Collection of git hooks for Terraform to be used with pre-commit framework

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Table of content

• Sponsors
• Table of content
• How to install
  • 1. Install dependencies
  • 2. Install the pre-commit hook globally
  • 3. Add configs and hooks
  • 4. Run
• Available Hooks
• Hooks usage notes and examples
  • checkov
  • infracost_breakdown
  • terraform_docs
  • terraform_docs_replace (deprecated)
  • terraform_fmt
  • terraform_providers_lock
  • terraform_tflint
  • terraform_tfsec
  • terraform_validate
  • terrascan
• Authors
• License

How to install

1. Install dependencies

• pre-commit
• checkov required for checkov hook.
• terraform-docs required for terraform_docs hook.
• terragrunt required for terragrunt_validate hook.
• terrascan required for terrascan hook.
• TFLint required for terraform_tflint hook.
• TFSec required for terraform_tfsec hook.
• infracost required for infracost_breakdown hook.
• jq required for infracost_breakdown hook.

Docker

Pull docker image with all hooks:

TAG=latest
docker pull ghcr.io/antonbabenko/pre-commit-terraform:$TAG

All available tags here.

Build from scratch:

When --build-arg is not specified, the latest version of pre-commit and terraform will be only installed.

git clone git@github.com:antonbabenko/pre-commit-terraform.git
cd pre-commit-terraform
# Install the latest versions of all the tools
docker build -t pre-commit-terraform --build-arg INSTALL_ALL=true .

To install a specific version of individual tools, define it using --build-arg arguments or set it to latest:

docker build -t pre-commit-terraform \
    --build-arg PRE_COMMIT_VERSION=latest \
    --build-arg TERRAFORM_VERSION=latest \
    --build-arg CHECKOV_VERSION=2.0.405 \
    --build-arg INFRACOST_VERSION=latest \
    --build-arg TERRAFORM_DOCS_VERSION=0.15.0 \
    --build-arg TERRAGRUNT_VERSION=latest \
    --build-arg TERRASCAN_VERSION=1.10.0 \
    --build-arg TFLINT_VERSION=0.31.0 \
    --build-arg TFSEC_VERSION=latest \
    .

Set -e PRE_COMMIT_COLOR=never to disable the color output in pre-commit.

MacOS

coreutils is required for terraform_validate hook on MacOS (due to use of realpath).

brew install pre-commit terraform-docs tflint tfsec coreutils checkov terrascan infracost jq

Ubuntu 18.04

sudo apt update
sudo apt install -y unzip software-properties-common
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt install -y python3.7 python3-pip
python3 -m pip install --upgrade pip
pip3 install --no-cache-dir pre-commit
python3.7 -m pip install -U checkov
curl -L "$(curl -s https://api.github.com/repos/terraform-docs/terraform-docs/releases/latest | grep -o -E -m 1 "https://.+?-linux-amd64.tar.gz")" > terraform-docs.tgz && tar -xzf terraform-docs.tgz && rm terraform-docs.tgz && chmod +x terraform-docs && sudo mv terraform-docs /usr/bin/
curl -L "$(curl -s https://api.github.com/repos/terraform-linters/tflint/releases/latest | grep -o -E -m 1 "https://.+?_linux_amd64.zip")" > tflint.zip && unzip tflint.zip && rm tflint.zip && sudo mv tflint /usr/bin/
curl -L "$(curl -s https://api.github.com/repos/aquasecurity/tfsec/releases/latest | grep -o -E -m 1 "https://.+?tfsec-linux-amd64")" > tfsec && chmod +x tfsec && sudo mv tfsec /usr/bin/
curl -L "$(curl -s https://api.github.com/repos/accurics/terrascan/releases/latest | grep -o -E -m 1 "https://.+?_Linux_x86_64.tar.gz")" > terrascan.tar.gz && tar -xzf terrascan.tar.gz terrascan && rm terrascan.tar.gz && sudo mv terrascan /usr/bin/ && terrascan init
sudo apt install -y jq && \
curl -L "$(curl -s https://api.github.com/repos/infracost/infracost/releases/latest | grep -o -E -m 1 "https://.+?-linux-amd64.tar.gz")" > infracost.tgz && tar -xzf infracost.tgz && rm infracost.tgz && sudo mv infracost-linux-amd64 /usr/bin/infracost && infracost register

Ubuntu 20.04

sudo apt update
sudo apt install -y unzip software-properties-common python3 python3-pip
python3 -m pip install --upgrade pip
pip3 install --no-cache-dir pre-commit
pip3 install --no-cache-dir checkov
curl -L "$(curl -s https://api.github.com/repos/terraform-docs/terraform-docs/releases/latest | grep -o -E -m 1 "https://.+?-linux-amd64.tar.gz")" > terraform-docs.tgz && tar -xzf terraform-docs.tgz terraform-docs && rm terraform-docs.tgz && chmod +x terraform-docs && sudo mv terraform-docs /usr/bin/
curl -L "$(curl -s https://api.github.com/repos/accurics/terrascan/releases/latest | grep -o -E -m 1 "https://.+?_Linux_x86_64.tar.gz")" > terrascan.tar.gz && tar -xzf terrascan.tar.gz terrascan && rm terrascan.tar.gz && sudo mv terrascan /usr/bin/ && terrascan init
curl -L "$(curl -s https://api.github.com/repos/terraform-linters/tflint/releases/latest | grep -o -E -m 1 "https://.+?_linux_amd64.zip")" > tflint.zip && unzip tflint.zip && rm tflint.zip && sudo mv tflint /usr/bin/
curl -L "$(curl -s https://api.github.com/repos/aquasecurity/tfsec/releases/latest | grep -o -E -m 1 "https://.+?tfsec-linux-amd64")" > tfsec && chmod +x tfsec && sudo mv tfsec /usr/bin/
sudo apt install -y jq && \
curl -L "$(curl -s https://api.github.com/repos/infracost/infracost/releases/latest | grep -o -E -m 1 "https://.+?-linux-amd64.tar.gz")" > infracost.tgz && tar -xzf infracost.tgz && rm infracost.tgz && sudo mv infracost-linux-amd64 /usr/bin/infracost && infracost register

2. Install the pre-commit hook globally

Note: not needed if you use the Docker image

DIR=~/.git-template
git config --global init.templateDir ${DIR}
pre-commit init-templatedir -t pre-commit ${DIR}

3. Add configs and hooks

Step into the repository you want to have the pre-commit hooks installed and run:

git init
cat <<EOF > .pre-commit-config.yaml
repos:
- repo: https://github.com/antonbabenko/pre-commit-terraform
  rev: <VERSION> # Get the latest from: https://github.com/antonbabenko/pre-commit-terraform/releases
  hooks:
    - id: terraform_fmt
    - id: terraform_docs
EOF

4. Run

Execute this command to run pre-commit on all files in the repository (not only changed files):

pre-commit run -a

Or, using Docker (available tags):

TAG=latest
docker run -v $(pwd):/lint -w /lint ghcr.io/antonbabenko/pre-commit-terraform:$TAG run -a

Execute this command to list the versions of the tools in Docker:

TAG=latest
docker run --entrypoint cat ghcr.io/antonbabenko/pre-commit-terraform:$TAG /usr/bin/tools_versions_info

Available Hooks

There are several pre-commit hooks to keep Terraform configurations (both *.tf and *.tfvars) and Terragrunt configurations (*.hcl) in a good shape:

Hook name	Description	Dependencies Install instructions here
checkov	checkov static analysis of terraform templates to spot potential security issues. Hook notes	checkov Ubuntu deps: python3, python3-pip
infracost_breakdown	Check how much your infra costs with infracost. Hook notes	infracost, jq, Infracost API key
terraform_docs_replace	Runs terraform-docs and pipes the output directly to README.md. DEPRECATED, see #248. Hook notes	python3, terraform-docs
terraform_docs_without_ aggregate_type_defaults	Inserts input and output documentation into README.md without aggregate type defaults. Hook notes same as for terraform_docs	terraform-docs
terraform_docs	Inserts input and output documentation into README.md. Recommended. Hook notes	terraform-docs
terraform_fmt	Reformat all Terraform configuration files to a canonical format. Hook notes	-
terraform_providers_lock	Updates provider signatures in dependency lock files. Hook notes	-
terraform_tflint	Validates all Terraform configuration files with TFLint. Available TFLint rules. Hook notes.	tflint
terraform_tfsec	TFSec static analysis of terraform templates to spot potential security issues. Hook notes	tfsec
terraform_validate	Validates all Terraform configuration files. Hook notes	-
terragrunt_fmt	Reformat all Terragrunt configuration files (*.hcl) to a canonical format.	terragrunt
terragrunt_validate	Validates all Terragrunt configuration files (*.hcl)	terragrunt
terrascan	terrascan Detect compliance and security violations. Hook notes	terrascan

Check the source file to know arguments used for each hook.

Hooks usage notes and examples

checkov

For checkov you need to specify each argument separately:

- id: checkov
  args: [
    "-d", ".",
    "--skip-check", "CKV2_AWS_8",
  ]

infracost_breakdown

infracost_breakdown executes infracost breakdown command and compare the estimated costs with those specified in the hook-config. infracost breakdown normally runs terraform init, terraform plan, and calls Infracost Cloud Pricing API (remote version or self-hosted version).

Unlike most other hooks, this hook triggers once if there are any changed files in the repository.

1. infracost_breakdown supports all infracost breakdown arguments. The following example only shows costs:

   - id: infracost_breakdown
     args:
       - --args=--path=./env/dev
     verbose: true # Always show costs
   

   Output

   Running in "env/dev"
   
   Summary: {
   "unsupportedResourceCounts": {
       "aws_sns_topic_subscription": 1
     }
   }
   
   Total Monthly Cost:        86.83 USD
   Total Monthly Cost (diff): 86.83 USD
   

2. (Optionally) Define cost constrains the hook should evaluate successfully in order to pass:

   - id: infracost_breakdown
     args:
       - --args=--path=./env/dev
       - --hook-config='.totalHourlyCost|tonumber > 0.1'
       - --hook-config='.totalHourlyCost|tonumber > 1'
       - --hook-config='.projects[].diff.totalMonthlyCost|tonumber != 10000'
       - --hook-config='.currency == "USD"'
   

   Output

   Running in "env/dev"
   Passed: .totalHourlyCost|tonumber > 0.1         0.11894520547945205 >  0.1
   Failed: .totalHourlyCost|tonumber > 1           0.11894520547945205 >  1
   Passed: .projects[].diff.totalMonthlyCost|tonumber !=10000              86.83 != 10000
   Passed: .currency == "USD"              "USD" == "USD"
   
   Summary: {
   "unsupportedResourceCounts": {
       "aws_sns_topic_subscription": 1
     }
   }
   
   Total Monthly Cost:        86.83 USD
   Total Monthly Cost (diff): 86.83 USD
   

   • Only one path per one hook (- id: infracost_breakdown) is allowed.
   • Set verbose: true to see cost even when the checks are passed.
   • Hook uses jq to process the cost estimation report returned by infracost breakdown command
   • Expressions defined as --hook-config argument should be in a jq-compatible format (e.g. .totalHourlyCost, .totalMonthlyCost) To study json output produced by infracost, run the command infracost breakdown -p PATH_TO_TF_DIR --format json, and explore it on jqplay.org.
   • Supported comparison operators: <, <=, ==, !=, >=, >.
   • Most useful paths and checks:
     • .totalHourlyCost (same as .projects[].breakdown.totalHourlyCost) - show total hourly infra cost
     • .totalMonthlyCost (same as .projects[].breakdown.totalMonthlyCost) - show total monthly infra cost
     • .projects[].diff.totalHourlyCost - show the difference in hourly cost for the existing infra and tf plan
     • .projects[].diff.totalMonthlyCost - show the difference in monthly cost for the existing infra and tf plan
     • .diffTotalHourlyCost (for Infracost version 0.9.12 or newer) or [.projects[].diff.totalMonthlyCost | select (.!=null) | tonumber] | add (for Infracost older than 0.9.12)
   • To disable hook color output, set PRE_COMMIT_COLOR=never env var.

3. Docker usage. In docker build or docker run command:

   • You need to provide Infracost API key via -e INFRACOST_API_KEY=<your token>. By default, it is saved in ~/.config/infracost/credentials.yml
   • Set -e INFRACOST_SKIP_UPDATE_CHECK=true to skip the Infracost update check if you use this hook as part of your CI/CD pipeline.

terraform_docs

1. terraform_docs and terraform_docs_without_aggregate_type_defaults will insert/update documentation generated by terraform-docs framed by markers:

   <!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
   
   <!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
   

   if they are present in README.md.

2. It is possible to pass additional arguments to shell scripts when using terraform_docs and terraform_docs_without_aggregate_type_defaults.

3. It is possible to automatically:

   • create a documentation file
   • extend existing documentation file by appending markers to the end of the file (see item 1 above)
   • use different filename for the documentation (default is README.md)

   - id: terraform_docs
     args:
       - --hook-config=--path-to-file=README.md        # Valid UNIX path. I.e. ../TFDOC.md or docs/README.md etc.
       - --hook-config=--add-to-existing-file=true     # Boolean. true or false
       - --hook-config=--create-file-if-not-exist=true # Boolean. true or false
   

4. You can provide any configuration available in terraform-docs as an argument to terraform_doc hook, for example:

   - id: terraform_docs
     args:
       - --args=--config=.terraform-docs.yml
   
   

5. If you need some exotic settings, it can be done too. I.e. this one generates HCL files:

   - id: terraform_docs
     args:
       - tfvars hcl --output-file terraform.tfvars.model .
   

terraform_docs_replace (deprecated)

DEPRECATED. Will be merged in terraform_docs. See #248 for details.

terraform_docs_replace replaces the entire README.md rather than doing string replacement between markers. Put your additional documentation at the top of your main.tf for it to be pulled in. The optional --dest argument lets you change the filename that gets created/modified.

Example:

- id: terraform_docs_replace
  args:
    - --sort-by-required
    - --dest=TEST.md

terraform_fmt

1. terraform_fmt supports custom arguments so you can pass supported flags. Eg:

    - id: terraform_fmt
      args:
        - --args=-no-color
        - --args=-diff
        - --args=-write=false
   

terraform_providers_lock

1. The hook requires Terraform 0.14 or later.

2. The hook invokes two operations that can be really slow:

   • terraform init (in case .terraform directory is not initialised)
   • terraform providers lock

   Both operations require downloading data from remote Terraform registries, and not all of that downloaded data or meta-data is currently being cached by Terraform.

3. terraform_providers_lock supports custom arguments:

    - id: terraform_providers_lock
      args:
         - --args=-platform=windows_amd64
         - --args=-platform=darwin_amd64
   

4. It may happen that Terraform working directory (.terraform) already exists but not in the best condition (eg, not initialized modules, wrong version of Terraform, etc.). To solve this problem, you can find and delete all .terraform directories in your repository:

   echo "
   function rm_terraform {
       find . -name ".terraform*" -print0 | xargs -0 rm -r
   }
   " >>~/.bashrc
   
   # Reload shell and use `rm_terraform` command in the repo root
   

   terraform_providers_lock hook will try to reinitialize directories before running the terraform providers lock command.

terraform_tflint

1. terraform_tflint supports custom arguments so you can enable module inspection, deep check mode, etc.

   Example:

   - id: terraform_tflint
     args:
       - --args=--deep
       - --args=--enable-rule=terraform_documented_variables
   

2. When you have multiple directories and want to run tflint in all of them and share a single config file, it is impractical to hard-code the path to the .tflint.hcl file. The solution is to use the __GIT_WORKING_DIR__ placeholder which will be replaced by terraform_tflint hooks with Git working directory (repo root) at run time. For example:

   - id: terraform_tflint
     args:
       - --args=--config=__GIT_WORKING_DIR__/.tflint.hcl
   

terraform_tfsec

1. terraform_tfsec will consume modified files that pre-commit passes to it, so you can perform whitelisting of directories or files to run against via files pre-commit flag

   Example:

   - id: terraform_tfsec
     files: ^prd-infra/
   

   The above will tell pre-commit to pass down files from the prd-infra/ folder only such that the underlying tfsec tool can run against changed files in this directory, ignoring any other folders at the root level

2. To ignore specific warnings, follow the convention from the documentation.

   Example:

   resource "aws_security_group_rule" "my-rule" {
       type = "ingress"
       cidr_blocks = ["0.0.0.0/0"] #tfsec:ignore:AWS006
   }
   

3. terraform_tfsec supports custom arguments, so you can pass supported --no-color or --format (output), -e (exclude checks) flags:

    - id: terraform_tfsec
      args:
        - >
          --args=--format json
          --no-color
          -e aws-s3-enable-bucket-logging,aws-s3-specify-public-access-block
   

4. When you have multiple directories and want to run tfsec in all of them and share a single config file - use the __GIT_WORKING_DIR__ placeholder. It will be replaced by terraform_tfsec hooks with Git working directory (repo root) at run time. For example:

   - id: terraform_tfsec
     args:
       - --args=--config-file=__GIT_WORKING_DIR__/.tfsec.json
   

   Otherwise, will be used files that located in sub-folders:

   - id: terraform_tfsec
     args:
       - --args=--config-file=.tfsec.json
   

terraform_validate

1. terraform_validate supports custom arguments so you can pass supported -no-color or -json flags:

    - id: terraform_validate
      args:
        - --args=-json
        - --args=-no-color
   

2. terraform_validate also supports custom environment variables passed to the pre-commit runtime:

   - id: terraform_validate
     args:
       - --envs=AWS_DEFAULT_REGION="us-west-2"
       - --envs=AWS_ACCESS_KEY_ID="anaccesskey"
       - --envs=AWS_SECRET_ACCESS_KEY="asecretkey"
   

3. terraform_validate also supports passing custom arguments to its terraform init:

   - id: terraform_validate
     args:
       - --init-args=-lockfile=readonly
   

4. It may happen that Terraform working directory (.terraform) already exists but not in the best condition (eg, not initialized modules, wrong version of Terraform, etc.). To solve this problem, you can find and delete all .terraform directories in your repository:

   echo "
   function rm_terraform {
       find . -name ".terraform*" -print0 | xargs -0 rm -r
   }
   " >>~/.bashrc
   
   # Reload shell and use `rm_terraform` command in the repo root
   

   terraform_validate hook will try to reinitialize them before running the terraform validate command.

   Warning: If you use Terraform workspaces, DO NOT use this workaround (details). Wait to force-init option implementation.

terrascan

1. terrascan supports custom arguments so you can pass supported flags like --non-recursive and --policy-type to disable recursive inspection and set the policy type respectively:

   - id: terrascan
     args:
       - --args=--non-recursive # avoids scan errors on subdirectories without Terraform config files
       - --args=--policy-type=azure
   

   See the terrascan run -h command line help for available options.

2. Use the --args=--verbose parameter to see the rule ID in the scaning output. Usuful to skip validations.

3. Use --skip-rules="ruleID1,ruleID2" parameter to skip one or more rules globally while scanning (e.g.: --args=--skip-rules="ruleID1,ruleID2").

4. Use the syntax #ts:skip=RuleID optional_comment inside a resource to skip the rule for that resource.

Authors

This repository is managed by Anton Babenko with help from these awesome contributors:

License

MIT licensed. See LICENSE for full details.