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Provision

Having configured the Terraform components, the Atmos components catalog, all the mixins and defaults, and the Atmos parent stacks, we can now provision the components into the stacks.

The vpc-1 Atmos components use the remote state from the vpc-flow-logs-bucket-1 components, therefore the vpc-flow-logs-bucket-1 components must be provisioned first.

Provision Atmos Components into All Stacks​

Provision the vpc-flow-logs-bucket-1 Atmos component into the stacks:

# `core` OU, `dev` account, `us-east-2` and `us-west-2` regions
atmos terraform apply vpc-flow-logs-bucket-1 -s core-ue2-dev
atmos terraform apply vpc-flow-logs-bucket-1 -s core-uw2-dev

# `core` OU, `staging` account, `us-east-2` and `us-west-2` regions
atmos terraform apply vpc-flow-logs-bucket-1 -s core-ue2-staging
atmos terraform apply vpc-flow-logs-bucket-1 -s core-uw2-staging

# `core` OU, `prod` account, `us-east-2` and `us-west-2` regions
atmos terraform apply vpc-flow-logs-bucket-1 -s core-ue2-prod
atmos terraform apply vpc-flow-logs-bucket-1 -s core-uw2-prod

Provision the vpc-1 Atmos component into the stacks:

# `core` OU, `dev` account, `us-east-2` and `us-west-2` regions
atmos terraform apply vpc-1 -s core-ue2-dev
atmos terraform apply vpc-1 -s core-uw2-dev

# `core` OU, `staging` account, `us-east-2` and `us-west-2` regions
atmos terraform apply vpc-1 -s core-ue2-staging
atmos terraform apply vpc-1 -s core-uw2-staging

# `core` OU, `prod` account, `us-east-2` and `us-west-2` regions
atmos terraform apply vpc-1 -s core-ue2-prod
atmos terraform apply vpc-1 -s core-uw2-prod

Stack Search Algorithm​

Looking at the commands above, you might have a question "How does Atmos find the component in the stack and all the variables?"

Let's consider what Atmos does when executing the command atmos terraform apply vpc-1 -s core-ue2-prod:

  • Atmos uses the CLI config stacks.name_pattern: "{tenant}-{environment}-{stage}" to figure out that the first part of the stack name is tenant, the second part is environment, and the third part is stage

  • Atmos searches for the stack configuration file (in the stacks folder and all sub-folders) where tenant: core, environment: ue2 and stage: prod are defined (inline or via imports). During the search, Atmos processes all parent (top-level) config files and compares the context variables specified in the command (-s flag) with the context variables defined in the stack configurations, finally finding the matching stack

  • Atmos finds the component vpc-1 in the stack, processing all the inline configs and all the imports

  • Atmos deep-merges all the catalog imports for the vpc-1 component and then deep-merges all the variables for the component defined in all sections (global vars, terraform vars, base components vars, component vars), producing the final variables for the vpc-1 component in the core-ue2-prod stack

  • And lastly, Atmos writes the final deep-merged variables into a .tfvar file in the component directory and then executes terraform apply -var-file ... command