dhall-lang VS terragrunt

Fail to see how this is any different than Dhall (https://dhall-lang.org/) other than it produces plists too.

Kubernetes config is a decent example. I had ChatGPT generate a representative silly example -- the content doesn't matter so much as the structure:

https://gist.github.com/cstrahan/528b00cd5c3a22e3d8f057bb1a7...

Now consider 100s (if not 1000s) of such files.

I haven't given Pkl an in depth look yet, but I can say that the Industry Standard™ of "simple YAML" + string substitution (with delicate, error prone indentation -- since YAML is indentation sensitive) is easily beat by any of:

- https://jsonnet.org/

- https://nickel-lang.org/

- https://nixos.org/manual/nix/stable/language/index.html

- https://dhall-lang.org/

- (insert many more here, probably including Pkl)

There are underpowered languages / tools, that can only solve a problem for which they are intended poorly. But not all limited tools are like that.

Say, eBPF is prominently not Turing-complete, which allows to guarantee that a eBPF program terminates, and even how soon. Still eBPF is hugely useful in its area.

Or, say, regular expressions are limited to regular languages; in particular, they famously [1] cannot process recursive structures, like trees. Still tools like grep / ag / rg are mightily useful.

Yes, I agree that YAML is underpowered for proper k8s configuration! But it's also too powerful for its own good in other aspects [2]. I wish Google used Dhall [3] or their own purely functional config language (FCL? I already forgot the name) instead of YAML; sadly, they did not.

[1]: https://stackoverflow.com/a/1732454/223424

[2]: https://ruudvanasseldonk.com/2023/01/11/the-yaml-document-fr...

[3]: https://dhall-lang.org/

Dhall: Dhall is a programmable configuration language that combines features like JSON, functions, types, and import capabilities. Its style leans towards functional programming, so if you're familiar with functional-style languages such as Haskell, you might find Dhall to be quite intuitive.

I've been thinking along these lines but more 'strongly validated' than statically typed in the sense that you'd be better off being able to load the entire config and then produce a list of problems (and should be able to offer good editor support if done correctly).

Though https://dhall-lang.org/ demonstrates that you can statically type quite a lot of configuration to great advantage, which appears to be programmatically embeddable in multiple languages per https://docs.dhall-lang.org/howtos/How-to-integrate-Dhall.ht...

> Where practical is in the sense of an engineer (or in their terms, a CS practitioner),

Configuration processing. E.g. I'd like my yamls to be decidable, though I'd settle for guaranteed to halt[1].

[1] https://dhall-lang.org/

Maybe you'd like jsonnet: https://jsonnet.org/

I find it particularly useful for configurations that often have repeated boilerplate, like ansible playbooks or deploying a bunch of "similar-but" services to kubernetes (with https://tanka.dev).

Dhall is also quite interesting, with some tradeoffs: https://dhall-lang.org/

A few years ago I did a small comparison by re-implementing one of my simpler ansible playbooks: https://github.com/retzkek/ansible-dhall-jsonnet

And to checkout Dhall: https://dhall-lang.org/

Terragrunt is a Terraform wrapper, designed to fill in the gaps when it comes to large scale Terraform configurations.

name: Configure on: push: branches: - main pull_request: branches: - main workflow_dispatch: inputs: destroy: description: 'Run Terragrunt destroy command' required: true default: 'false' type: choice options: - true - false jobs: apply: if: ${{ !inputs.destroy || inputs.destroy == 'false' }} runs-on: ubuntu-latest steps: - name: Checkout repository uses: actions/checkout@v2 - name: Setup SSH uses: webfactory/[email protected] with: ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }} - name: Setup Terraform uses: hashicorp/setup-terraform@v2 with: terraform_version: 1.5.5 terraform_wrapper: false - name: Setup Terragrunt run: | curl -LO "https://github.com/gruntwork-io/terragrunt/releases/download/v0.48.1/terragrunt_linux_amd64" chmod +x terragrunt_linux_amd64 sudo mv terragrunt_linux_amd64 /usr/local/bin/terragrunt terragrunt -v - name: Apply Terraform changes run: | cd dev terragrunt run-all apply -auto-approve --terragrunt-non-interactive -var AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID -var AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY -var AWS_REGION=$AWS_DEFAULT_REGION env: AWS_ACCESS_KEY_ID: ${{ vars.AWS_ACCESS_KEY_ID }} AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }} AWS_DEFAULT_REGION: ${{ vars.AWS_DEFAULT_REGION }} destroy: if: ${{ inputs.destroy == 'true' }} runs-on: ubuntu-latest steps: - name: Checkout repository uses: actions/checkout@v2 - name: Setup SSH uses: webfactory/[email protected] with: ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }} - name: Setup Terraform uses: hashicorp/setup-terraform@v2 with: terraform_version: 1.5.5 terraform_wrapper: false - name: Setup Terragrunt run: | curl -LO "https://github.com/gruntwork-io/terragrunt/releases/download/v0.48.1/terragrunt_linux_amd64" chmod +x terragrunt_linux_amd64 sudo mv terragrunt_linux_amd64 /usr/local/bin/terragrunt terragrunt -v - name: Destroy Terraform changes run: | cd dev terragrunt run-all destroy -auto-approve --terragrunt-non-interactive -var AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID -var AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY -var AWS_REGION=$AWS_DEFAULT_REGION env: AWS_ACCESS_KEY_ID: ${{ vars.AWS_ACCESS_KEY_ID }} AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }} AWS_DEFAULT_REGION: ${{ vars.AWS_DEFAULT_REGION }}

‍Terragrunt is a thin wrapper that provides extra tools for keeping your Terraform configurations DRY (Don't Repeat Yourself), working with multiple Terraform modules, and managing remote state. It's particularly useful in managing large-scale infrastructure deployments with Terraform.

... #************************** Terraform ************************************* ARG TERRAFORM_VERSION=1.7.3 RUN set -ex \ && curl -O https://releases.hashicorp.com/terraform/${TERRAFORM_VERSION}/terraform_${TERRAFORM_VERSION}_linux_amd64.zip && unzip terraform_${TERRAFORM_VERSION}_linux_amd64.zip -d /usr/local/bin/ RUN set -ex \ && mkdir -p $HOME/.terraform.d/plugin-cache && echo 'plugin_cache_dir = "$HOME/.terraform.d/plugin-cache"' > ~/.terraformrc #************************* Terragrunt ************************************* ARG TERRAGRUNT_VERSION=0.55.1 RUN set -ex \ && wget https://github.com/gruntwork-io/terragrunt/releases/download/v${TERRAGRUNT_VERSION}/terragrunt_linux_amd64 -q \ && mv terragrunt_linux_amd64 /usr/local/bin/terragrunt \ && chmod +x /usr/local/bin/terragrunt #*********************** Terramate **************************************** ARG TERRAMATE_VERSION=0.4.5 RUN set -ex \ && wget https://github.com/mineiros-io/terramate/releases/download/v${TERRAMATE_VERSION}/terramate_${TERRAMATE_VERSION}_linux_x86_64.tar.gz \ && tar -xzf terramate_${TERRAMATE_VERSION}_linux_x86_64.tar.gz \ && mv terramate /usr/local/bin/terramate \ && chmod +x /usr/local/bin/terramate #*********************** tfsec ******************************************** ARG TFSEC_VERSION=1.28.5 RUN set -ex \ && wget https://github.com/aquasecurity/tfsec/releases/download/v${TFSEC_VERSION}/tfsec-linux-amd64 \ && mv tfsec-linux-amd64 /usr/local/bin/tfsec \ && chmod +x /usr/local/bin/tfsec \ && terragrunt --version #**********************Terraform docs ************************************ ARG TERRRAFORM_DOCS_VERSION=0.17.0 RUN set -ex \ && curl -sSLo ./terraform-docs.tar.gz https://terraform-docs.io/dl/v${TERRRAFORM_DOCS_VERSION}/terraform-docs-v${TERRRAFORM_DOCS_VERSION}-$(uname)-amd64.tar.gz \ && tar -xzf terraform-docs.tar.gz \ && chmod +x terraform-docs \ && mv terraform-docs /usr/local/bin/terraform-docs #********************* ShellCheck ***************************************** ARG SHELLCHECK_VERSION="stable" RUN set -ex \ && wget -qO- "https://github.com/koalaman/shellcheck/releases/download/${SHELLCHECK_VERSION?}/shellcheck-${SHELLCHECK_VERSION?}.linux.x86_64.tar.xz" | tar -xJv \ && cp "shellcheck-${SHELLCHECK_VERSION}/shellcheck" /usr/bin/ \ && shellcheck --version ...

Our first attempt was to introduce other engineering teams to Terraform - the Platform team was already using it extensively with Terragrunt, and using Atlantis to automate plan and apply operations in a Git flow to ensure infrastructure was consistent. We'd written modules, with documentation, and an engineer would simply need to raise a PR to use the module and provide the right values, and Atlantis (once the PR was approved by Platform) would go ahead and set it up for them.

Terragrunt: An extension of Terraform, Terragrunt assists in managing complex infrastructure with less duplication and more efficiency. Its power lies in its ability to manage dependencies and its dry configuration approach.

Copy the link and download on your terminal using the wget command. Example: wget https://github.com/gruntwork-io/terragrunt/releases/download/v0.54.19/terragrunt_linux_amd64

name: Configure on: push: branches: - main pull_request: branches: - main jobs: terraform: runs-on: ubuntu-latest steps: - name: Checkout repository uses: actions/checkout@v2 - name: Setup SSH uses: webfactory/[email protected] with: ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }} - name: Setup Terraform uses: hashicorp/setup-terraform@v2 with: terraform_version: 1.5.5 terraform_wrapper: false - name: Setup Terragrunt run: | curl -LO "https://github.com/gruntwork-io/terragrunt/releases/download/v0.48.1/terragrunt_linux_amd64" chmod +x terragrunt_linux_amd64 sudo mv terragrunt_linux_amd64 /usr/local/bin/terragrunt terragrunt -v - name: Apply Terraform changes run: | cd dev terragrunt run-all apply -auto-approve --terragrunt-non-interactive -var AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID -var AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY -var AWS_REGION=$AWS_DEFAULT_REGION cd apache-server/ec2-web-server public_ip=$(terragrunt output instance_public_ip) echo "$public_ip" > public_ip.txt cat public_ip.txt env: AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }} AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }} AWS_DEFAULT_REGION: ${{ secrets.AWS_DEFAULT_REGION }} - name: Upload artifact uses: actions/upload-artifact@v4 with: name: ip-artifact path: dev/apache-server/ec2-web-server/public_ip.txt ansible: runs-on: ubuntu-latest needs: terraform steps: - name: Download artifact uses: actions/download-artifact@v4 with: name: ip-artifact - name: Configure Ansible run: | sudo apt update sudo pipx inject ansible-core jmespath ansible-playbook --version sudo echo "[web]" >> ansible_hosts sudo cat public_ip.txt >> ansible_hosts mv ansible_hosts $HOME sudo cat $HOME/ansible_hosts - name: Configure playbook run: | cd $HOME cat > deploy.yml < Test Page This is a test page EOF cat $HOME/deploy.yml - name: Run playbook uses: dawidd6/action-ansible-playbook@v2 with: playbook: deploy.yml directory: /home/runner key: ${{secrets.SSH_PRIVATE_KEY}} options: | --inventory ansible_hosts --verbose

Created and maintained by Gruntwork, Terragrunt is a tool designed to enhance Terraform’s capabilities. It acts as a thin wrapper around Terraform, offering additional features to streamline and optimise Terraform usage. Key functions of Terragrunt include helping users keep their Terraform configurations DRY (Don’t Repeat Yourself), efficiently managing multiple Terraform modules, and handling remote state management. By reducing repetition in Terraform code and simplifying the management of complex module dependencies and remote state, Terragrunt makes working with Terraform more efficient, especially for larger or more complex infrastructure deployments.

locals { # Automatically load region-level variables region_vars = read_terragrunt_config(find_in_parent_folders("region.hcl")) # Automatically load environment-level variables` environment_vars = read_terragrunt_config(find_in_parent_folders("env.hcl")) # Extract the variables we need for easy access account_name = local.environment_vars.locals.account_name account_id = local.environment_vars.locals.aws_account_id aws_region = local.region_vars.locals.aws_region # This is the S3 bucket where the Terraform State Files will be stored remote_state_bucket = "devops-bucket" # This is the DynamoDB table where Terraform will add the locking status dynamodb_table = "terraform-state-lock" # IAM Role for Terraform backend to assume terraform_backend_role = "arn:aws:iam::{shared-services_account_id}:role/terraform-backend-role" environment_path = replace(path_relative_to_include(), "environments/", "") # https://github.com/hashicorp/terraform/releases terraform_version = "latest" # https://github.com/gruntwork-io/terragrunt/releases terragrunt_version = "latest" } # Generate an AWS provider block generate "provider" { path = "provider.tf" if_exists = "overwrite_terragrunt" contents = <