GitHub PR Preview Bot

A lightweight tool that automatically comments on GitHub Pull Requests with deployment preview links.

• Overview
• Quickstart
  • Running locally
  • Kubernetes Integration Example
• Environment Variables
• Template

Overview

This project provides a simple Go application that:

• Posts comments on GitHub PRs with preview deployment URLs
• Removes previous preview comments when updated
• Uses customizable templates for comment formatting

Designed to run within Kuberntes Pods to provide stakeholders with easy access to deployment previews for each PR.

Demo

Quickstart

Running locally

# Set required environment variables
export PR_NUMBER="123"
export USER_LOGIN="github-user"
export COMMIT_SHA="abc123def456"
export URL="https://preview-domain.example.com"
export GITHUB_TOKEN="ghp_yourtokenhere"

# Run the application
go run main.go your-org/your-repo

Kubernetes Integration Example

---
apiVersion: batch/v1
kind: Job
metadata:
  name: some-important-task
spec:
  template:
    spec:
      containers:
        - command:
            - sh
            - "-c"
            - echo hello world
          image: busybox:1
          name: busybox
          resources: {}
      initContainers:
        - args:
            # repo in the format owner/repo
            - meysam81/preview-bot
          env:
            # github username
            - name: USER_LOGIN
              value: meysam81
            - name: GITHUB_TOKEN
              value: ghp_yourtokenhere
            - name: COMMIT_SHA
              value: abc123def456
            - name: PR_NUMBER
              value: "123"
            - name: URL
              value: https://pr123.example.com
          image: ghcr.io/meysam81/preview-bot
          name: preview-bot
          resources:
            limits:
              cpu: 10m
              memory: 10Mi
            requests:
              cpu: 10m
              memory: 10Mi
          securityContext:
            allowPrivilegeEscalation: false
            capabilities:
              drop:
                - ALL
            readOnlyRootFilesystem: true
            runAsGroup: 65534
            runAsNonRoot: true
            runAsUser: 65534
          terminationMessagePolicy: FallbackToLogsOnError
      restartPolicy: OnFailure

Environment Variables

Variable	Description	Default
PR_NUMBER	Pull request number	Required
USER_LOGIN	GitHub username for the bot	Required
COMMIT_SHA	Commit SHA being deployed	Required
URL	Deployment preview URL	Required
GITHUB_TOKEN	GitHub API token with repo permissions	Required
TITLE	Comment title	# Preview Deployment
ASSETS_DIR	Directory for template files	/
DEBUG	Enable debug logging	false

Template

Create a file named preview-body.md.tpl in your assets directory with available variables:

• {{TITLE}}: The comment title
• {{COMMIT_SHA}}: The commit SHA
• {{URL}}: The deployment URL