A tiny web application Golang showcases best practices of running microservices in Kubernetes

golang kubernetes microservices

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

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