Applications

These guides cover what an application can do once you’ve deployed your first one: its services and configuration, then building and shipping it.

• Configuring services: run several services, with health checks, startup dependencies and resource limits.
• Secrets and variables: give services passwords and API keys, and set values in one place.
• Volumes and files: keep data across deployments, and mount configuration files.
• Running jobs before a rollout: migrate a database before the new version starts.
• Connecting applications: let one application’s services reach another’s over a private network.
• Running commands in a container: run a console or an administration task in a running service.
• Building images from Git: build a service’s image from a repository with a Dockerfile.
• Deploying on push: keep the manifest in Git, and deploy every push.
• Environments and promotion: run staging and production, and promote what staging runs to production.
• Restoring a deployment: return an environment to a deployment it ran before, by hand or when a rollout fails.
• Previews: try a branch, or your uncommitted changes, in a short-lived copy of the application.