Grafana Tanka — Jsonnet-Based Kubernetes Configuration

Introduction

Grafana Tanka is a Kubernetes configuration tool that uses Jsonnet as its templating language. Developed by Grafana Labs, it replaces static YAML manifests with programmable Jsonnet code and provides a CLI for diffing, applying, and managing environments.

What Tanka Does

• Generates Kubernetes manifests from Jsonnet source files
• Manages multiple environments (dev, staging, production) with shared base configurations
• Shows diffs between the desired state and the live cluster before applying
• Integrates with jsonnet-bundler (jb) for dependency management of Jsonnet libraries
• Exports rendered YAML for use with other deployment tools or GitOps pipelines

Architecture Overview

Tanka evaluates Jsonnet files into a JSON object of Kubernetes resources. Each environment has a main.jsonnet entrypoint and spec.json defining the target cluster. Jsonnet code imports libraries like k8s-libsonnet for typed K8s object constructors. Tanka's CLI evaluates Jsonnet, extracts individual objects, then diffs or applies them via the Kubernetes API.

Self-Hosting & Configuration

• Single binary (tk) with no daemon or server component
• Each environment is a directory with spec.json (cluster endpoint, namespace) and main.jsonnet
• Dependencies managed via jsonnet-bundler (jb) with a jsonnetfile.json manifest
• Supports inline environments for smaller projects without directory structure
• Connects to clusters using standard kubeconfig files and kubectl context

Key Features

• Jsonnet eliminates YAML repetition through variables, functions, and object merging
• Environment abstraction manages per-cluster differences from a shared code base
• Native diff command compares rendered output against live cluster state
• Export mode renders all manifests to static YAML files for GitOps workflows
• Helm chart support allows importing Helm charts as Jsonnet objects

Comparison with Similar Tools

• Helm — Template-based with Go templating; Tanka uses Jsonnet which is a full data language
• Kustomize — Overlay-based YAML patching; Tanka offers richer programmability via Jsonnet
• Pulumi — General-purpose IaC; Tanka is Kubernetes-focused with Jsonnet
• cdk8s — Generates K8s manifests from TypeScript/Python; Tanka uses Jsonnet with native diffing

FAQ

Q: Do I need to learn Jsonnet to use Tanka? A: Yes. Jsonnet is Tanka's core language. Its syntax is a superset of JSON, so the learning curve is manageable for developers familiar with JSON.

Q: Can Tanka work alongside Helm? A: Yes. Tanka can import Helm charts and render them as Jsonnet objects, allowing you to combine Helm charts with native Jsonnet configuration.

Q: How does Tanka handle multiple clusters? A: Each environment in Tanka points to a specific cluster via spec.json. You create separate environment directories sharing common Jsonnet libraries but targeting different API servers.

Q: Is Tanka used in production? A: Yes. Grafana Labs uses Tanka to manage their production Kubernetes clusters, and the project is actively maintained.

Sources

• https://github.com/grafana/tanka
• https://tanka.dev/tutorial/overview