https://github.com/magnetikonline/terraform-github-action-cache-example

Caching Terraform providers within a GitHub Actions Workflow run to improve execution times.
https://github.com/magnetikonline/terraform-github-action-cache-example

caching github-workflow terraform

Last synced: about 2 months ago
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Caching Terraform providers within a GitHub Actions Workflow run to improve execution times.

• Host: GitHub
• URL: https://github.com/magnetikonline/terraform-github-action-cache-example
• Owner: magnetikonline
• License: mit
• Created: 2021-05-22T12:09:05.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2024-03-22T01:18:54.000Z (9 months ago)
• Last Synced: 2024-03-22T02:31:34.735Z (9 months ago)
• Topics: caching, github-workflow, terraform
• Language: HCL
• Homepage:
• Size: 14.6 KB
• Stars: 39
• Watchers: 6
• Forks: 4
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Terraform GitHub Actions caching example

[![Terraform provider cache example](https://github.com/magnetikonline/terraform-github-action-cache-example/actions/workflows/example.yaml/badge.svg)](https://github.com/magnetikonline/terraform-github-action-cache-example/actions/workflows/example.yaml)

## Summary

An implementation of caching [Terraform providers](https://developer.hashicorp.com/terraform/language/providers) via [`actions/cache`](https://github.com/actions/cache) within a workflow run in an attempt to improve `terraform init|plan|apply` execution times.

Why?

- Providers are external to Terraform itself and require download during `terraform init` operations.

- Common use providers can often be very large in size. For example, the [AWS Provider](https://registry.terraform.io/providers/hashicorp/aws/latest/docs) at time of writing weighs in around `360MB` uncompressed.

- By caching these provider binaries between GitHub Action runs, we hope to have required configuration providers available to `terraform` sooner!

## Example

See: [`.github/workflows/example.yaml`](.github/workflows/example.yaml)

Breakdown of the key workflow steps:

- Git source is fetched and Terraform setup via [`actions/checkout`](https://github.com/actions/checkout) and [`hashicorp/setup-terraform`](https://github.com/hashicorp/setup-terraform) respectively.

- Terraform plugin (provider) cache path is configured:

	- By default Terraform downloads providers to individual `.terraform/` directories alongside a configuration. By enabling a system wide cache, `terraform` downloads each provider _once_ to a central location and symlink back into each `.terraform/` directory - avoiding repeated downloads. [More details here](https://developer.hashicorp.com/terraform/cli/config/config-file#provider-plugin-cache).

	- The plugin cache path is set via the [`TF_PLUGIN_CACHE_DIR`](https://developer.hashicorp.com/terraform/cli/config/environment-variables#tf_plugin_cache_dir) environment variable.

	- With a global plugin cache location enabled, we've now got the perfect candidate for workflow run caching.

- Finally, [`actions/cache`](https://github.com/actions/cache) is setup to save/restore the plugin cache location we've set at `~/.terraform.d/plugin-cache`. The cache key is composed using a hash of dependency lock files (`.terraform.lock.hcl`), introduced in [Terraform 0.14](https://developer.hashicorp.com/terraform/language/files/dependency-lock).

	Configuration lock file can be created/updated via the following:

	```sh

	$ terraform providers lock -platform=darwin_amd64 -platform=darwin_arm64 -platform=linux_amd64

	```

- Finally a `terraform init` is run, which sets up a trivial Terraform configuration of [`main.tf`](main.tf).