awesome-kubernetes/docs/yaml.md

Templating YAML with YAML Processors. Static Checking of Kubernetes YAML Files

Templating YAML Files

• wikipedia: YAML
• thoughtworks.com: Templating in YAML As infrastructures grow in complexity, so do the configuration files that define them. Tools such as AWS CloudFormation, Kubernetes and Helm expect configuration files in JSON or YAML syntax, presumably in an attempt to make them easy to write and process. However, in most cases, teams quickly reach the point where they have some parts that are similar but not quite the same, for example, when the same service must be deployed in different regions with a slightly different setup. For such cases tools offer templating in YAML (or JSON), which has caused a huge amount of frustration with practitioners. The problem is that the syntax of JSON and YAML requires all sorts of awkward compromises to graft templating features such as conditionals and loops into the files. We recommend using an API from a programming language instead or, when this is not an option, a templating system in a programming language, either a general-purpose language such as Python or something specialized such as Jsonnet.
• Steve Horsfield: DevOps tricks - Templating YAML files Basic text tools fall foul of YAML’s indentation sensitivity. On the other hand, YAML tools like ytt are pretty difficult to interpret. In my case, I opted for a small jq program executed via yq.

YAML Processors

• github.com/topics/yaml-processor
• ytt is a templating tool that understands YAML structure allowing you to focus on your data instead of how to properly escape it.
• You should use tools such as yq and kustomize to template YAML resources instead of relying on tools that interpolate strings such as Helm.
• yq 🌟 is a lightweight and portable command-line YAML processor. The aim of the project is to be the jq or sed of yaml files. yq allows to query the yaml tree and highlights it: k get svc a -oyaml | yq r -
  • dev.to: yq : A command line tool that will help you handle your YAML resources better 🌟
• Kapitan Generic templated configuration management for Kubernetes, Terraform and other things.
• yaml.sh A YAML parser completely in bash. Yaml.sh — YAML Sans Helm
• yh - YAML Highlighter is YAML syntax highlighter that works nicely with kubectl output
• Kubectl output options 🌟

Templating JSON Files

• wikipedia: JSON
• Jsonnet A data templating language for app and tool developers
• Building a high performance JSON parser

Static Checking of Kubernetes YAML Files

• The ecosystem of static checking of Kubernetes YAML files can be grouped in the following categories:
  • API validators: Tools in this category validate a given YAML manifest against the Kubernetes API server.
  • Built-in checkers: Tools in this category bundle opinionated checks for security, best practices, etc.
  • Custom validators: Tools in this category allow writing custom checks in several languages such as Rego and Javascript.
• Validating Kubernetes YAML for best practice and policies 🌟 In this article, you will learn and compare six different tools:
  • Kubeval
  • Kube-score
  • Config-lint
  • Copper
  • Conftest
  • Polaris