Podinfo is a tiny web application made with Go that showcases the best practices of running microservices in Kubernetes. Podinfo is used by CNCF projects like Flux and Flagger for end-to-end testing and workshops.

Golang Project Specifications

• Health checks (readiness and liveness)
• Graceful shutdown on interrupt signals
• File watcher for secrets and configmaps
• Structured logging with zap
• 12-factor app with viper
• Fault injection (random errors and latency)
• Instrumented with Prometheus and Open Telemetry
• Swagger docs
• CUE, Helm and Kustomize installers
• End-to-End testing with Kubernetes Kind and Helm
• Kustomize testing with GitHub Actions and Open Policy Agent
• Multi-arch container image with Docker buildx and Github Actions
• Container image signing with Sigstore cosign
• CVE scanning with Trivy

Go 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
• 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 /healthz used by Kubernetes liveness probe
• GET /readyz used by Kubernetes readiness probe
• 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/PUT /cache/{key} saves the posted content to Redis
• GET /cache/{key} returns the content from Redis if the key exists
• DELETE /cache/{key} deletes the key from Redis if exists
• 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
• GET /swagger.json returns the API Swagger docs, used for Linkerd service profiling and Gloo routes discovery

Golang gRPC API

• /grpc.health.v1.Health/Check health checking