Deploy With Offline Java Buildpack

This document shows how to use an offline Java Buildpack to deploy your applications.

Cloud Foundry’s Java buildpack uses a number of large dependencies. At the time of writing, ~800 MB of sources are pulled into the builder during the buildpack’s execution. Much of this data is brought in from the internet which is convenient as it keeps the buildpack itself small but introduces a great deal of data transfer.

Java builds can be optimized to reduce outside network ingress and improve performance by hosting your own Java buildpack compiled in an offline mode. In its offline mode, Cloud Foundry’s Java buildpack downloads packages that may be used into the cache when creating the builder. This avoids pulling dependencies from the internet at runtime and makes the builder image self contained.

Before You Begin

You will need a cluster with Kf installed and access to the Kf CLI

Additionally, you will need access to the following software:

• git: Git is required to clone a repository.
• ruby: Ruby is required to create the Java bulidpack.
• bundle: Ruby package manager to install Java buildpack dependencies.

Compile the Java Buildpack in Offline mode

Follow Cloud Foundry’s instructions to compile the Java Buildpack in Offline mode: https://github.com/cloudfoundry/java-buildpack/blob/main/README.md#offline-package.

These instructions will generate a .zip extension file containing the buildpack and its dependencies.

Deploy the Java Buildpack

Self Hosted on Kf (Recommended)

Once you have built the Java Buildpack, you can host it on your Kf cluster using a staticfile buildpack.

1. Create a new directory for your static file Kf app i.e. java-buildpack-staticapp
2. Create a new manifest in that directory manifest.yml with the contents:

---
applications:
  - name: java-buildpack-static

3. Create an emptyfile named Staticfile (case sensitive) in the directory. This indicates that this is a static app to the staticfile buildpack which will create a small image containing the contents of the directory + an nginx installation to host your files.
4. Copy the buildpack you created in the previous step into the directory as java-buildpack-offline-<hash>.zip. Your directory structure at this point should resemble:

/
├── java-buildpack-offline-fe26136c.zip
├── manifest.yml
└── Staticfile

6. Run kf push to deploy your app, this will trigger a build.
7. When the push finishes, run kf apps and take note of the URL your app is running on. You will reference this in the next step.

See internal routing to construct an internal link to your locally hosted buildpack. The URL should resemble <your route>/java-buildpack-offline-<hash>.zip. Take note of this URL as you will reference it later in your application manifests or in your cluster’s buildpack configuration.

Served from Google Cloud Storage

See the Google Cloud documentation on creating public objects in a Cloud Storage bucket: https://cloud.google.com/storage/docs/access-control/making-data-public.

To find the URL where your buildpack is hosted and that you will reference in your manifests, see: https://cloud.google.com/storage/docs/access-public-data.

Using an Offline Buildpack

Whole Cluster

You can apply your buildpack to the whole cluster by updating the cluster’s configuration. See configuring stacks to learn how to register your buildpack URL for an entire cluster.

In App Manifest

To use your offline buildpack in a specific app, update your application manifest to specify the buildpack explicitly i.e.

---
applications:
- name: my-app
  buildpacks:
    - http://<your host>/java-buildpack-offline-<hash>.zip