yesod-mirror/k8s/configs/templates/README.md

Kubernetes Configuration Templates

This directory contains Jsonnet templates that define reusable application configurations. Many of these templates wrap Helm charts.

Creating a Template for a Helm Chart

To create a template that wraps a Helm chart:

1. Ensure the Chart is Available:

   • Add the chart to third_party/helm/chartfile.yaml.
   • Run bazel run //tools:helm_sync to update the lockfile.
   • Add the generated repository name (e.g., helm_jetstack_cert_manager) to MODULE.bazel in the helm_deps use_repo list.

2. Create the Libsonnet File:

   • Import base.libsonnet.
   • Define a Params struct.
   • Define an App function that calls params.context.helm.template.
   • Path Resolution: The chartPath passed to helm.template must be relative to the caller (this libsonnet file) and point to the external repository. In the Bazel sandbox, this usually looks like ../../external/+helm_deps+repo_name.

   local base = import "k8s/configs/base.libsonnet";
   
   local Params = base.SimpleFieldStruct(["namespace", "name", "context", "values"]);
   
   local App(params) = {
       local chartPath = "../../external/+helm_deps+my_chart_repo",
       app: params.context.helm.template(params.name, chartPath, {
           namespace: params.namespace,
           values: params.values,
       })
   };
   
   { Params: Params, App: App }
   

3. Update BUILD.bazel:

   • Ensure the jsonnet_library target in this directory includes the new file.
   • In the environment's BUILD.bazel (e.g., k8s/configs/environments/my-app/BUILD.bazel), add the chart's filegroup to the data attribute of jsonnet_to_json.

   jsonnet_to_json(
       name = "main",
       ...
       data = [
           "@helm_deps_my_chart_repo//:chart",
       ],
   )
   

Import Paths

When importing tanka-util or other external libraries, use the path relative to the repository root. rules_jsonnet configured with deps adds the repository root to the import path.

Example:

local tanka = import "tanka-util/main.libsonnet";

(Assuming tanka-util directory is at the root of the dependency).