relationships block defines how services are mapped within your application. By default, your application may not talk to any other container within a project. To access another container you must define a relationship to it.
Each relationship has an arbitrary name, although by convention the primary SQL database of an application (if any) is usually
database. That is the name by which the relationship will be known in the
PLATFORM_RELATIONSHIPS environment variable, which will include credentials for accessing the service.
The relationship is specified in the form
service_name:endpoint_name. The “service name” is the name of the service given in
.platform/services.yaml, or the name of another application in the same project (that is, the
name property of the
.platform.app.yaml file for that application).
The “endpoint” is the exposed functionality of the service to use. For most services the endpoint is the same as the service type. On a few services (i.e. MariaDB and Solr) you can define additional explicit endpoints for multiple databases and cores in your
services.yaml file, and you will need to match those endpoints in your relationships. See the Services documentation for a full list of currently supported service types and service endpoints.
In the following example, there is a single MySQL service named
mysqldb offering two databases, a Redis cache service named
rediscache, and an Elasticsearch service named
relationships: database: 'mysqldb:db1' database2: 'mysqldb:db2' cache: 'rediscache:redis' search: 'searchserver:elasticsearch'