suzuki-shunsuke/tfcmt v4.9.0-1

on GitHub

v4.8.0...v4.9.0-1

Features

#1083 #1115 support masking secrets

You can mask secrets in outputs of terraform.
This feature prevents the leak of secrets.

The following outputs are masked.

• Standard output of terraform command
• Standard error output of terraform command
• Pull request comment of tfcmt plan and tfcmt apply
• local files created by --output option

You can use environment variables TFCMT_MASKS and TFCMT_MASKS_SEPARATOR.

• TFCMT_MASKS: A list of masks. Masks are joined by TFCMT_MASKS_SEPARATOR
• TFCMT_MASKS_SEPARATOR: A separator of masks. The default value is ;

The format of each mask is ${type}:${value}.
${type} must be either env or regexp.
If ${type} is env, ${value} is a masked environment variable name.
If ${type} is regexp, ${value} is a masked regular expression.

e.g. Mask GitHub access tokens and the environment variable DATADOG_API_KEY.

export TFCMT_MASKS="env:GITHUB_TOKEN;env:DATADOG_API_KEY;regexp:ghp_[^ ]+"
tfcmt plan -- terraform plan

e.g. Change the separator to /.

export TFCMT_MASKS_SEPARATOR=/
export TFCMT_MASKS="env:GITHUB_TOKEN/env:DATADOG_API_KEY/regexp:ghp_[^ ]+"

All matching strings are replaced with ***.
Replacements are done in order of TFCMT_MASKS, so the result depends on the order of TFCMT_MASKS.
For example, if TFCMT_MASKS is regexp:foo;regexp:foo.*, regexp:foo.* has no meaning because all foo are replaced with *** before replacing foo.* with *** so foo.* doesn't match with anything.

Example

This example creates a resource google_cloudbuild_trigger.
This resource has a GitHub Access token as a field substitutions._GH_TOKEN.

main.tf

resource "google_cloudbuild_trigger" "filename_trigger" {
  location = "us-central1"

  trigger_template {
    branch_name = "main"
    repo_name   = "my-repo"
  }

  substitutions = {
    _GH_TOKEN = var.gh_token # Secret
  }

  filename = "cloudbuild.yaml"
}

variable "gh_token" {
  type        = string
  description = "GitHub Access token"
}

terraform {
  required_providers {
    google = {
      source  = "hashicorp/google"
      version = "5.13.0"
    }
  }
}

If you run terraform plan without masking, the secret would be leaked.
To prevent the leak, let's mask the secret.

export TFCMT_MASKS=env:TF_VAR_gh_token # Mask the environment variable TF_VAR_gh_token

Please see _GH_TOKEN in the output of tfcmt plan and the pull request comment.
You can confirm _GH_TOKEN is masked as *** properly.

$ tfcmt plan -- terraform plan
tfcmt plan -- terraform plan

Terraform used the selected providers to generate the following execution
plan. Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # google_cloudbuild_trigger.filename_trigger will be created
  + resource "google_cloudbuild_trigger" "filename_trigger" {
      + create_time   = (known after apply)
      + filename      = "cloudbuild.yaml"
      + id            = (known after apply)
      + location      = "us-central1"
      + name          = (known after apply)
      + project       = "hello"
      + substitutions = {
          + "_GH_TOKEN" = "***"
        }
      + trigger_id    = (known after apply)

      + trigger_template {
          + branch_name = "main"
          + project_id  = (known after apply)
          + repo_name   = "my-repo"
        }
    }

Plan: 1 to add, 0 to change, 0 to destroy.

─────────────────────────────────────────────────────────────────────────────

Note: You didn't use the -out option to save this plan, so Terraform can't
guarantee to take exactly these actions if you run "terraform apply" now.