Prebuilds

Prebuilds help optimize the time to start a workspace by executing any defined installation tasks from the .gitpod.yml in an associated repository asynchronously ahead of time. Gitpod will search the last 100 ancestor commits for a successful prebuild to use as a base for a workspace. Prebuilds work similarly to Continuous Integration (CI) systems by responding to an SCM trigger (e.g. a webhook). For Prebuilds, it helps to be familiar with the following Gitpod features:

1. Projects
2. Tasks
3. .gitpod.yml

Prebuild settings

Commit Interval

To balance frequency of prebuilds with repository activity (e.g. number of commits) you can adjust the number of commits that are skipped between prebuilds. The default is 20.

Filtering Prebuilds

A Prebuild filter allows you to configure when a Prebuild should execute. Prebuild filters help to save costs by not running Prebuilds unnecessarily. You can filter prebuilds in your project settings by:

1. Enable (or disable) Prebuilds
2. On every push event for:
   • all branches (the default setting)
   • default branch only (e.g. main)
   • only branches specified (via glob pattern)

Managing Prebuilds

To configure a Prebuild for a repository you must:

1. Add a init or before task in the repository gitpod.yml.
2. Create a corresponding Project for the repository.
3. Enable Prebuilds in the project settings.

Tip: You can test changes to your tasks and .gitpod.yml directly in your workspace by running the gp validate --prebuild command.

Configuring Prebuilds

A prebuild cannot be executed unless you tell Gitpod explicitly which steps in your .gitpod.yml should be ran in the prebuild. You can do this by ensuring you have either an init or before task.

The below example .gitpod.yml shows a repository that will run npm install inside a Prebuild. The command task with npm start is not executed in the Prebuild as it’s assumed to be a long-running process, e.g. running a web server.

Enabling prebuilds

When a Prebuild ran successfully, you will see the following in your workspace output:

Since prebuilds are included in all our metered pay-as-you-go plans, configuring prebuild settings in your project should help with managing prebuild usage.

View prebuilds

You can find a log of past Prebuilds in your Project settings.

1. Go to the /projects page.
2. Select the Project.
3. Navigate to the “Prebuilds” tab to see Prebuild history.

Rerun a Prebuild

Prebuilds can be triggered manually for debugging purposes. To rerun a prebuild:

1. Navigate to your project and select the Prebuilds tab.
2. Select the Prebuild.
3. Select “Rerun Prebuild”.

Prebuild limitations

Adding Prebuilds requires webhook permissions

Enabling Prebuilds requires the user to have SCM permissions to create a webhook.

Only the /workspace directory is persisted from a Prebuild

Once a Prebuild is completed, a snapshot of the filesystem is taken. However, this snapshot only includes the /workspace directory. Other directories like the home directory are not saved by Prebuilds. To ensure the necessary files are saved, copy them to the /workspace directory before the Prebuild completes, and/or restore those files in your command task.

Prebuilds have a 1 hour time limit

Prebuilds have a timeout of 1 hour. If your before and init tasks combined exceed 1 hour, your Prebuild will be terminated.

Prebuilds are executed as the user who enables them

To pull git information into a workspace, Prebuilds are executed on behalf of the user who created the Prebuild.

Prebuilds are only available to organization members

Even if your repository is public, only members of your Gitpod organization will have access to prebuilds. Public contributors to your repository will not be able to use prebuilds at this time.

Frequently Asked Questions (FAQs)

Can I use project environment variables in Prebuilds?

Environment variables that are defined in project settings will be visible in Prebuilds.