, for yaml you don't need to.

Running the application

Once you generate the jar and run it, you would see logs of tables getting created and data getting inserted.

 

 

And once started, you check the tables in the h2 console on your browser:

 

 

That's it. The entire code is in Github : https://github.com/sohamda/liquibase-h2

Enjoy!! 

Inpired by

1. https://javadeveloperzone.com/spring-boot/spring-boot-liquibase-example/
2. https://www.baeldung.com/liquibase-refactor-schema-of-java-app
3. https://www.liquibase.org/get-started
4. https://docs.spring.io/spring-boot/docs/current/reference/html/howto.html#howto-database-initialization