version: 1
id: monitoring-basics
title: Build a Tiny Uptime Check
summary: Turn raw probe results into an up/down status file — a 90Days monitoring fundamentals drill.
difficulty: beginner
estimatedMinutes: 25
prerequisites: [networking-basics]
image: alpine:3.21
shell: /bin/sh
setup:
  - "mkdir -p /workspace/monitor"
  - "printf 'payments 200\\ncheckout 500\\n' > /workspace/monitor/probes.txt"
tasks:
  - id: uptime-status
    title: Summarize probe health
    description: 'Create executable /workspace/monitor/check.sh that reads probes.txt and writes /workspace/monitor/status.env with payments=up and checkout=down (HTTP 2xx = up, otherwise down). Run the script once. Also write /workspace/monitor/ALERT.md mentioning checkout.'
    hints:
      - '200 means up; 500 means down'
      - status.env should contain payments=up and checkout=down
      - ALERT.md should call out the failing checkout probe.
    checks:
      - type: command
        name: Checker is executable
        command: test -x /workspace/monitor/check.sh
      - type: file
        name: Payments up
        path: /workspace/monitor/status.env
        value: payments=up
      - type: file
        name: Checkout down
        path: /workspace/monitor/status.env
        value: checkout=down
      - type: file
        name: Alert mentions checkout
        path: /workspace/monitor/ALERT.md
        value: checkout
limits: {cpus: "0.5", memory: 128m, pids: 64, timeout: 1800, network: false}
attribution: "Adapted from 90DaysOfDevOps monitoring/observability topics (Michael Cade, CC BY-NC-SA 4.0). Rewritten as an interactive PlatformForge scenario."