version: 1
id: http-json-api
title: Build a Tiny JSON API in Go
summary: Extend HTTP skills with a /payments endpoint that returns JSON and a content-type header.
difficulty: intermediate
estimatedMinutes: 40
prerequisites: [http-health-server]
image: golang:1.22-alpine
shell: /bin/sh
setup:
  - "apk add --no-cache wget iproute2 >/dev/null"
  - "mkdir -p /workspace"
tasks:
  - id: payments-api
    title: Serve JSON payments
    description: 'Write /workspace/main.go that listens on :8080, keeps /health returning ok, and adds GET /payments returning JSON [{"id":1,"amount":25}] with Content-Type application/json. Run it in the background.'
    hints:
      - encoding/json or a raw JSON string both work.
      - Set Header Content-Type to application/json before Write.
      - Keep /health working for probes.
    checks:
      - type: file
        name: Payments route present
        path: /workspace/main.go
        value: "/payments"
      - type: file
        name: Content-Type set
        path: /workspace/main.go
        value: application/json
      - type: port
        name: Port 8080 listening
        port: 8080
      - type: command
        name: Health still ok
        command: "wget -qO- http://127.0.0.1:8080/health | grep -q ok"
      - type: command
        name: Payments JSON body
        command: "wget -qO- http://127.0.0.1:8080/payments | grep -q '\"amount\":25'"
      - type: command
        name: JSON content type
        command: "wget -S -qO- http://127.0.0.1:8080/payments 2>&1 | grep -qi 'content-type: application/json'"
limits: {cpus: "1.0", memory: 512m, pids: 128, timeout: 1800, network: true}