Configure a terraform repo to update README.md with `terraform-docs` in a `pre-commit` Git hook

terraform-docs-pre-commit.md

1. Save latest terraform-docs pre-built binary into $PATH from terraform-docs GitHub Releases.

   terraform-docs --version
   # terraform-docs version v0.21.0 ...

2. Configure .terraform-docs.yml to update README.md appropriately. Usually this file would be saved in the root of the repo. If you have a modules directory containing many modules with READMEs to update, you can add the recursive argument. See .terraform-docs.yml options docs.

   # https://terraform-docs.io/user-guide/configuration/
   
   formatter: markdown table
   
   output:
     file: README.md
   
   sections:
     show:
       - requirements
       - resources
       - inputs
       - outputs
   
   sort:
     enabled: true
     by: required
   
   # Recursive config for subdirectories with modules
   # https://terraform-docs.io/user-guide/configuration/recursive/
   #recursive:
   #  enabled: true
   #  path: modules
   #  include-main: true

3. Ensure terraform-docs . or a similar command from the root of the repository updates README.md file(s) as desired.
4. Configure git pre-commit hook in file .git/hooks/pre-commit. Git hooks run from the root of the repository, so specify relative paths from there. See Git hooks docs.

   #!/bin/sh
   # https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks
   
   echo "[Git hook: pre-commit] Updating README.md file(s) with terraform-docs"
   terraform-docs .
   git add README.md
   # Option for recursive module subdirectories
   #git add README.md '**/README.md'

5. Update a variable, output, etc. and see the README.md update on commit:

   $ git commit -am 'Update variables documentation'
   [Git hook: pre-commit] Updating README.md file(s) with terraform-docs
   README.md updated successfully
   [main 8095528] Update variables documentation
    2 files changed, 15 insertions(+), 17 deletions(-)