Overview

  • Provisioners model actions on the local or remote machines
  • Prepare infrastructure for service
  • Should be used as a last resort
    • For actions not directly represented in Terraform
  • Create-time or destroy-time—cannot be used to perform actions on existing resources
    • Resource must be destroyed and recreated

Anti-Patterns

Pass Data into VMs

  • Instead: utilize e.g. user_data for AWS EC2, or metadata for Google Cloud Compute Engine

Running Configuration Management Software

  • e.g. Ansible
  • Instead: build custom images outside of Terraform, e.g. with HashiCorp Packer

Where First-Class Provider Support is Available

  • Also, make provisioner use as temporary workaround—support may eventually be available
    • Raise ticket with provider to support functionality

Usage

  • Built-in provisioners: file, local-exec, remote-exec
  • Placed inside resource blocks, e.g. for compute instances:
resource "aws_instance" "instance" {
  #...
 
  provisioner "local-exec" {
    command = "echo hello ${self.private_ip}"
  }
}
  • Can have multiple per resource
  • Use self to reference parent attributes
  • Defaults:
    • Run on creation-time, not during updates
    • Failure marks resource as tainted
      • Change with on_failurecontinue or fail
  • Destroy-time: when = destroy
    • Can’t run if provisioner removed from config—destroy resource by setting count = 0 first

Graph View