gatekeeper-library VS conftest

Here is a library or rules for the Open Policy Agent.

https://github.com/open-policy-agent/gatekeeper-library is the library of OPA Gatekeeper policies.

Many more examples are available in the OPA Gatekeeper library project!

by default and exposes metrics on path ```/metrics``` . It can run locally on your development box as long as you have a valid Kubernetes configuration in your home folder (i.e. if you can run kubectl and have the right permissions). When running on the cluster a ```incluster``` parameter is passed in so that it knows where to look up for the cluster credentials. Exporter program connects to Kubernetes API every 10 seconds to scrape data from Kubernetes API. We've used [this](https://medium.com/teamzerolabs/15-steps-to-write-an-application-prometheus-exporter-in-go-9746b4520e26) blog post as the base for the code. ## Demo Let's go ahead and prepare our components so that we have a Grafana dashboard to show us which constraints have been violated and how the number of violations evolve over time. ### 0) Required tools - [Git](https://git-scm.com/downloads): A git cli is required to checkout the repo and - [Kubectl](https://kubernetes.io/docs/tasks/tools/) and a working K8S cluster - [Ytt](https://carvel.dev/ytt/): This is a very powerful yaml templating tool, in our setup it's used for dynamically overlaying a key/value pair in all constraints. It's similar to Kustomize, it's more flexibel than Kustomize and heavily used in some [Tanzu](https://tanzu.vmware.com/tanzu) products. - [Kustomize](https://kustomize.io/): Gatekeeper-library relies on Kustomize, so we need it too. - [Helm](https://helm.sh/): We will install Prometheus and Grafana using helm - Optional: [Docker](https://www.docker.com/products/docker-desktop): Docker is only optional as we already publish the required image on dockerhub. ### 1) Git submodule update Run ```git submodule update --init``` to download gatekeeper-library dependency. This command will download the [gatekeeper-library](https://github.com/open-policy-agent/gatekeeper-library) dependency into folder ```gatekeeper-library/library``` . ### 2) Install OPA/Gatekeeper If your K8S cluster does not come with Gatekeeper preinstalled, you can use install it as explained [here](https://open-policy-agent.github.io/gatekeeper/website/docs/install/). If you are familiar with helm, the easiest way to install is as follows: ```bash helm repo add gatekeeper https://open-policy-agent.github.io/gatekeeper/charts helm install gatekeeper/gatekeeper --generate-name

Gatekeeper library has example policies for restricting image repositories: https://github.com/open-policy-agent/gatekeeper-library/tree/master/library/general

You should check out the Gatekeeper project. There's plenty of templates available for use without having to write a single line of rego for most use cases (e.g https://github.com/open-policy-agent/gatekeeper-library)

I wrote following conftest.dev (OPA), sample policy

name: tf-plan-apply on: pull_request: branches: [ main ] env: TF_VERSION: 1.0.0 CONFTEST_VERSION: 0.28.3 WORKING_DIR: ./ jobs: terraform: name: aws-eureka-pairs-etc-s3 runs-on: ubuntu-latest steps: - name: Checkout uses: actions/checkout@v2 - name: Install conftest run: | wget -O - 'https://github.com/open-policy-agent/conftest/releases/download/v${{ env.CONFTEST_VERSION }}/conftest_${{ env.CONFTEST_VERSION }}_Linux_x86_64.tar.gz' | tar zxvf - ./conftest --version //❶ - name: Setup Terraform uses: hashicorp/setup-terraform@v1 with: terraform_wrapper: false //❷ terraform_version: ${{ env.TF_VERSION }} cli_config_credentials_token: ${{ secrets.YOUR_CRED_NAME}} - name: Terraform Init ${{ env.WORKING_DIR }} working-directory: ${{ env.WORKING_DIR }} run: terraform init - name: Terraform Plan ${{ env.WORKING_DIR }} if: github.event_name == 'pull_request' env: GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} working-directory: ${{ env.WORKING_DIR }} id: plan run: terraform plan -out=tfplan -no-color -lock=false -parallelism=50 - name: Convert terraform plan result to json formmat if: github.event_name == 'pull_request' id: convert working-directory: ${{ env.WORKING_DIR }} run: terraform show -json tfplan > tfplan.json - name: conftest test if: github.event_name == 'pull_request' id: conftest run: ./conftest test --no-color ${{ env.WORKING_DIR }}/tfplan.json //❸

Workload configuration should be audited regularly (Kics, Kubeaudit, Kubescape, Conftest, Kubesec, Checkov)

Insert Conftest! As they state in their GitHub description, Conftest tests against structured configuration data using the Open Policy Agent Rego query language. In the case of Terraform, this means we're actually running unit tests against sample JSON and actual tests against the Terraform state JSON.

While Rego is the policy language we use to assemble our policies, we still need something to run those policies with. If you have a cluster and you want to actively evaluate policies, you can end up running an instance of Open Policy Agent and it's associated tooling. However in our case, we just want to check things at runtime (or just on some recurring basis such as when changes get checked in or a pull request is submitted). In the latter instance, we are able to use another tool from the Open Policy Agent project called ConfTest. What ConfTest allows us to do is to specify a file or directory of files that we want to inspect along with the set of policies we want to inspect them with. It then takes all of that and dumps out the associated outputs from those policies and tell us the results (i.e. the messages, how many policies were checked and the results of those policies). This tool is much better suited for our use case, so this is what we will proceed with. To grab the latest version of ConfTest, you can grab the latest release from here.

OR HOW TO RUN https://github.com/open-policy-agent/conftest AS CI/CD in Circle CI to apply policies?

If you like terraform-compliance, Conftest might also be worth having a look. It has its own DSL to write policies, and allows you to test multiple frameworks. We found this blog post from Lennard Eijsackers very informative, and would thus rather recommend you to check it out.

Can Gatekeeper and Conftest single-source the same set of rules? I'm looking at https://github.com/open-policy-agent/conftest/issues/54#issuecomment-528988831 and not seeing how.