Terraform State

1.

• Snapshot of infrastructure
• In file the default file terraform.tfstate
  • json format
• Can be stored in Terraform Cloud
• Inspection and Modification
  • Shouldnt be modified
  • state remove, forget?
• Format:
  • can use with terraform output -json
  • can use with terraform show -json
• All subcommands that modify state (except show, list) will write backup file
  • terraform.tfstate.backup

2. Purpose:

• To map real world resources
  • To guarantee one-to-one mapping
• To track of metadata:
  • like dependencies
• For terraform plan to work faster
• For sharing
• State locking?
• Workspace:
  • Terraform backend?

6. Locking:

• If supported by backend, Terraform will lock states for all operations that could write state
  • happens automatically on all operations that could write state
• terraform force-unlock

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Synopsis:

• terraform state <subcommand> [options] [args]
  • terraform state list: list resources in the state
  • terraform state pull: pull current remote state and output to stdout
  • terraform state push: update remote state from local state
  • terraform state replace-provider: replace provider in state
  • terraform state rm: remove instances from state
  • terraform state show: show a resource in the state

terraform state mv

• move an item in the state
• Allows to:
  • rename existing resources
  • move a resource/module into a module
• instead of rename a resource or move module then terraform apply, resources will be destroyed and recreated
  • so move just change the ref
• rename:
  • terraform state mv aws_vpn.worker aws_vpn.helper
• resource to module:
  • terraform state mv packet_device.worker module.worker.packet_device.main
• module into module
  • terraform state mv module.app module.parent.module.app
• …