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Final Notes

Atmos provides unlimited flexibility in defining and configuring stacks and components in the stacks.

  • Terraform components can be in different sub-folders in the components/terraform directory. The sub-folders can be organized by type, by teams that are responsible for the components, by operations that are performed on the components, or by any other category

  • Atmos stack manifests can have arbitrary names and can be located in any sub-folder in the stacks directory. Atmos stack filesystem layout is for people to better organize the stacks and make the configurations DRY. Atmos (the CLI) does not care about the filesystem layout, all it cares about is how to find the stacks and the components in the stacks by using the context variables namespace, tenant, environment and stage

  • An Atmos component can have any name that can be different from the Terraform component name. For example, two different Atmos components vpc/1 and vpc/2 can provide configuration for the same Terraform component vpc

  • We can provision more than one instance of the same Terraform component (with the same or different settings) into the same environment by defining many Atmos components that provide configuration for the Terraform component. For example, the following config shows how to define two Atmos components, vpc/1 and vpc/2, which both point to the same Terraform component vpc:

    import:
      - orgs/acme/plat/dev/_defaults
      - mixins/region/us-east-2
      # Import the defaults for all VPC components
      - catalog/vpc/defaults

    components:
      terraform:
        # Atmos component `vpc/1`
        vpc/1:
          metadata:
            # Point to the Terraform component in `components/terraform/vpc`
            component: vpc
            # Inherit the defaults for all VPC components
            inherits:
              - vpc/defaults
          # Define/override variables specific to this `vpc/1` component
          vars:
            name: vpc-1
            ipv4_primary_cidr_block: 10.9.0.0/18

        # Atmos component `vpc/2`
        vpc/2:
          metadata:
            # Point to the Terraform component in `components/terraform/vpc`
            component: vpc
            # Inherit the defaults for all VPC components
            inherits:
              - vpc/defaults
          # Define/override variables specific to this `vpc/2` component
          vars:
            name: vpc-2
            ipv4_primary_cidr_block: 10.10.0.0/18

    Then we can execute the following atmos commands to provision the two VPCs into the dev account in the us-east-2 region:

    atmos terraform apply vpc/1 -s plat-ue2-dev
    atmos terraform apply vpc/2 --stack plat-ue2-dev

All the above makes Atmos an ideal framework to organize infrastructure, to design for organizational complexity, and to provision multi-account environments for very complex organizations.