Configure Dependencies Between Components

Atmos supports configuring the relationships between components in the same or different stacks. You can define dependencies between components to ensure that components are deployed in the correct order.

Before deploying components, it's important to consider the dependencies between components. For example, a database component might depend on a network component. When this happens, it's important to ensure that the network component is deployed before the database component.

Support for Dependencies

Support for dependencies is reliant on the integration used and not all integrations support dependencies.

For example, GitHub Actions do not support dependency order applies, while Spacelift does.

You can define component dependencies by using the settings.depends_on section. The section used to define all the Atmos components (in the same or different stacks) that the current component depends on.

The settings.depends_on section is a map of objects. The map keys are just the descriptions of dependencies and can be strings or numbers. Provide meaningful descriptions or numbering so that people can understand what the dependencies are about.

Why is settings.depends_on a map instead of a list?

We originally implemented settings.depends_on as a list. However, since it’s not clear how lists should be deep-merged, so we decided to convert it to a map instead. In this map, the keys are lexicographically ordered, and based on that order, the dependencies are managed.

Each object in the settings.depends_on section has the following schema:

• component (required) - an Atmos component that the current component depends on
• namespace (optional) - the namespace where the Atmos component is provisioned
• tenant (optional) - the tenant where the Atmos component is provisioned
• environment (optional) - the environment where the Atmos component is provisioned
• stage (optional) - the stage where the Atmos component is provisioned

The component attribute is required. The rest are the context variables and are used to define Atmos stacks other than the current stack. For example, you can specify:

• namespace if the component is from a different Organization
• tenant if the component is from a different Organizational Unit
• environment if the component is from a different region
• stage if the component is from a different account
• tenant, environment and stage if the component is from a different Atmos stack (e.g. tenant1-ue2-dev)

In the following example, we specify that the top-level-component1 component depends on the following:

• The test/test-component-override component in the same Atmos stack
• The test/test-component component in Atmos stacks in the dev stage
• The my-component component from the tenant1-ue2-staging Atmos stack

components:
  terraform:
    top-level-component1:
      settings:
        depends_on:
          1:
            # If the `context` (namespace, tenant, environment, stage) is not provided,
            # the `component` is from the same Atmos stack as this component
            component: "test/test-component-override"
          2:
            # This component (in any stage) depends on `test/test-component`
            # from the `dev` stage (in any `environment` and any `tenant`)
            component: "test/test-component"
            stage: "dev"
          3:
            # This component depends on `my-component`
            # from the `tenant1-ue2-staging` Atmos stack
            component: "my-component"
            tenant: "tenant1"
            environment: "ue2"
            stage: "staging"
      vars:
        enabled: true

tip

Refer to atmos describe dependents CLI command for more information.