39. Cloud Foundry

39. Cloud Foundry
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Cloud Foundry provides default buildpacks that come into play if no other buildpack is specified. The Cloud Foundry buildpack has excellent support for Spring applications, including Spring Boot. You can deploy stand-alone executable jar applications, as well as traditional war packaged applications.

Once you’ve built your application (using, for example, mvn clean install) and installed the cf command line tool, simply answer the cf push command’s prompts as follows:

$ cf push --path target/demo-0.0.1-SNAPSHOT.jar

Name> $YOURAPP
Instances> 1
Memory Limit> 256M

Creating $YOURAPP... OK

1: $YOURAPP
2: none
Subdomain> $YOURAPP

1: cfapps.io
2: none
Domain> cfapps.io

Creating route $YOURAPP.cfapps.io... OK
Binding $YOURAPP.cfapps.io to $YOURAPP... OK

Create services for application?> n
Bind other services to application?> n
Save configuration?> y

At this point cf will start uploading your application:

Saving to manifest.yml... OK
Uploading $YOURAPP... OK
Preparing to start $YOURAPP... OK
-----> Downloaded app package (8.7M)
-----> Java Buildpack source: system
-----> Downloading Open JDK 1.7.0_51 from .../openjdk-1.7.0_51.tar.gz (1.4s)
       Expanding Open JDK to .java-buildpack/open_jdk (1.3s)
-----> Downloading Spring Auto Reconfiguration 0.8.7 from .../auto-reconfiguration-0.8.7.jar (0.0s)
-----> Uploading droplet (43M)
Checking status of app $YOURAPP...
 0 of 1 instances running (1 starting)
 0 of 1 instances running (1 starting)
 1 of 1 instances running (1 running)
Push successful! App $YOURAPP available at http://$YOURAPP.cfapps.io

	Note
	Here we are substituting `$YOURAPP` for whatever value you give `cf` when it asks for the `name` of your application.

Once Cloud Foundry acknowledges that your application has been deployed, you should be able to hit the application at the URI provided: http://$YOURAPP.cfapps.io/.

39.1 Binding to services

By default, meta-data about the running application as well as service connection information is exposed to the application as environment variables (for example: $VCAP_SERVICES). This architecture decision is due to Cloud Foundry’s polyglot (any language and platform can be supported as a buildpack) nature; process-scoped environment variables are language agnostic.

Environment variables don’t always make for the easiest API so Spring Boot automatically extracts them and flattens the data into properties that can be accessed through Spring’s Environment abstraction:

@Component
class MyBean implements EnvironmentAware {

    private String instanceId;

    @Override
    public void setEnvironment(Environment environment) {
        this.instanceId = environment.getProperty("vcap.application.instance_id");
    }

    // ...

}

All Cloud Foundry properties are prefixed with vcap. You can use vcap properties to access application information (such as the public URL of the application) and service information (such as database credentials). See VcapApplicationListener Javdoc for complete details.

	Tip
	The Spring Cloud project is a better fit for tasks such as configuring a DataSource; and you can also use Spring Cloud with Heroku too!