echo-service

Tiny Go HTTP server that simply echoes the request it receives. May be useful for debugging clients, load‑balancers, or service meshes.

Background reading

• Writing Web Applications in the Go documentation
• An Introduction to Handlers and Servemuxes in Go by Alex Edwards

TODOs

• Enforce a minimum test coverage
• More logging in ./cmd/echo-service/main.go
• Integration tests (run server and test the endpoints)
• End-to-end Kubernetes tests
• Prometheus counters and a /metrics endpoint
• Container signing and hardening

Requirements

Requirements vary depending on how you want to use this.

• jq for pretty-printing JSON output (optional)
• Go 1.22+ (only for go run / local builds)
• Docker 20+ (only for the container demo)
• kubectl and a cluster (for the Kubernetes section)
• Optionally, minikube (for the Kubernetes section)

Usage

Quick start (run from source)

go run ./cmd/echo-service
# In another terminal:
curl -s http://localhost:8080/hello | jq .

Docker usage (with Docker, no K8s)

From the repository root, run:

docker build -t echo-service:0.1.0 .
docker run --rm -p 8080:8080 echo-service:0.1.0

Then in another terminal instance, run:

curl -s http://localhost:8080/hello | jq .

and you should get

{
  "method": "GET",
  "path": "/hello",
  "headers": {
    "Accept": [
      "*/*"
    ],
    "User-Agent": [
      "curl/8.12.1"
    ]
  },
  "host": "localhost:8080",
  "remote_addr": "[::1]:65325"
}

Kubernetes usage

For a dev environment only, start by building and loading the image locally.

# Point Docker to Minikube’s daemon
eval "$(minikube -p minikube docker-env)"

# Build the :dev tag referenced by the dev overlay
docker build -t ghcr.io/gmarmstrong/echo-service:dev .

Now, regardless of environment, do the rollout:

kubectl rollout status deployment/echo-service

We can now verify that the rollout was successful:

kubectl port-forward svc/echo-service 8080:80 &
curl -s http://localhost:8080/hello | jq .

Endpoints

Path	Method	Purpose	Typical response
/{any}	GET	Echo request back as JSON	200 application/json
/healthz	GET	Liveness/readiness probe	204 No Content

The service listens on PORT (default 8080).
You can override it by setting that environment variable using kubectl or by editing k8s/deployment.yaml:

env:
  - name: PORT
    value: "9090"
ports:
  - containerPort: 9090
readinessProbe:
  httpGet:
    path: /healthz
    port: 9090
livenessProbe:
  httpGet:
    path: /healthz
    port: 9090

Development & CI

CI flow

The Build container image workflow (.github/workflows/build-image.yml) runs on every push to main (and on tag pushes). It:

1. Builds a multi‑arch Docker image with Buildx
2. Tags it based on the Git ref (v0.x.y, sha‑<digest>)
3. Pushes the image to GHCR

Local testing

# Static analysis
go vet ./...

# Unit tests
go test ./... -v

# Check that the image builds and runs
docker build -t echo-service:dev .
docker run --rm -p 8080:8080 echo-service:dev

License

This project uses the MIT license. See LICENSE for the full text.