# Share builds across projects

Cross-project builds let you reference a build service from any project in your team or organization. A single build service can produce images consumed by deployment services and jobs across multiple projects.

Use this to organize resources so one build service powers multiple environments. For example, a shared CI build in a `builds` project can deploy to separate `staging`, `qa`, and `production` projects.

## Enable cross-project access

Build services require explicit configuration to allow cross-project references. By default, a build service can only be referenced within its own project.

1. Navigate to your build service.

2. Click **Build options**.

3. Scroll to **Advanced build settings**.

4. Under **Cross project access**, enable **Share build access to other projects**.

5. Select which projects can reference this build service (optional):
  
  
  - By default, all projects in your team can reference this build service
  
  - To restrict access, add specific project IDs to allow only those projects
  
  - Enable **Use as exclusion rule** to allow all projects except the ones listed

6. Click **Update build options**.

Once enabled, the build service can be referenced from deployment services, jobs, and workflows in the allowed projects.

## Reference a shared build

After enabling cross-project access, you can reference the build service from deployment services through the UI or programmatically in templates and workflows.

### Link to a deployment service in the UI

1. Create a new deployment service

2. Under **Deployment**, select **Northflank** as the deployment source

3. The **Link build service** section appears

4. Under **Build service**, select the project and build service you want to deploy

5. Select **Branch** to deploy from

6. Click **Create service**

The deployment service will now use builds from the selected cross-project build service.

### Use in templates and workflows

Cross-project build references work in templates, workflows, and preview blueprints.

Reference a build service using its ID, prefixed with the project ID:

```
<project-id>/<build-service-id>
```

If the build service is in the same project, omit the project ID prefix:

```
<build-service-id>
```

For a deployment service node consuming a cross-project build:

```json
{
  "kind": "DeploymentService",
  "spec": {
    "type": "deployment",
    "internal": {
      "id": "builds-project/shared-build-service",
      "branch": "main",
      "buildSHA": "latest"
    }
  }
}
```

## Access control

Build services can only be referenced by projects in the same team. Access can be controlled on the build service level by allowing access from all or specific projects.

## Next steps

- [Build from a Git repository: Start building from your linked Git repositories in minutes.](/v1/application/build/build-code-from-a-git-repository)
- [Build a repository using a Dockerfile: Configure your application build process using a Dockerfile.](/v1/application/build/build-with-a-dockerfile)
- [Inject secrets: Set build arguments and inject runtime variables into running deployments.](/v1/application/secure/inject-secrets)
- [Upload a secret file: Add secret files that will be mounted in your container.](/v1/application/secure/upload-secret-files)