org.springframework.boot.context.listener

Class VcapApplicationListener

java.lang.Object

org.springframework.boot.context.listener.VcapApplicationListener

All Implemented Interfaces:

EventListener, org.springframework.context.ApplicationListener<SpringApplicationEnvironmentAvailableEvent>, org.springframework.core.Ordered

public class VcapApplicationListener
extends Object
implements org.springframework.context.ApplicationListener<SpringApplicationEnvironmentAvailableEvent>, org.springframework.core.Ordered

An ApplicationContextInitializer 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.

Author:

Dave Syer

Field Summary

Fields inherited from interface org.springframework.core.Ordered

HIGHEST_PRECEDENCE, LOWEST_PRECEDENCE

Constructor Summary

Constructors

Constructor and Description
VcapApplicationListener()

Method Summary

Methods

Modifier and Type	Method and Description
int	getOrder()
void	onApplicationEvent(SpringApplicationEnvironmentAvailableEvent event)
void	setOrder(int order)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

VcapApplicationListener

public VcapApplicationListener()

Method Detail

setOrder

public void setOrder(int order)

getOrder

public int getOrder()

Specified by:

getOrder in interface org.springframework.core.Ordered

onApplicationEvent

public void onApplicationEvent(SpringApplicationEnvironmentAvailableEvent event)

Specified by:

onApplicationEvent in interface org.springframework.context.ApplicationListener<SpringApplicationEnvironmentAvailableEvent>