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Stack services

A stack service is a service as included in a stack. It always points to a specific service revision.

It combines the underlying service with stack-level configuration such as:

  • enabled or disabled state
  • selected options and defaults
  • settings, environment variables, and Helm values
  • resources and volumes
  • integrations and links to other stack services
  • configs, tokens, annotations, and cron schedules

Links are defined between stack services, so the stack describes how services work together.

When you create an app instance, each stack service becomes an app service for that deployed copy of the app.

When a later stack revision adds a stack service, upgrading an app instance creates the corresponding app service for that instance. When a later stack revision removes a stack service, upgrading an app instance marks the obsolete app service for deletion and uninstalls its Kubernetes resources after the upgrade.

Stack service machine names must follow the Kubernetes service name rules and be unique within the stack, including derivative stack services.

See Stack configuration for the stack-level controls available for stack services.