Best practices

expected time	requirements
90 minutes	A computer with Terraform installed, terraform knowledge.

Goal: Use the most common best practices

Explanation

Let’s go over a few best practices. Likey you/your company also has best practices. There is time to discuss these.

HashiCorp has a Terraform Style Guide as well, which covers a lot!

Variables

• Use variables. Define them in variables.tf, assign them in tfvars file, or set them in the environment.
• Set sensitive variables in environment variables.
• Use Terragrunt for environmental differences. (Workspaces can also be used…)

Dependencies

• Pin all used providers and modules in versions.tf.
• When writing modules, keep the dependency chain as flat/short as possible.
• For air-gapped installations, use terraform-bundle or refer to your local SCM.

State

• Save the state remotely.
• Restrict access to state, it contains sensitive information.

General

• Use variables for nearly all values. (In other words, write Terraform code like you are writing a Terraform module.)
• Use CI for modules. (and possibly releases)
• validate and format (fmt) often.
• Terraform updates frequently, read release notes. You can “watch” a repository in github.
• Use modules over resources in your root repository.
• It’s a good idea to treat all repositories like a module. (variables.tf, output.tf, version.tf)

Modules

• Spend a good amount of time on a README.md.
• Suggest to use this order when writing new modules:
  1. README.md - Define the purpose of the module.
  2. variables.tf - Think about what to ask for.
  3. locals.tf - Your place to map “simple” variables to complex variables.””
  4. output.tf - Consider what to expose.
  5. main.tf - The “logic” for the module.
  6. versions.tf - Pin all dependencies.
  7. providers.tf - All provider specific configuration.
  8. examples/* - Try your module yourself.
  9. LICENSE - Yes, likely a pretty open one like Apache-2.0
  10. .gitignore - terraform.tfstate, terraform.tfstate.backup, .terraform

Assignment

• Find as many improvements in this example repository.

Bonus assignment

• Make pull requests for the improvements.

Questions

1. Do you know what to improve on your code now?
2. Do you use other practices worth sharing?

Solution

See here.