How to Deploy Spring on Platform.sh with Redis
Contents:
To activate Redis and then have it accessed by the Spring application already in Platform.sh, it is necessary to modify two files.
Note:
This guide only covers the addition of a service configuration to an existing Spring project already configured to deploy on Platform.sh. Please see the deployment guide for more detailed instructions for setting up app containers and initial projects.
1. Add the Redis service 
In your service configuration, include Persistent Redis with a valid supported version:
data:
type: redis-persistent:6.2
disk: 2562. Add the Redis relationship
In your app configuration, use the service name searchelastic to grant the application access to Elasticsearch via a relationship:
relationships:
redisdata: "data:redis"3. Export connection credentials to the environment
Connection credentials for Redis, like any service, 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 Elasticsearch into it’s own environment variables that can be easily used by Spring. On Platform.sh, custom environment variables can be defined programmatically in a .environment file using jq to do just that:
export SPRING_REDIS_HOST=$(echo $PLATFORM_RELATIONSHIPS | base64 --decode | jq -r ".redisdata[0].host")
export SPRING_REDIS_PORT=$(echo $PLATFORM_RELATIONSHIPS | base64 --decode | jq -r ".redisdata[0].port")
export JAVA_OPTS="-Xmx$(jq .info.limits.memory /run/config.json)m -XX:+ExitOnOutOfMemoryError"
Tip:
Please check the Spring Common Application properties and the Binding from Environment Variables to have access to more credentials options.
4. Connect to Redis
Commit that code and push. The Redis instance is ready to be connected from within the Spring application.