initial state

Four directories containing Terraform files describing a VPC and an Instance as Null Provider Resources for two environments staging and prod.

• environments/prod/vpc
• environments/prod/ec2-instance
• environments/staging/vpc
• environments/staging/ec2-instance

world with terramate

• rename terramate config to disable production safeguards for this demo
  • cp terramate.tm.hcl.example terramate.tm.hcl
• create stacks by detecting terraform configuration
  • terramate create --all-terraform
  • This will create a stacks.tm.hcl in each directory giving each stack a name and an unique ID (UUID)
• validate stacks are detected by listing them
  • terramate list
• commit the new found configuration for Terramate Stacks
  • git add -A && git commit -m 'feat: initialize Terramate stacks'
• initialize terraform in all stacks an validate the configuration
  • terramate run -- terraform init
  • terramate run -- terraform validate
  • The Terramate configuration in terramate.tm.hcl ensures that we cache the providers in a .tf_plugin_cache_dir by setting the Terraform environment variable TF_PLUGIN_CACHE_DIR. This speeds up terraform init phase as each provider version is downloaded only once.
  • We can ignore the deprecation warning as we use the depricated null data source for demo reasons.
• run a plan in all stacks
  • terramate --log-level info run -- terraform plan
  • log level info enables printing the name of the stack being executed for each stack available
  • Note: Outputs and logging will be improved in one of the next upcoming releases
• apply all stacks to the local state backend
  • terramate --log-level info run -- terraform apply -auto-approve

restructuring

problems

• backend config is code duplication
• providers config is code duplication
• updating providers is annoying and complicated
• the environment needs to be set per stack but could be identified based on hierarchy

solutions:

generate backend

• generate_backend.tm.hcl.example rename to enable backend generation
• run terramate generate to generate gen_backend.tf in each directory
• run terramate run -- rm backend.tf to remove old config

generate providers

• generate_providers.tm.hcl.example rename to enable providers generation
• run terramate generate to generate gen_providers.tf in each directory
• run terramate run -- rm providers.tf to remove old config
• set global tf_provider_null_version_constraint on any level e.g. in stack or per environment in a e.g. /environments/prod/config.tm.hcl file:

  globals {
    tf_provider_null_version_constraint = "3.2.1"
  }

• run terramate generate again to show changes

set and export globals as locals

• export_globals_as_locals.tm.hcl.example rename to enable globals export as locals
• run terramate generate to generate gen_locals.tf
• adjust code to use generated locals instead of hard coded values when calling modules.
• run terramate run -- terraform plan to validate config is still valid and did not change

maintenance

when creating new stacks with the configs enabled, auto generation will always happen and stacks are initialized and ready to go without manually setting up things.