How to configure different data sources for local testing and deployment in Spring Boot Application

Question

I am trying to find the best way to configure my Spring Boot Web application to easily switching between the following data sources for both local testing and deployment.

1. H2 in memory db. Local testing only.
2. Dev oracle. Local testing and deployment.
3. Prod oracle. Deployment only.

By local testing, I mean to test in IDE environment (Eclipse). Dev and prod oracle databases are set up on two remote servers.

After some research, there are different ways to switch from one data source to another.

1. Use Spring profile. Using H2 and Oracle with Spring Boot. Set up the following files in classpath, application.properties, application-h2. properties and application-dev.properties. While connections for h2 and dev are defined in corresponding properties files, spring.profiles.active is set in application.properties. My understanding is this property can be overridden during build process by specifying spring.profiles.active. However, it seems to be a JVM variable, how do I set it running maven?
2. Maven profile. Create multiple profiles in pom and a filter pointing to application properties files. The profile specified by -P option during maven build will determine which application properties file to look. However, according to maven application with multi environment configuration can't deploy on tomcat, this will generate multiple wars for different deployment. So method 1 is preferred. Plus, it does not apply to switching datasources while testing locally.
3. Persistence units. Define different persistence units for different data sources in persistence.xml. Use EntityManager by choosing a specific unit. Variation of this method include having a variable in unit names which is determined in application.properties.
4. JNDI lookup. Set up a jndi name in application.properties with spring.datasource.jndi-name. The actual database information including url and credentials will be specified in context.xml in the tomcat folder where the war will be deployed.

My mind is set on local testing environment. Gonna go with method 1. Switching between H2 in memory and oracle is so easy just by changing the property in application.properties. Since the testing is usually done in IDE, war does not need to be generated, although answers are welcome for run maven install with spring.profiles.active.

As far as deployment, JNDI is definitely the way to go. However, I am concerned that the two properties in application.properties: spring.profiles.active and spring.datasource.jndi-name may be conflicting with each other. If I have spring.profiles.active=h2 and then tried to deploy the war to prod server, does it try to connect to h2 based on the spring profile or to prod db based on jdni-name? What is the best practice to accommodate all scenarios with enough flexibility?

Also is a explicit configuration class for DataSource required such as Configure Mutiple DataSource in Spring Boot with JNDI? My understanding is application.properties and spring profile should be enough to handle it, right?

Answer 1

• Definitely use Spring profiles.
• You don't want to use Maven profiles as it creates different artifacts. Ask your QA/Release engineers how they feel about having different artifacts for different environments :). They wouldn't be happy.
• H2 is what you want to use in CI server integration testing as well. Such integration testing is fast and easy.
• Instead of changing profile in application.properties, consider defining profile via command line parameter. So that configuration file changes are not required to run your application in different profiles.