atlantis VS OPA (Open Policy Agent)

None of these are a replacement of Terraform Cloud (recently rebranded to HCP Terraform). For example, when you create a PR, it could affect multiple workspaces. The new experimental version of TFC/TFE (I refuse to call it HCP!) implements Stacks, which is something like a workflow, and links one workspace output to other workspace inputs. None of the open-source solutions, including the paid Digger [0], support this - only the paid one, such as Spacelift [1] (which is the closest to TFC if you ask me). Having a monorepo of Terraform is a common design pattern, so, if I change an embedded module, it could trigger changes it many workspaces. As far as I know, Atlantis [2] can't really help in this case.

By the way, the reason I singled-out Spacelift is due to its quality, and the great Terraform provider it has. Scalr [3], for example, has a really low-quality Terraform provider. I extensively use the hashicorp/tfe provider to manage TFC itself.

[0]: https://digger.dev/

[1]: https://spacelift.io/

[2]: https://www.runatlantis.io/

[3]: https://www.scalr.com/

Atlantis is a pull request automation tool that works well with plain Terraform right away. But what if we're already using Terramate to generate Terraform code?

Atlantis automates reviewing and deploying Terraform via pull requests, streamlining collaboration and ensuring consistency across Terraform deployments.

For example, Atlantisgo for Terraform, Zapier’s Kubechecks for Argo CD, Quizlet’s GitHub action all do something similar to this. But a generic, extensible tool for IaC providers doesn’t seem to exist. Additionally, many of them require exposing your Kubernetes cluster or other infrastructure to third-party access, webhooks, etc.

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.

Alternatively, you can look at solutions like Atlantis or spacelift.

Atlantis: https://www.runatlantis.io/

Looking at the commits at https://github.com/runatlantis/atlantis, it looks like 1.6.5. Am I right?

We use Atlantis [0] for CI/CD automation of Terraform pull requests to a centralized repository. It's pretty good too, especially for a self-hosted solution. I can't see how Terraform Cloud's costs would be justifiable for us without a custom contract.

[0] https://www.runatlantis.io/

How can we handle this? Are there any mechanisms to prevent or at least to some extent safeguard this kind of issues without falling back to a manual workflow? There is. One huge advantage of sticking to (de-facto) standards like Terraform is that first we are probably not the first ones to come up with this question and second there is a huge ecosystem around Terraform that might help us with such challenges. And for this specific scenario the solution is the Open Policy Agent. Let us take a closer look how the solution could look like.

A popular Policy-as-Code tool for Terraform is OPA, everyone's favorite versatile open-source policy engine that enforces security and compliance policies across your cloud-native stack, making it easier to manage and maintain consistent policy enforcement in complex, multi-service environments.

Harness Policy As Code uses Open Policy Agent (OPA) as the central service to store and enforce policies for the different entities and processes across the Harness platform. In this section, you will define a policy that will deny a pipeline execution if there is no approval step defined in a deployment stage.

OPA: While OPA is an open-source, general-purpose policy engine capable of enforcing unified and context-aware policies throughout the stack, it can also accept and output data in formats such as JSON, effectively functioning as a tool for generating or modifying configurations. Although it does not provide out-of-the-box schema definition support, it allows the integration of JsonSchema definitions.

In essence, container image signing involves adding a digital stamp to an image, affirming its authenticity. This digital assurance guarantees that the image is unchanged from creation to deployment. In this blog, I'll explain how to sign container images for Kubernetes using Cosign and the Open Policy Agent. I will also share a tutorial that demonstrates these concepts.

In this post we will explores two powerful solutions for addressing this issue: the Open Policy Language (OPA) and Google’s Zanzibar.

Rego is a declarative query language from the makers of the Open Policy Agent (OPA) framework. The Cloud Native Computing Foundation (CNCF) accepted OPA as an incubation-level hosted project in April 2019, and OPA graduated from incubating status in 2021.

Now there are more subdivided practice: * Policy as Code: Sentinel, OPA * Database as Code: bytebase * AppConfiguration as Code: KusionStack, Acorn * ...... (Welcome to add more)