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k8s-podinfo

Podinfo is a tiny web application made with Go that showcases best practices of running microservices in Kubernetes.

Specifications:

• Release automation (Make/TravisCI/CircleCI/Quay.io/Google Cloud Container Builder/Skaffold/Weave Flux)
• Multi-platform Docker image (amd64/arm/arm64/ppc64le/s390x)
• Health checks (readiness and liveness)
• Graceful shutdown on interrupt signals
• File watcher for secrets and configmaps
• Instrumented with Prometheus
• Tracing with Istio and Jaeger
• Structured logging with zap
• 12-factor app with viper
• Fault injection (random errors and latency)
• Helm chart

Web API:

• GET / prints runtime information
• GET /version prints podinfo version and git commit hash
• GET /metrics return HTTP requests duration and Go runtime metrics
• GET /healthz used by Kubernetes liveness probe
• GET /readyz used by Kubernetes readiness probe
• POST /readyz/enable signals the Kubernetes LB that this instance is ready to receive traffic
• POST /readyz/disable signals the Kubernetes LB to stop sending requests to this instance
• GET /status/{code} returns the status code
• GET /panic crashes the process with exit code 255
• POST /echo forwards the call to the backend service and echos the posted content
• GET /env returns the environment variables as a JSON array
• GET /headers returns a JSON with the request HTTP headers
• GET /delay/{seconds} waits for the specified period
• POST /token issues a JWT token valid for one minute JWT=$(curl -sd 'anon' podinfo:9898/token | jq -r .token)
• GET /token/validate validates the JWT token curl -H "Authorization: Bearer $JWT" podinfo:9898/token/validate
• GET /configs returns a JSON with configmaps and/or secrets mounted in the config volume
• POST /store writes the posted content to disk at /data/hash and returns the SHA1 hash of the content
• GET /store/{hash} returns the content of the file /data/hash if exists
• GET /ws/echo echos content via websockets podcli ws ws://localhost:9898/ws/echo
• GET /chunked/{seconds} uses transfer-encoding type chunked to give a partial response and then waits for the specified period

Guides

• Deploy and upgrade with Helm
• Horizontal Pod Auto-scaling
• Monitoring and alerting with Prometheus
• StatefulSets with local persistent volumes
• Expose Kubernetes services over HTTPS with Ngrok
• A/B Testing with Ambassador API Gateway
• Canary Deployments with Istio
• GitHub Actions CI demo