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pre-commit git hooks to take care of Terraform configurations 🇺🇦

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

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Table of content

How to install

1. Install dependencies

  • pre-commit, terraform or opentofu, git, BASH 3.2.57 or newer, Internet connection (on first run), x86_64 or arm64 compatible operation system, Some hardware where this OS will run, Electricity for hardware and internet connection, Some basic physical laws, Hope that it all will work.

  • checkov required for terraform_checkov hook
  • terraform-docs 0.12.0+ required for terraform_docs hook
  • terragrunt required for terragrunt_validate and terragrunt_valid_inputs hooks
  • terrascan required for terrascan hook
  • TFLint required for terraform_tflint hook
  • TFSec required for terraform_tfsec hook
  • Trivy required for terraform_trivy hook
  • infracost required for infracost_breakdown hook
  • jq required for terraform_validate with --retry-once-with-cleanup flag, and for infracost_breakdown hook
  • tfupdate required for tfupdate hook
  • hcledit required for terraform_wrapper_module_for_each hook

1.1 Custom Terraform binaries and OpenTofu support

It is possible to set custom path to terraform binary.
This makes it possible to use OpenTofu binary tofu instead of terraform.

How binary discovery works and how you can redefine it (first matched takes precedence):

  1. Check if per hook configuration --hook-config=--tf-path=<path_to_binary_or_binary_name> is set
  2. Check if PCT_TFPATH=<path_to_binary_or_binary_name> environment variable is set
  3. Check if TERRAGRUNT_TFPATH=<path_to_binary_or_binary_name> environment variable is set
  4. Check if terraform binary can be found in the user's $PATH
  5. Check if tofu binary can be found in the user's $PATH
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:

[!IMPORTANT] To build image you need to have docker buildx enabled as default builder.
Otherwise - provide TARGETOS and TARGETARCH as additional --build-arg's to docker build.

When hooks-related --build-args are not specified, only the latest version of pre-commit and terraform will be installed.

git clone [email protected]: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 OPENTOFU_VERSION=latest \
    --build-arg TERRAFORM_VERSION=1.5.7 \
    --build-arg CHECKOV_VERSION=2.0.405 \
    --build-arg HCLEDIT_VERSION=latest \
    --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 \
    --build-arg TFUPDATE_VERSION=latest \
    --build-arg TRIVY_VERSION=latest \
    .

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

MacOS
brew install pre-commit terraform-docs tflint tfsec trivy checkov terrascan infracost tfupdate minamijoyo/hcledit/hcledit 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/aquasecurity/trivy/releases/latest | grep -o -E -i -m 1 "https://.+?/trivy_.+?_Linux-64bit.tar.gz")" > trivy.tar.gz && tar -xzf trivy.tar.gz trivy && rm trivy.tar.gz && sudo mv trivy /usr/bin
curl -L "$(curl -s https://api.github.com/repos/tenable/terrascan/releases/latest | grep -o -E -m 1 "https://.+?_Linux_x86_64.tar.gz")" > terrascan.tar.gz && tar -xzf terrascan.tar.gz terrascan && rm terrascan.tar.gz && sudo mv terrascan /usr/bin/ && terrascan init
sudo apt install -y jq && \
curl -L "$(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 auth login
curl -L "$(curl -s https://api.github.com/repos/minamijoyo/tfupdate/releases/latest | grep -o -E -m 1 "https://.+?_linux_amd64.tar.gz")" > tfupdate.tar.gz && tar -xzf tfupdate.tar.gz tfupdate && rm tfupdate.tar.gz && sudo mv tfupdate /usr/bin/
curl -L "$(curl -s https://api.github.com/repos/minamijoyo/hcledit/releases/latest | grep -o -E -m 1 "https://.+?_linux_amd64.tar.gz")" > hcledit.tar.gz && tar -xzf hcledit.tar.gz hcledit && rm hcledit.tar.gz && sudo mv hcledit /usr/bin/
Ubuntu 20.04+
sudo apt update
sudo apt install -y unzip software-properties-common python3 python3-pip python-is-python3
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/tenable/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/
curl -L "$(curl -s https://api.github.com/repos/aquasecurity/trivy/releases/latest | grep -o -E -i -m 1 "https://.+?/trivy_.+?_Linux-64bit.tar.gz")" > trivy.tar.gz && tar -xzf trivy.tar.gz trivy && rm trivy.tar.gz && sudo mv trivy /usr/bin
sudo apt install -y jq && \
curl -L "$(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 auth login
curl -L "$(curl -s https://api.github.com/repos/minamijoyo/tfupdate/releases/latest | grep -o -E -m 1 "https://.+?_linux_amd64.tar.gz")" > tfupdate.tar.gz && tar -xzf tfupdate.tar.gz tfupdate && rm tfupdate.tar.gz && sudo mv tfupdate /usr/bin/
curl -L "$(curl -s https://api.github.com/repos/minamijoyo/hcledit/releases/latest | grep -o -E -m 1 "https://.+?_linux_amd64.tar.gz")" > hcledit.tar.gz && tar -xzf hcledit.tar.gz hcledit && rm hcledit.tar.gz && sudo mv hcledit /usr/bin/
Windows 10/11

We highly recommend using WSL/WSL2 with Ubuntu and following the Ubuntu installation guide. Or use Docker.

[!IMPORTANT] We won't be able to help with issues that can't be reproduced in Linux/Mac. So, try to find a working solution and send PR before open an issue.

Otherwise, you can follow this gist:

  1. Install git and gitbash
  2. Install Python 3
  3. Install all prerequisites needed (see above)

Ensure your PATH environment variable looks for bash.exe in C:\Program Files\Git\bin (the one present in C:\Windows\System32\bash.exe does not work with pre-commit.exe)

For checkov, you may need to also set your PYTHONPATH environment variable with the path to your Python modules.
E.g. C:\Users\USERNAME\AppData\Local\Programs\Python\Python39\Lib\site-packages

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):

Tip

This command uses your user id and group id for the docker container to use to access the local files. If the files are owned by another user, update the USERID environment variable. See File Permissions section for more information.

TAG=latest
docker run -e "USERID=$(id -u):$(id -g)" -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 --rm --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 and terraform_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 Inserts input and output documentation into README.md. Recommended. Hook notes terraform-docs
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_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. DEPRECATED, use terraform_trivy. Hook notes tfsec
terraform_trivy Trivy static analysis of terraform templates to spot potential security issues. Hook notes trivy
terraform_validate Validates all Terraform configuration files. Hook notes jq, only for --retry-once-with-cleanup flag
terragrunt_fmt Reformat all Terragrunt configuration files (*.hcl) to a canonical format. terragrunt
terragrunt_validate Validates all Terragrunt configuration files (*.hcl) terragrunt
terragrunt_validate_inputs Validates Terragrunt unused and undefined inputs (*.hcl)
terragrunt_providers_lock Generates .terraform.lock.hcl files using Terragrunt. terragrunt
terraform_wrapper_module_for_each Generates Terraform wrappers with for_each in module. Hook notes hcledit
terrascan terrascan Detect compliance and security violations. Hook notes terrascan
tfupdate tfupdate Update version constraints of Terraform core, providers, and modules. Hook notes tfupdate

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

Hooks usage notes and examples

Known limitations

Terraform operates on a per-dir basis, while pre-commit framework only supports files and files that exist. This means if you only remove the TF-related file without any other changes in the same dir, checks will be skipped. Example and details here.

All hooks: Usage of environment variables in --args

All, except deprecated hooks: checkov, terraform_docs_replace

You can use environment variables for the --args section.

Important

You must use the ${ENV_VAR} definition, $ENV_VAR will not expand.

Config example:

- id: terraform_tflint
  args:
  - --args=--config=${CONFIG_NAME}.${CONFIG_EXT}
  - --args=--module

If for config above set up export CONFIG_NAME=.tflint; export CONFIG_EXT=hcl before pre-commit run, args will be expanded to --config=.tflint.hcl --module.

All hooks: Set env vars inside hook at runtime

All, except deprecated hooks: checkov, terraform_docs_replace

You can specify environment variables that will be passed to the hook at runtime.

Important

Variable values are exported verbatim:

  • No interpolation or expansion are applied
  • The enclosing double quotes are removed if they are provided

Config example:

- id: terraform_validate
  args:
    - --env-vars=AWS_DEFAULT_REGION="us-west-2"
    - --env-vars=AWS_PROFILE="my-aws-cli-profile"

All hooks: Disable color output

All, except deprecated hooks: checkov, terraform_docs_replace

To disable color output for all hooks, set PRE_COMMIT_COLOR=never var. Eg:

PRE_COMMIT_COLOR=never pre-commit run

All hooks: Log levels

In case you need to debug hooks, you can set PCT_LOG=trace.

For example:

PCT_LOG=trace pre-commit run -a

Less verbose log levels will be implemented in #562.

Many hooks: Parallelism

All, except deprecated hooks: checkov, terraform_docs_replace and hooks which can't be paralleled this way: infracost_breakdown, terraform_wrapper_module_for_each.
Also, there's a chance that parallelism have no effect on terragrunt_fmt and terragrunt_validate hooks

By default, parallelism is set to number of logical CPUs - 1.
If you'd like to disable parallelism, set it to 1

- id: terragrunt_validate
  args:
    - --hook-config=--parallelism-limit=1

In the same way you can set it to any positive integer.

If you'd like to set parallelism value relative to number of CPU logical cores - provide valid Bash arithmetic expression and use CPU as a reference to the number of CPU logical cores

- id: terraform_providers_lock
  args:
    - --hook-config=--parallelism-limit=CPU*4

Tip

Info useful for parallelism fine-tunning
Tests below were run on repo with 45 Terraform dirs on laptop with 16 CPUs, SSD and 1Gbit/s network. Laptop was slightly used in the process.

Observed results may vary greatly depending on your repo structure, machine characteristics and their usage.

If during fine-tuning you'll find that your results are very different from provided below and you think that this data could help someone else - feel free to send PR.

Hook Most used resource Comparison of optimization results / Notes
terraform_checkov CPU heavy -
terraform_fmt CPU heavy -
terraform_providers_lock (3 platforms,
--mode=always-regenerate-lockfile)		 Network & Disk heavy defaults (CPU-1) - 3m 39s; CPU*2 - 3m 19s; CPU*4 - 2m 56s
terraform_tflint CPU heavy -
terraform_tfsec CPU heavy -
terraform_trivy CPU moderate defaults (CPU-1) - 32s; CPU*2 - 30s; CPU*4 - 31s
terraform_validate (t validate only) CPU heavy -
terraform_validate (t init + t validate) Network & Disk heavy, CPU moderate defaults (CPU-1) - 1m 30s; CPU*2 - 1m 25s; CPU*4 - 1m 41s
terragrunt_fmt CPU heavy N/A? need more info from TG users
terragrunt_validate CPU heavy N/A? need more info from TG users
terrascan CPU moderate-heavy defaults (CPU-1) - 8s; CPU*2 - 6s
tfupdate Disk/Network? too quick in any settings. More info needed 
args:
  - --hook-config=--parallelism-ci-cpu-cores=N

If you don't see code above in your pre-commit-config.yaml or logs - you don't need it.
--parallelism-ci-cpu-cores used only in edge cases and is ignored in other situations. Check out its usage in hooks/_common.sh

checkov (deprecated) and terraform_checkov

checkov hook is deprecated, please use terraform_checkov.

Note that terraform_checkov runs recursively during -d . usage. That means, for example, if you change .tf file in repo root, all existing .tf files in the repo will be checked.

  1. You can specify custom arguments. E.g.:

    - id: terraform_checkov
  args:
    - --args=--quiet
    - --args=--skip-check CKV2_AWS_8

    Check all available arguments here.

For deprecated hook you need to specify each argument separately:

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

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

    - id: terraform_checkov
  args:
    - --args=--config-file __GIT_WORKING_DIR__/.checkov.yml

infracost_breakdown

infracost_breakdown executes infracost breakdown command and compare the estimated costs with those specified in the hook-config. infracost breakdown parses Terraform HCL code, 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 (run infracost breakdown --help to see them). 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. Note that spaces are not allowed in --args, so you need to split it, like this:

    - id: infracost_breakdown
  args:
    - --args=--path=./env/dev
    - --args=--terraform-var-file="terraform.tfvars"
    - --args=--terraform-var-file="../terraform.tfvars"

  3. (Optionally) Define cost constraints 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)

  4. 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:

    <!-- BEGIN_TF_DOCS -->

<!-- END_TF_DOCS -->

    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)

    • use the same insertion markers as terraform-docs. It's default starting from v1.93.
      To migrate everything to terraform-docs insertion markers, run in repo root:

      sed --version &> /dev/null && SED_CMD=(sed -i) || SED_CMD=(sed -i '')
grep -rl --null 'BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK' . | xargs -0 "${SED_CMD[@]}" -e 's/BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK/BEGIN_TF_DOCS/'
grep -rl --null 'END OF PRE-COMMIT-TERRAFORM DOCS HOOK' . | xargs -0 "${SED_CMD[@]}" -e 's/END OF PRE-COMMIT-TERRAFORM DOCS HOOK/END_TF_DOCS/'
    - 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
    - --hook-config=--use-standard-markers=true     # Boolean. Defaults to true (v1.93+), false (<v1.93). Set to true for compatibility with terraform-docs

  4. If you want to use a terraform-docs config file, you must supply the path to the file, relative to the git repo root path:

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

    Warning
    Avoid use recursive.enabled: true in config file, that can cause unexpected behavior.

  5. You can provide any configuration available in terraform-docs as an argument to terraform_docs hook:

    - id: terraform_docs
  args:
    - --args=--output-mode=replace

  6. 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.

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.

To replicate functionality in terraform_docs hook:

  1. Create .terraform-docs.yml in the repo root with the following content:

    formatter: "markdown"

output:
file: "README.md"
mode: replace
template: |-
    {{/** End of file fixer */}}

  2. Replace terraform_docs_replace hook config in .pre-commit-config.yaml with:

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

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

Note

The hook requires Terraform 0.14 or later.

Note

The hook can invoke terraform providers lock that can be really slow and requires fetching metadata from remote Terraform registries - not all of that metadata is currently being cached by Terraform.

Note

Read this if you used this hook before v1.80.0 | Planned breaking changes in v2.0
We introduced `--mode` flag for this hook. If you'd like to continue using this hook as before, please:
  • Specify --hook-config=--mode=always-regenerate-lockfile in args:
  • Before terraform_providers_lock, add terraform_validate hook with --hook-config=--retry-once-with-cleanup=true
  • Move --tf-init-args= to terraform_validate hook

In the end, you should get config like this:

- id: terraform_validate
  args:
    - --hook-config=--retry-once-with-cleanup=true
    # - --tf-init-args=-upgrade

- id: terraform_providers_lock
  args:
  - --hook-config=--mode=always-regenerate-lockfile

Why? When v2.x will be introduced - the default mode will be changed, probably, to only-check-is-current-lockfile-cross-platform.

You can check available modes for hook below.

  1. The hook can work in a few different modes: only-check-is-current-lockfile-cross-platform with and without terraform_validate hook and always-regenerate-lockfile - only with terraform_validate hook.

    • only-check-is-current-lockfile-cross-platform without terraform_validate - only checks that lockfile has all required SHAs for all providers already added to lockfile.

      - id: terraform_providers_lock
  args:
  - --hook-config=--mode=only-check-is-current-lockfile-cross-platform

    • only-check-is-current-lockfile-cross-platform with terraform_validate hook - make up-to-date lockfile by adding/removing providers and only then check that lockfile has all required SHAs.

      Important Next terraform_validate flag requires additional dependency to be installed: jq. Also, it could run another slow and time consuming command - terraform init

      - id: terraform_validate
  args:
    - --hook-config=--retry-once-with-cleanup=true

- id: terraform_providers_lock
  args:
  - --hook-config=--mode=only-check-is-current-lockfile-cross-platform

    • always-regenerate-lockfile only with terraform_validate hook - regenerate lockfile from scratch. Can be useful for upgrading providers in lockfile to latest versions

      - id: terraform_validate
  args:
    - --hook-config=--retry-once-with-cleanup=true
    - --tf-init-args=-upgrade

- id: terraform_providers_lock
  args:
  - --hook-config=--mode=always-regenerate-lockfile

  2. terraform_providers_lock supports custom arguments:

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

  3. 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 . \( -iname ".terraform*" ! -iname ".terraform-docs*" \) -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.

  4. terraform_providers_lock support passing custom arguments to its terraform init:

    Warning
    DEPRECATION NOTICE: This is available only in no-mode mode, which will be removed in v2.0. Please provide this keys to terraform_validate hook, which, to take effect, should be called before terraform_providers_lock

    - id: terraform_providers_lock
  args:
    - --tf-init-args=-upgrade

terraform_tflint

  1. terraform_tflint supports custom arguments so you can enable module inspection, enable / disable rules, etc.

    Example:

    - id: terraform_tflint
  args:
    - --args=--module
    - --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 the Git working directory (repo root) at run time. For example:

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

  3. By default, pre-commit-terraform performs directory switching into the terraform modules for you. If you want to delegate the directory changing to the binary - this will allow tflint to determine the full paths for error/warning messages, rather than just module relative paths. Note: this requires tflint>=0.44.0. For example:

    - id: terraform_tflint
      args:
        - --hook-config=--delegate-chdir

terraform_tfsec (deprecated)

DEPRECATED. tfsec was replaced by trivy, so please use terraform_trivy.

  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_trivy

  1. terraform_trivy 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_trivy
  files: ^prd-infra/

    The above will tell pre-commit to pass down files from the prd-infra/ folder only such that the underlying trivy 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:

    #trivy:ignore:AVD-AWS-0107
#trivy:ignore:AVD-AWS-0124
resource "aws_security_group_rule" "my-rule" {
    type = "ingress"
    cidr_blocks = ["0.0.0.0/0"]
}

  3. terraform_trivy supports custom arguments, so you can pass supported --format (output), --skip-dirs (exclude directories) and other flags:

     - id: terraform_trivy
    args:
      - --args=--format=json
      - --args=--skip-dirs="**/.terraform"

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

    - id: terraform_trivy
  args:
    - --args=--ignorefile=__GIT_WORKING_DIR__/.trivyignore

terraform_validate

Important

If you use TF_PLUGIN_CACHE_DIR, we recommend enabling --hook-config=--retry-once-with-cleanup=true or disabling parallelism (--hook-config=--parallelism-limit=1) to avoid race conditions when terraform init writes to it.

  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 passing custom arguments to its terraform init:

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

  3. 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 delete broken .terraform directories in your repository:

    Option 1

    - id: terraform_validate
  args:
    - --hook-config=--retry-once-with-cleanup=true     # Boolean. true or false

    Important
    The flag requires additional dependency to be installed: jq.

    Note
    Reinit can be very slow and require downloading data from remote Terraform registries, and not all of that downloaded data or meta-data is currently being cached by Terraform.

    When --retry-once-with-cleanup=true, in each failed directory the cached modules and providers from the .terraform directory will be deleted, before retrying once more. To avoid unnecessary deletion of this directory, the cleanup and retry will only happen if Terraform produces any of the following error messages:

    • "Missing or corrupted provider plugins"
    • "Module source has changed"
    • "Module version requirements have changed"
    • "Module not installed"
    • "Could not load plugin"

    Warning
    When using --retry-once-with-cleanup=true, problematic .terraform/modules/ and .terraform/providers/ directories will be recursively deleted without prompting for consent. Other files and directories will not be affected, such as the .terraform/environment file.

    Option 2

    An alternative solution is to find and delete all .terraform directories in your repository:

    echo "
function rm_terraform {
    find . \( -iname ".terraform*" ! -iname ".terraform-docs*" \) -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.

    Caution
    If you use Terraform workspaces, DO NOT use this option (details). Consider the first option, or wait for force-init option implementation.

  4. terraform_validate in a repo with Terraform module, written using Terraform 0.15+ and which uses provider configuration_aliases (Provider Aliases Within Modules), errors out.

    When running the hook against Terraform code where you have provider configuration_aliases defined in a required_providers configuration block, terraform will throw an error like:

    Error: Provider configuration not present To work with <resource> its original provider configuration at provider ["registry.terraform.io/hashicorp/aws"].<provider_alias> is required, but it has been removed. This occurs when a provider configuration is removed while objects created by that provider still exist in the state. Re-add the provider configuration to destroy <resource>, after which you can remove the provider configuration again.

    This is a known issue with Terraform and how providers are initialized in Terraform 0.15 and later. To work around this you can add an exclude parameter to the configuration of terraform_validate hook like this:

    - id: terraform_validate
  exclude: '^[^/]+$'

    This will exclude the root directory from being processed by this hook. Then add a subdirectory like "examples" or "tests" and put an example implementation in place that defines the providers with the proper aliases, and this will give you validation of your module through the example. If instead you are using this with multiple modules in one repository you'll want to set the path prefix in the regular expression, such as exclude: modules/offendingmodule/[^/]+$.

    Alternately, you can use terraform-config-inspect and use a variant of this script to generate a providers file at runtime:

    terraform-config-inspect --json . | jq -r '
  [.required_providers[].aliases]
  | flatten
  | del(.[] | select(. == null))
  | reduce .[] as $entry (
    {};
    .provider[$entry.name] //= [] | .provider[$entry.name] += [{"alias": $entry.alias}]
  )
' | tee aliased-providers.tf.json

    Save it as .generate-providers.sh in the root of your repository and add a pre-commit hook to run it before all other hooks, like so:

    - repos:
  - repo: local
    hooks:
      - id: generate-terraform-providers
         name: generate-terraform-providers
         require_serial: true
         entry: .generate-providers.sh
         language: script
         files: \.tf(vars)?$
         pass_filenames: false

  - repo: https://github.com/pre-commit/pre-commit-hooks
[...]

    Tip
    The latter method will leave an "aliased-providers.tf.json" file in your repo. You will either want to automate a way to clean this up or add it to your .gitignore or both.

terraform_wrapper_module_for_each

terraform_wrapper_module_for_each generates module wrappers for Terraform modules (useful for Terragrunt where for_each is not supported). When using this hook without arguments it will create wrappers for the root module and all modules available in "modules" directory.

You may want to customize some of the options:

  1. --module-dir=... - Specify a single directory to process. Values: "." (means just root module), "modules/iam-user" (a single module), or empty (means include all submodules found in "modules/*").
  2. --module-repo-org=... - Module repository organization (e.g. "terraform-aws-modules").
  3. --module-repo-shortname=... - Short name of the repository (e.g. "s3-bucket").
  4. --module-repo-provider=... - Name of the repository provider (e.g. "aws" or "google").

Sample configuration:

- id: terraform_wrapper_module_for_each
  args:
    - --args=--module-dir=.   # Process only root module
    - --args=--dry-run        # No files will be created/updated
    - --args=--verbose        # Verbose output

If you use hook inside Docker:
The terraform_wrapper_module_for_each hook attempts to determine the module's short name to be inserted into the generated README.md files for the source URLs. Since the container uses a bind mount at a static location, it can cause this short name to be incorrect.
If the generated name is incorrect, set them by providing the module-repo-shortname option to the hook:

- id: terraform_wrapper_module_for_each
  args:
    - '--args=--module-repo-shortname=ec2-instance'

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 scanning output. Useful 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.

tfupdate

  1. Out of the box tfupdate will pin the terraform version:

    - id: tfupdate
  name: Autoupdate Terraform versions

  2. If you'd like to pin providers, etc., use custom arguments, i.e provider=PROVIDER_NAME:

    - id: tfupdate
  name: Autoupdate AWS provider versions
  args:
    - --args=provider aws # Will be pined to latest version

- id: tfupdate
  name: Autoupdate Helm provider versions
  args:
    - --args=provider helm
    - --args=--version 2.5.0 # Will be pined to specified version

Check tfupdate usage instructions for other available options and usage examples.
No need to pass --recursive . as it is added automatically.

terragrunt_providers_lock

Tip

Use this hook only in infrastructure repos managed solely by terragrunt and do not mix with terraform_providers_lock to avoid conflicts.

Warning

Hook may be very slow, because terragrunt invokes t init under the hood.

Hook produces same results as terraform_providers_lock, but for terragrunt root modules.

It invokes terragrunt providers lock under the hood and terragrunt does its' own magic for handling lock files.

- id: terragrunt_providers_lock
  name: Terragrunt providers lock
  args:
    - --args=-platform=darwin_arm64
    - --args=-platform=darwin_amd64
    - --args=-platform=linux_amd64

terragrunt_validate_inputs

Validates Terragrunt unused and undefined inputs. This is useful for keeping configs clean when module versions change or if configs are copied.

See the Terragrunt docs for more details.

Example:

- id: terragrunt_validate_inputs
  name: Terragrunt validate inputs
  args:
    # Optionally check for unused inputs
    - --args=--terragrunt-strict-validate

Note

This hook requires authentication to a given account if defined by config to work properly. For example, if you use a third-party tool to store AWS credentials like aws-vault you must be authenticated first.

See docs for the iam_role attribute and --terragrunt-iam-role flag for more.

Docker Usage

File Permissions

A mismatch between the Docker container's user and the local repository file ownership can cause permission issues in the repository where pre-commit is run. The container runs as the root user by default, and uses a tools/entrypoint.sh script to assume a user ID and group ID if specified by the environment variable USERID.

The recommended command to run the Docker container is:

TAG=latest
docker run -e "USERID=$(id -u):$(id -g)" -v $(pwd):/lint -w /lint ghcr.io/antonbabenko/pre-commit-terraform:$TAG run -a

which uses your current session's user ID and group ID to set the variable in the run command. Without this setting, you may find files and directories owned by root in your local repository.

If the local repository is using a different user or group for permissions, you can modify the USERID to the user ID and group ID needed. Do not use the username or groupname in the environment variable, as it has no meaning in the container. You can get the current directory's owner user ID and group ID from the 3rd (user) and 4th (group) columns in ls output:

$ ls -aldn .
drwxr-xr-x 9 1000 1000 4096 Sep  1 16:23 .

Download Terraform modules from private GitHub repositories

If you use a private Git repository as your Terraform module source, you are required to authenticate to GitHub using a Personal Access Token.

When running pre-commit on Docker, both locally or on CI, you need to configure the ~/.netrc file, which contains login and initialization information used by the auto-login process.

This can be achieved by firstly creating the ~/.netrc file including your GITHUB_PAT and GITHUB_SERVER_HOSTNAME

# set GH values (replace with your own values)
GITHUB_PAT=ghp_bl481aBlabl481aBla
GITHUB_SERVER_HOSTNAME=github.com

# create .netrc file
echo -e "machine $GITHUB_SERVER_HOSTNAME\n\tlogin $GITHUB_PAT" >> ~/.netrc

The ~/.netrc file will look similar to the following:

machine github.com
  login ghp_bl481aBlabl481aBla

Tip

The value of GITHUB_SERVER_HOSTNAME can also refer to a GitHub Enterprise server (i.e. github.my-enterprise.com).

Finally, you can execute docker run with an additional volume mount so that the ~/.netrc is accessible within the container

# run pre-commit-terraform with docker
# adding volume for .netrc file
# .netrc needs to be in /root/ dir
docker run --rm -e "USERID=$(id -u):$(id -g)" -v ~/.netrc:/root/.netrc -v $(pwd):/lint -w /lint ghcr.io/antonbabenko/pre-commit-terraform:latest run -a

Github Actions

You can use this hook in your GitHub Actions workflow togehther with pre-commit. To easy up dependency management, you can use the managed docker image within your workflow. Make sure to set the image tag to the version you want to use.

In this repository's pre-commit workflow file we run pre-commit without the container image.

Here is an example that use the container image, includes caching of pre-commit dependencies and uses the pre-commit command to run the checks (but fixes will be not automatically push back to your branch, when it possible):

name: pre-commit-terraform

on:
  pull_request:

jobs:
  pre-commit:
    runs-on: ubuntu-latest
    container:
      image: ghcr.io/antonbabenko/pre-commit-terraform:latest # latest used here for simplicity, not recommended
    defaults:
      run:
        shell: bash
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
          ref: ${{ github.event.pull_request.head.sha }}

      - run: |
          git config --global --add safe.directory $GITHUB_WORKSPACE
          git fetch --no-tags --prune --depth=1 origin +refs/heads/*:refs/remotes/origin/*

      - name: Get changed files
        id: file_changes
        run: |
          export DIFF=$(git diff --name-only origin/${{ github.base_ref }} ${{ github.sha }})
          echo "Diff between ${{ github.base_ref }} and ${{ github.sha }}"
          echo "files=$( echo "$DIFF" | xargs echo )" >> $GITHUB_OUTPUT

      - name: fix tar dependency in alpine container image
        run: |
          apk --no-cache add tar
          # check python modules installed versions
          python -m pip freeze --local

      - name: Cache pre-commit since we use pre-commit from container
        uses: actions/cache@v4
        with:
          path: ~/.cache/pre-commit
          key: pre-commit-3|${{ hashFiles('.pre-commit-config.yaml') }}

      - name: Execute pre-commit
        run: |
          pre-commit run --color=always --show-diff-on-failure --files ${{ steps.file_changes.outputs.files }}

Authors

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

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License

MIT licensed. See LICENSE for full details.

Additional information for users from Russia and Belarus

About

pre-commit git hooks to take care of Terraform configurations 🇺🇦

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