40. Cloud Foundry

40. Cloud Foundry
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Cloud Foundry provides default buildpacks that come into play if no other buildpack is specified. The Cloud Foundry Java 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 prompts as follows, substituting the path to your compiled .jar for mine. Be sure to have logged in with your cf command line client before attempting to use it.

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

If there is a Cloud Foundry manifest.yml file present in the same directory, it will be consulted. If not, the client will prompt you with questions it has about how it should deploy and manage your application, starting with its name:

Name> acloudyspringtime

Instances> 1

1: 128M
2: 256M
3: 512M
4: 1G
Memory Limit> 256M

Creating acloudyspringtime... OK

1: acloudyspringtime
2: none
Subdomain> acloudyspringtime

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

Creating route acloudyspringtime.cfapps.io... OK
Binding acloudyspringtime.cfapps.io to acloudyspringtime... OK

Create services for application?> n

Bind other services to application?> n

Save configuration?> y

Saving to manifest.yml... OK

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

At this point cf will start uploading your application:

Uploading acloudyspringtime... OK
Preparing to start acloudyspringtime... OK
-----> Downloaded app package (8.9M)
-----> Java Buildpack source: system
-----> Downloading Open JDK 1.7.0_51 from .../x86_64/openjdk-1.7.0_51.tar.gz (1.8s)
       Expanding Open JDK to .java-buildpack/open_jdk (1.2s)
-----> Downloading Spring Auto Reconfiguration from  0.8.7 .../auto-reconfiguration-0.8.7.jar (0.1s)
-----> Uploading droplet (44M)
Checking status of app acloudyspringtime...
  0 of 1 instances running (1 starting)
  ...
  0 of 1 instances running (1 down)
  ...
  0 of 1 instances running (1 starting)
  ...
  1 of 1 instances running (1 running)
Push successful! App 'acloudyspringtime' available at acloudyspringtime.cfapps.io

Congratulations! The application is now live!

It’s easy to then verify the status of the deployed application:

$ cf apps
Getting applications in ... OK

name                             status    usage      url
...
acloudyspringtime                running   1 x 256M   acloudyspringtime.cfapps.io
...

Once Cloud Foundry acknowledges that your application has been deployed, you should be able to hit the application at the URI given, in this case http://acloudyspringtime.cfapps.io/.

40.1 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!