Krew Release Automation Guide

This document explains how kubescape automates publishing to the Kubernetes plugin package manager, krew.

What is Krew?

Krew is a plugin manager for kubectl. It allows users to discover and install kubectl plugins easily. You can learn more about krew at https://krew.sigs.k8s.io/.

How kubescape publishes to krew

We use the krew-release-bot to automatically create pull requests to the kubernetes-sigs/krew-index repository whenever a new release of kubescape is published.

Setup Overview

The automation consists of three components:

.krew.yaml - A template file that the bot uses to generate the krew plugin manifest
.github/workflows/02-release.yaml - GitHub Actions workflow that runs the krew-release-bot after a successful release
.goreleaser.yaml - GoReleaser configuration that defines the krew manifest (though upload is skipped)

Why Use krew-release-bot Instead of GoReleaser's Built-in Krew Support?

You might have noticed that GoReleaser has built-in krew support in its krews section. However, almost all projects (including stern) use skip_upload: true and rely on krew-release-bot instead. Here's why:

Problems with GoReleaser's Built-in Krew Publishing

To use GoReleaser's direct krew publishing, you would need to:

yaml

krews:
  - name: kubescape
    skip_upload: false  # Instead of true
    repository:
      owner: kubernetes-sigs
      name: krew-index
      token: "{{ .Env.KREW_INDEX_TOKEN }}"  # Required!
      pull_request:
        enabled: true  # Requires GoReleaser Pro for cross-repo PRs

This approach has several critical issues:

Permission Barrier: Almost no one has write access to kubernetes-sigs/krew-index. You would need special permissions from the Krew maintainers, which is rarely granted.
Security Risk: You'd need to store a GitHub personal access token with write access to the krew-index in your repository secrets. This token could be compromised and used to make unauthorized changes to the krew-index.
GoReleaser Pro Required: To create pull requests to a different repository (cross-repository), you need GoReleaser Pro, which is a paid product.
Manual Work: Even if you had access, you'd need to manually configure and maintain the repository settings, tokens, and potentially deal with rate limits and authentication issues.

Why krew-release-bot is the Right Solution

The krew-release-bot was created by the Kubernetes community (in collaboration with the Krew team) specifically to solve these problems:

No Repository Access Required: The bot acts as an intermediary with pre-configured access to krew-index. You don't need write permissions.
No Tokens Needed: It uses GitHub's GITHUB_TOKEN (automatically available in GitHub Actions) via webhooks and events. No personal access tokens required.
Designed for Krew: It's specifically built for the krew-index workflow and integrates with Krew's automation.
Automatic Merging: The Krew team has configured their CI to automatically test and merge PRs from krew-release-bot (usually within 5-10 minutes).
Officially Recommended: The Krew team explicitly recommends this approach in their documentation as the standard way to automate plugin updates.
Free and Open Source: No paid subscriptions required.

The Real-World Evidence

Looking at recent pull requests to kubernetes-sigs/krew-index, almost all automated plugin updates are created by krew-release-bot. You'll see patterns like:

Author: krew-release-bot
Title: "release new version v0.6.11 of radar"

This demonstrates that the entire Kubernetes ecosystem has standardized on krew-release-bot, not GoReleaser's built-in publishing.

Summary

While GoReleaser's built-in krew support exists in the code, it's practically unusable for the krew-index repository due to permission and security constraints. The krew-release-bot is the de facto standard because:

It works without special permissions
It's more secure
It integrates with Krew's automation
It's free and recommended by the Krew team

This is why we use skip_upload: true in GoReleaser and let krew-release-bot handle the actual publishing.

The Template File

The .krew.yaml file in the repository root is a Go template that contains placeholders for dynamic values:

yaml

apiVersion: krew.googlecontainertools.github.com/v1alpha2
kind: Plugin
metadata:
  name: kubescape
spec:
  version: {{ .TagName }}
  platforms:
  - selector:
      matchLabels:
        os: linux
        arch: amd64
    {{ $version := trimPrefix "v" .TagName }}{{ addURIAndSha "https://github.com/kubescape/kubescape/releases/download/" .TagName (printf "kubescape_%s_linux_amd64.tar.gz" $version) .TagName }}
    bin: kubescape
  - selector:
      matchLabels:
        os: linux
        arch: arm64
    {{ $version := trimPrefix "v" .TagName }}{{ addURIAndSha "https://github.com/kubescape/kubescape/releases/download/" .TagName (printf "kubescape_%s_linux_arm64.tar.gz" $version) .TagName }}
    bin: kubescape
  - selector:
      matchLabels:
        os: darwin
        arch: amd64
    {{ $version := trimPrefix "v" .TagName }}{{ addURIAndSha "https://github.com/kubescape/kubescape/releases/download/" .TagName (printf "kubescape_%s_darwin_amd64.tar.gz" $version) .TagName }}
    bin: kubescape
  - selector:
      matchLabels:
        os: darwin
        arch: arm64
    {{ $version := trimPrefix "v" .TagName }}{{ addURIAndSha "https://github.com/kubescape/kubescape/releases/download/" .TagName (printf "kubescape_%s_darwin_arm64.tar.gz" $version) .TagName }}
    bin: kubescape
  - selector:
      matchLabels:
        os: windows
        arch: amd64
    {{ $version := trimPrefix "v" .TagName }}{{ addURIAndSha "https://github.com/kubescape/kubescape/releases/download/" .TagName (printf "kubescape_%s_windows_amd64.tar.gz" $version) .TagName }}
    bin: kubescape.exe
  - selector:
      matchLabels:
        os: windows
        arch: arm64
    {{ $version := trimPrefix "v" .TagName }}{{ addURIAndSha "https://github.com/kubescape/kubescape/releases/download/" .TagName (printf "kubescape_%s_windows_arm64.tar.gz" $version) .TagName }}
    bin: kubescape.exe
  shortDescription: Scan resources and cluster configs against security frameworks.
  description: |
    Kubescape is the first tool for testing if Kubernetes is deployed securely
    according to mitigations and best practices. It includes risk analysis,
    security compliance, and misconfiguration scanning with an easy-to-use
    CLI interface, flexible output formats, and automated scanning capabilities.

    Features:
    - Risk analysis: Identify vulnerabilities and security risks in your cluster
    - Security compliance: Check your cluster against multiple security frameworks
    - Misconfiguration scanning: Detect security misconfigurations in your workloads
    - Flexible output: Results in JSON, SARIF, HTML, JUnit, and Prometheus formats
    - CI/CD integration: Easily integrate into your CI/CD pipeline
  homepage: https://kubescape.io/
  caveats: |
    Requires kubectl and basic knowledge of Kubernetes.
    Run 'kubescape scan' to scan your Kubernetes cluster or manifests.

The {{ .TagName }} is replaced with the release tag (e.g., v3.0.0), {{ trimPrefix "v" .TagName }} removes the version prefix, and {{ addURIAndSha ... }} calculates the SHA256 checksum for the binary archive.

Release Workflow

The release workflow (.github/workflows/02-release.yaml) can be triggered in two ways:

Automatic: When a new tag matching the pattern v[0-9]+.[0-9]+.[0-9]+ is pushed to the repository
Manual: Via workflow_dispatch with an optional skip_publish input

When the workflow is triggered:

GoReleaser builds and publishes the release artifacts (unless skip_publish=true is set)
The krew-release-bot step runs conditionally:
- It runs when triggered by a tag push OR by workflow_dispatch with skip_publish=false
- It skips when triggered by workflow_dispatch with skip_publish=true (default)
When it runs, the bot:
- Reads the .krew.yaml template
- Fills in the template with release information
- Creates a pull request to the kubernetes-sigs/krew-index repository
- The PR is automatically tested and merged by krew's infrastructure

Workflow Permissions

The release job has the following permissions:

yaml

permissions:
  actions: read
  checks: read
  contents: write
  deployments: read
  discussions: read
  id-token: write
  issues: read
  models: read
  packages: write
  pages: read
  pull-requests: read
  repository-projects: read
  statuses: read
  security-events: read
  attestations: read
  artifact-metadata: read

These permissions are necessary for GoReleaser to create releases and upload artifacts.

Testing the Template

Before committing changes to .krew.yaml, you can test how the template will be rendered using Docker:

bash

docker run -v $(pwd)/.krew.yaml:/tmp/.krew.yaml ghcr.io/rajatjindal/krew-release-bot:v0.0.47 \
  krew-release-bot template --tag v3.0.0 --template-file /tmp/.krew.yaml

This will output the generated krew manifest file, allowing you to verify:

The version field is correct
All download URLs are properly formatted
The SHA256 checksum will be calculated correctly

Why skip_upload in GoReleaser?

In .goreleaser.yaml, the krews section has skip_upload: true:

yaml

krews:
  - name: kubescape
    ids:
      - cli
    skip_upload: true  # We use krew-release-bot instead
    homepage: https://kubescape.io/
    description: It includes risk analysis, security compliance, and misconfiguration scanning with an easy-to-use CLI interface, flexible output formats, and automated scanning capabilities.
    short_description: Scan resources and cluster configs against security frameworks.

This is intentional because:

GoReleaser generates the manifest but doesn't have built-in support for submitting PRs to krew-index
krew-release-bot is the recommended tool for krew automation by the Krew team
Using krew-release-bot provides automatic testing and merging of version bump PRs

Manual Release Testing

You can test the release workflow manually without publishing to krew by using workflow_dispatch:

Go to Actions tab in GitHub
Select "02-create_release" workflow
Click "Run workflow"
The skip_publish input defaults to true (publishing will be skipped)
Set skip_publish to false if you want to test the full release process including krew indexing

Making Changes to the Template

If you need to update the krew manifest (e.g., change the description, add platforms, or update the binary location):

Edit the .krew.yaml file
Test your changes with the Docker command shown above
Commit and push the changes
The next release will use the updated template

Installing kubescape via krew

Once the plugin is indexed in krew, users can install it with:

bash

kubectl krew install kubernetes-sigs/kubescape

Or after index update:

bash

kubectl krew install kubescape

Krew Release Automation Guide

Krew Release Automation Guide

What is Krew?

How kubescape publishes to krew

Setup Overview

Why Use krew-release-bot Instead of GoReleaser's Built-in Krew Support?

Problems with GoReleaser's Built-in Krew Publishing

Why krew-release-bot is the Right Solution

The Real-World Evidence

Summary

The Template File

Release Workflow

Workflow Permissions

Testing the Template

Why skip_upload in GoReleaser?

Manual Release Testing

Making Changes to the Template

Installing kubescape via krew

Further Reading