An
ApplicationListener that knows where to find VCAP (a.k.a. Cloud Foundry)
meta data in the existing environment. It parses out the VCAP_APPLICATION and
VCAP_SERVICES meta data and dumps it in a form that is easily consumed by
Environment users. If the app is running in Cloud Foundry then both meta data
items are JSON objects encoded in OS environment variables. VCAP_APPLICATION is a
shallow hash with basic information about the application (name, instance id, instance
index, etc.), and VCAP_SERVICES is a hash of lists where the keys are service labels
and the values are lists of hashes of service instance meta data. Examples are:
VCAP_APPLICATION: {"instance_id":"2ce0ac627a6c8e47e936d829a3a47b5b","instance_index":0,
"version":"0138c4a6-2a73-416b-aca0-572c09f7ca53","name":"foo",
"uris":["foo.cfapps.io"], ...}
VCAP_SERVICES: {"rds-mysql-1.0":[{"name":"mysql","label":"rds-mysql-1.0","plan":"10mb",
"credentials":{"name":"d04fb13d27d964c62b267bbba1cffb9da","hostname":"mysql-service-public.clqg2e2w3ecf.us-east-1.rds.amazonaws.com",
"host":"mysql-service-public.clqg2e2w3ecf.us-east-1.rds.amazonaws.com","port":3306,"user":"urpRuqTf8Cpe6",
"username":"urpRuqTf8Cpe6","password":"pxLsGVpsC9A5S"}
}]}
These objects are flattened into properties. The VCAP_APPLICATION object goes straight
to
vcap.application.* in a fairly obvious way, and the VCAP_SERVICES
object is unwrapped so that it is a hash of objects with key equal to the service
instance name (e.g. "mysql" in the example above), and value equal to that instances
properties, and then flattened in the same way. E.g.
vcap.application.instance_id: 2ce0ac627a6c8e47e936d829a3a47b5b
vcap.application.version: 0138c4a6-2a73-416b-aca0-572c09f7ca53
vcap.application.name: foo
vcap.application.uris[0]: foo.cfapps.io
vcap.services.mysql.name: mysql
vcap.services.mysql.label: rds-mysql-1.0
vcap.services.mysql.credentials.name: d04fb13d27d964c62b267bbba1cffb9da
vcap.services.mysql.credentials.port: 3306
vcap.services.mysql.credentials.host: mysql-service-public.clqg2e2w3ecf.us-east-1.rds.amazonaws.com
vcap.services.mysql.credentials.username: urpRuqTf8Cpe6
vcap.services.mysql.credentials.password: pxLsGVpsC9A5S
...
N.B. this initializer is mainly intended for informational use (the application and
instance ids are particularly useful). For service binding you might find that Spring
Cloud is more convenient and more robust against potential changes in Cloud Foundry.