podinfo

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

Specifications:

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

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
• POST /fault_injection/enable makes this instance respond with HTTP 500 to all application endpoints (probes, metrics, pprof and the /fault_injection/* control endpoints stay healthy) — useful for testing client-side circuit breakers / outlier detection against a single "sick" replica
• POST /fault_injection/disable restores normal responses
• GET /fault_injection/status returns the current fault injection state (enabled or disabled)
• 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

gRPC API:

• /grpc.health.v1.Health/Check health checking
• /grpc.EchoService/Echo echos the received content
• /grpc.VersionService/Version returns podinfo version and Git commit hash
• /grpc.DelayService/Delay returns a successful response after the given seconds in the body of gRPC request
• /grpc.EnvService/Env returns environment variables as a JSON array
• /grpc.HeaderService/Header returns the headers present in the gRPC request. Any custom header can also be given as a part of request and that can be returned using this API
• /grpc.InfoService/Info returns the runtime information
• /grpc.PanicService/Panic crashes the process with gRPC status code as '1 CANCELLED'
• /grpc.StatusService/Status returns the gRPC Status code given in the request body
• /grpc.TokenService/TokenGenerate issues a JWT token valid for one minute
• /grpc.TokenService/TokenValidate validates the JWT token

Web UI:

To access the Swagger UI open <podinfo-host>/swagger/index.html in a browser.

Guides

• Getting started with Timoni
• Getting started with Flux
• Progressive Deliver with Flagger and Linkerd
• Automated canary deployments with Kubernetes Gateway API

Install

To install Podinfo on Kubernetes the minimum required version is Kubernetes v1.23.

Timoni

Install with Timoni:

timoni -n default apply podinfo oci://ghcr.io/stefanprodan/modules/podinfo

Helm

Install from github.io:

helm repo add podinfo https://stefanprodan.github.io/podinfo

helm upgrade --install --wait frontend \
--namespace test \
--set replicaCount=2 \
--set backend=http://backend-podinfo:9898/echo \
podinfo/podinfo

helm test frontend --namespace test

helm upgrade --install --wait backend \
--namespace test \
--set redis.enabled=true \
podinfo/podinfo

Install from ghcr.io:

helm upgrade --install --wait podinfo --namespace default \
oci://ghcr.io/stefanprodan/charts/podinfo

Kustomize

kubectl apply -k github.com/stefanprodan/podinfo//kustomize

Docker

docker run -dp 9898:9898 stefanprodan/podinfo

Continuous Delivery

In order to install podinfo on a Kubernetes cluster and keep it up to date with the latest release in an automated manner, you can use Flux.

Install the Flux CLI on MacOS and Linux using Homebrew:

brew install fluxcd/tap/flux

Install the Flux controllers needed for Helm operations:

flux install \
--namespace=flux-system \
--network-policy=false \
--components=source-controller,helm-controller

Add podinfo's Helm repository to your cluster and configure Flux to check for new chart releases every ten minutes:

flux create source helm podinfo \
--namespace=default \
--url=https://stefanprodan.github.io/podinfo \
--interval=10m

Create a podinfo-values.yaml file locally:

cat > podinfo-values.yaml <<EOL
replicaCount: 2
resources:
  limits:
    memory: 256Mi
  requests:
    cpu: 100m
    memory: 64Mi
EOL

Create a Helm release for deploying podinfo in the default namespace:

flux create helmrelease podinfo \
--namespace=default \
--source=HelmRepository/podinfo \
--release-name=podinfo \
--chart=podinfo \
--chart-version=">5.0.0" \
--values=podinfo-values.yaml

Based on the above definition, Flux will upgrade the release automatically when a new version of podinfo is released. If the upgrade fails, Flux can rollback to the previous working version.

You can check what version is currently deployed with:

flux get helmreleases -n default

To delete podinfo's Helm repository and release from your cluster run:

flux -n default delete source helm podinfo
flux -n default delete helmrelease podinfo

If you wish to manage the lifecycle of your applications in a GitOps manner, check out this workflow example for multi-env deployments with Flux, Kustomize and Helm.