Managing buildpack changes

If you notice strange behavior in your application, or if builds / deployments are not working properly and no coding changes were made, one possible cause could be changes to the buildpack used by your application.

Some things to check:

• You can check which buildpack and version your app is using by running cf app APP_NAME
• You can check the latest version of cloud.gov system buildpacks by running: cf buildpacks
• You can check the latest buildpack release version by checking the releases page in the appropriate buildpack GitHub repository: https://github.com/cloudfoundry/{BUILDPACK-TYPE}-buildpack/releases

New buildpack versions are released often to update components and address security vulnerabilities. When a new buildpack is available (either via a reference to a buildpack URL or a system buildpack), it will be picked up and used by your application when you do a cf restage.

Buildpack changes can sometimes cause unexpected behavior because of changes in a runtime, component, or dependency. You should carefully read the release notes for new buildpack releases to ensure that changes don’t adversely impact your application. If you suspect that a buildpack update may be causing issues with your application, you can validate it by using an earlier version of a buildpack to see if a new release includes a breaking change.

To use a specific version of a buildpack, you can do a cf push with the --buildpack or -b option and reference a specific release. For example: cf push APP_NAME -b https://github.com/cloudfoundry/java-buildpack.git#v3.3.0.

It may help to experiment by doing cf push with a prior release to see if this resolves the issue. If it does, you can modify your application to ensure it works properly with the latest buildpack release.