samwise-CLI: The Open Source Terraform module dependency tracker

Terraform

Terraform is an Infrastructure-as-Code(IaC) tool that is written in Hashicorp Configuration Language(HCL). This article assumes that the reader has worked with Terraform and understand how modules work.

Everyone coding in Terraform has either created their own modules, or at least used someone else's.

Terraform modules

Modules are containers for multiple resources that are used together. A module consists of a collection of .tf and/or .tf.json files kept together in a directory.

Modules are the main way to package and reuse resource configurations with Terraform.

Modules can be published to registries like Terraform registry or GitLab. Modules can also be served from Git repositories by providing the HTTPS or SSH URLs. These can be versioned as well. For example,

module "consul" {
  source = "github.com/hashicorp/example"
}

Versioned:

module "consul" {
  source = "github.com/hashicorp/example?ref=1.2.6"
}

Challenge

As your repositories grow and you reference your modules in other repositories, you would reasonably version your modules to ensure that upstream changes in the source doesn't break your infrastructure. However, it is difficult to keep track of all the new releases for the modules being used and even harder to do it regularly. Unaddressed, this builds overtime as tech debt as one day you discover that a core module is now 3 major versions ahead.

Solution

Presenting samwise-cli, a tool to help track your repository's Terraform/OpenTofu dependencies upstream. Searches your repository for usages of modules and generates a report of the modules that have updates available along with all the versions that are more advanced than the version used currently.

At the moment, there's only one command, but hopefully there'll be more soon as the tool develops.

Darth-Tech / samwise-cli

A CLI application to accompany on your terraform module journey and sharing your burden of module dependency updates, just as one brave Hobbit helped Frodo carry his :)

samwise

A CLI application to accompany on your terraform module journey and sharing your burden of module dependency updates, just as one brave Hobbit helped Frodo carry his :)

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View on GitHub

checkForUpdates

For this to run where modules are using private GitHub repositories, .samwise.yaml config file needs to passed as an argument or needs to be present at the user's home directory.

.samwise.yaml format:

git_key:
git_username:
git_ssh_key_path:

or as environment variables:

SAMWISE_CLI_GIT_KEY
SAMWISE_CLI_GIT_USERNAME
SAMWISE_CLI_GIT_SSH_KEY_PATH

Result

CSV Format

Limitations(or better described as features to be added)

• SSH authentication for retrieving module sources(support added)
• Tracking Hashicorp's registry's module(they have an API to list versions here)
• Auto-creation of PRs with the updates(added experimentally with only committing support, no push and PR yet)

Context for the name

I love Lord of the Rings :)