Q: Your product and QA teams are bottlenecked by shared staging environments. Merging untested frontend and backend changes to the shared `dev` cluster causes frequent regressions. The engineering lead wants an automated ephemeral environment created for every open pull request (e.g., `https://pr-412.preview.example.com`). The environment must spin up within 3 minutes, deploy full backend microservices with isolated database schemas, and automatically tear down immediately when the PR is merged or closed to eliminate cloud cost waste.
Build fully automated on-demand ephemeral preview environments for every pull request using Argo CD ApplicationSets, PR generators, dynamic DNS wildcards, and automated resource cleanup on PR closure.
Want to master this scenario in a live sandbox? KodeKloud's Enterprise GitOps with ArgoCD & Kubernetes Rollouts covers this exact problem with hands-on terminal drills.
🛠️ Production Runbook & Step-by-Step Resolution
Configure Argo CD ApplicationSet with Pull Request Generator
Deploy an Argo CD `ApplicationSet` using the GitHub Pull Request Generator. The generator continuously polls or receives webhooks from the GitHub API, filtering for active PRs with the label `preview-env`.
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
name: pr-preview-environments
namespace: argocd
spec:
generators:
- pullRequest:
github:
owner: myorg
repo: e-commerce-app
labels:
- preview-env
tokenRef:
secretName: github-pr-token
key: token
requeueAfterSeconds: 60
template:
metadata:
name: 'preview-pr-{{number}}'
spec:
project: default
source:
repoURL: 'https://github.com/myorg/e-commerce-app.git'
targetRevision: '{{head_sha}}'
path: helm/app
helm:
valuesObject:
ingress:
host: 'pr-{{number}}.preview.example.com'
database:
schema: 'pr_{{number}}'
destination:
server: 'https://kubernetes.default.svc'
namespace: 'preview-pr-{{number}}'
syncPolicy:
automated:
prune: true
selfHeal: true
syncOptions:
- CreateNamespace=trueImplement Dynamic Wildcard Ingress and Cert-Manager DNS-01
Set up an AWS Route53 or Cloudflare wildcard DNS record `*.preview.example.com` pointing to the cluster Ingress Controller load balancer. Use `cert-manager` with Let's Encrypt DNS-01 challenge to issue a single wildcard SSL certificate `*.preview.example.com`, eliminating per-PR Let's Encrypt rate limits.
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
name: wildcard-preview-cert
namespace: ingress-nginx
spec:
secretName: wildcard-preview-tls
issuerRef:
name: letsencrypt-route53-dns
kind: ClusterIssuer
dnsNames:
- '*.preview.example.com'Automate Ephemeral Database Provisioning and Seeding
Add a Helm `pre-install` hook Job that connects to a dedicated PostgreSQL preview cluster, executes `CREATE DATABASE pr_412 TEMPLATE staging_seed;`, and runs initial database migrations. Add a `post-delete` hook that drops the ephemeral database when the Helm release is uninstalled.
Configure Automated Teardown and GitHub PR Commenting
When a developer closes or merges the PR, the Argo CD PR Generator detects the closed PR state and automatically deletes the corresponding `Application` resource. With cascade deletion enabled (`prune: true`), Argo CD tears down the namespace, pods, ingress, and PVs immediately.
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