hcl VS OPA (Open Policy Agent)

Terraform HCL (HashiCorp Configuration Language) is an essential language for cloud engineers in 2024, particularly for those involved in infrastructure as code (IaC) practices. HCL is the configuration language used by Terraform, a widely adopted tool that enables engineers to define, provision, and manage cloud infrastructure using a declarative configuration approach. Learning Terraform HCL allows cloud engineers to automate the deployment and lifecycle management of cloud resources across various service providers, ensuring consistency, repeatability, and scalability of cloud environments.

Reminds me of [HCL](https://github.com/hashicorp/hcl), but without all the providers to deploy the config?

HCL: A Go implementation structured configuration language. The native syntax of HCL is inspired by libucl and nginx configurations. It is used to create a structured configuration language that is friendly to humans and machines, mainly for DevOps tools, server configurations, and resource configurations as a Terraform language.

HCL has a JSON representation [1], internally, objects behave that way. so it should be possible to write a Jsonnet wrapper around it. Terraform can currently parse json pipelines too.

[1]: https://github.com/hashicorp/hcl/blob/main/json/spec.md

>https://noyaml.com/

I'm not sure this is the criticism you think it is. Wow, so you basically have to add quotes to get strings in some ambiguous situations?

Yeah sure you could probably improve YAML by getting rid of these weird pitfalls, but that is a minor improvement. The alternative isn't something like TOML, because YAML is optimized for hierarchical configuration. It's every vendor implementing a different syntax such as Hashicorp with their HCL [0].

[0] https://github.com/hashicorp/hcl

The Hashicorp corporation has made a huge impact in providing valuable tools and platforms in the cloud ecosystem. The advantage of using the tools they provide, such as Terraform, Vault, and Packer, is that they all have the same language, Hashicorp Configuration Language (HCL). This means you can easily pick up any of these tools by learning HCL, which is similar to JSON. This approach can be useful when choosing tools to learn or use for a project.

Format is HCL language feature: https://github.com/hashicorp/hcl/blob/main/hclwrite/public.go

Hi, from what I read from HCL Github "HCL is a syntax and API specifically designed for building structured configuration formats.".

When the desired state is relatively simple to define and the mechanism to reach that state is not that important, writing up a declaration of what is needed and letting something/someone else deal with it is the most logical abstraction. This would be like drafting up the architectural draft for your new restaurant and paying a contracting company to actually build it, or writing HTML and letting a web browser render it, or writing a Terraform HCL file and letting the Terraform CLI tool apply it. This is called declarative programming in the software world, and has many advantages (and a few disadvantages!) for cloud infrastructure management.

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)