Java CF Env Parent

Java CFEnv is a library for easily accessing the environment variables set when deploying an application to Cloud Foundry. It is modeled after the design of the node library node-cfenv and other -cfenv libraries in the Cloud Foundry ecosystem.

The class CfEnv is the entry point to the API for accessing Cloud Foundry environment variables. In a Spring application, you can use the Spring Expression Language to invoke methods on bean of type CfEnv to set properties. CFEnv’s Boot support sets common application properties so that Java objects such as the DataSource or the RabbitConnectionFactory are created using Spring Boot autoconfiguration.

The 1.0 M1 blog provides some additional background information.

You can access the stable release from maven central using the coordinates

If you’re attempting to connect a client app to a Spring Cloud Services or Single Sign-On service instance, you should follow their respective docs.

The entry point is the class CfEnv which parses Cloud Foundry environment variables such as VCAP_SERVICES. The information in VCAP_SERVICES is a JSON string that contains credential information to access bound services, such as a database. For example, here is the value of VCAP_SERVICES for an application bound to the mysql and redis services.

The keys in the JSON are not always identical across services, for example in the above JSON the mysql service has added the key named hostname to the credentials while the redis service has contributed the key named host. Most relational database services do not expose a key named jdbcUrl so the URL needs to be created by extracting individual fields and building up the URL string. Since this is such a common case, the CfEnv library provides support to retrieve the URL string for several databases.

To get access to a specific service’s credentials, the keys tag, name, or label can be specified as a criteria for selecting one of the services in the array.

Using the JSON from the previous section, here are some simple API calls to extract credential information.

Multiple strings can be passed to match against more than one tag. There are additional finder methods to search by name and label and the finder method support passing a regex string for pattern matching.

The classes CfService and CfCredentials are returned from the following API calls and have methods for accessing common fields in addition to a generic get(String) map API.

The class CfVolume contains information for a shared disk provided by Cloud Foundry volume services. You can access it using the getVolumes method on CfService as shown below.

JDBC Support

CfJdbcEnv cfJdbcEnv = new CfJdbcEnv()
CfJdbcService cfJdbcService = cfJdbcEnv.findJdbcService();

String jdbcUrl = cfJdbcService.getJdbcUrl();
String username = cfJdbcService.getUsername();
String password = cfJdbcService.getPassword();
String driverClassName = cfJdbcService.getDriverClassName();

String jdbcUrl1 = cfJdbcEnv.findJdbcServiceByName("mysqlA").getUrl();
String jdbcUrl2 = cfJdbcEnv.findJdbcServiceByName("mysqlB").getUrl();

cf cups sqlserver-ups -p '{ "uri": "sqlserver://hostname:1433;database=test_db", "username": "someuser", "password": "whatmeworry?" }'

cf cups sqlserver-ups -p '{ "jdbcUrl": "jdbc:sqlserver://hostname:1433;database=test_db;user=someuse;password=whatmeworry?" }'

Use with Spring

@Bean
public CfJdbcEnv cfJdbcEnv() {
  return new CfJdbcEnv();
}

myDatasourceUrl=#{ cfJdbcEnv.findJdbcService().getUrl() }

@Bean
public CfEnv cfEnv() {
  return new CfEnv();
}

cassandra.contact-points=#{ cfEnv.findCredentialsByTag('cassandra').get('node_ips') }
cassandra.username=#{ cfEnv.findCredentialsByTag('cassandra').getUserName() }
cassandra.password=#{ cfEnv.findCredentialsByTag('cassandra').getPassword() }
cassandra.port=#{ cfEnv.findCredentialsByTag('cassandra').get('cqlsh_port') }

myapp.config.path=#{ cfEnv.findServiceByName("nfs1").getVolumes().get(0).getPath() }

Using Spring Boot

cfenv.service.{serviceName}.enabled=false

Connecting Multiple Instances of a Single Service Type

Pushing your application to Cloud Foundry

cf set-env <APP> JBP_CONFIG_SPRING_AUTO_RECONFIGURATION '{enabled: false}'

cf set-env <APP> SPRING_PROFILES_ACTIVE cloud

The interface CfEnvProcesor simplifies what you need to write in most cases. The environment post processor, CfEnvPostProcessor delegates to all CfEnvProcessors that are discovered using Spring’s SpringFactoriesLoader. Here is the implementation for MongoDB

1. In the accept method is where you put determine how to identify your service type. The CfService class has several methods to help make this as easy as possible.

2. Copy over necessary values from the CfCredentails object to Spring Boot auto-configuration keys.

3. Create a CfEnvProcessorProperties instance so that logging which is done in CfEnvPostProcessor reflects your specific service.

Remember to add an entry in spring.factories so that your processor can be discovered.

Building

$ ./mvnw clean install