How to Deploy Spring on with JPA

To activate JPA and then have it accessed by the Spring application already configured for, it is necessary to modify two files.

1. Add a SQL database service 

In your service configuration, include a SQL database service with a valid supported version to find a valid version. For PostgreSQL that would look like:

    type: postgresql:14
    disk: 256

2. Grant access to the service through a relationship 

To access the new service, set a relationship in your app configuration.
    postgresdatabase: "dbpostgres:postgresql"

3. Export connection credentials to the environment 

Connection credentials for services are exposed to the application container through the PLATFORM_RELATIONSHIPS environment variable from the deploy hook onward. Since this variable is a base64 encoded JSON object of all of your project’s services, you’ll likely want a clean way to extract the information specific to the database into it’s own environment variables that can be used by Spring. On, custom environment variables can be defined programmatically in a .environment file using jq to do just that:

export DB_PORT=`echo $PLATFORM_RELATIONSHIPS|base64 -d|jq -r ".postgresdatabase[0].port"`
export HOST=`echo $PLATFORM_RELATIONSHIPS|base64 -d|jq -r ".postgresdatabase[0].host"`
export DATABASE=`echo $PLATFORM_RELATIONSHIPS|base64 -d|jq -r ".postgresdatabase[0].path"`
export SPRING_DATASOURCE_URL="jdbc:mysql://${HOST}:${DB_PORT}/${DATABASE}"
export SPRING_DATASOURCE_USERNAME=`echo $PLATFORM_RELATIONSHIPS|base64 -d|jq -r ".postgresdatabase[0].username"`
export SPRING_DATASOURCE_PASSWORD=`echo $PLATFORM_RELATIONSHIPS|base64 -d|jq -r ".postgresdatabase[0].password"`
export JAVA_OPTS="-Xmx$(jq .info.limits.memory /run/config.json)m -XX:+ExitOnOutOfMemoryError"

4. Connect to the service 

Commit that code and push. The specified cluster now always points to the PostgreSQL or any SQL service that you wish.