Ghaymah SRE exam submission - Mohamed Adel

q1-deploy-monitor/health-check.sh

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+#!/usr/bin/env bash
+#
+# health-check.sh
+# Polls the app's /health endpoint every 30 seconds, logs status + response
+# time to a CSV file that the dashboard (dashboard.html) can read, and
+# alerts (stderr + log) if the app is unhealthy for 3 consecutive checks.
+#
+# Usage:
+#   ./health-check.sh https://your-app.ghaymah.systems
+#
+# Run in the background on the host, or as a sidecar container, or as a
+# systemd service (recommended for production on Ghaymah).
+
+set -uo pipefail
+
+APP_URL="${1:-http://localhost:8080}"
+HEALTH_ENDPOINT="${APP_URL%/}/health"
+CHECK_INTERVAL=30          # seconds
+LOG_FILE="./metrics.csv"
+FAIL_THRESHOLD=3
+consecutive_failures=0
+
+# Create CSV header if the file doesn't exist yet
+if [[ ! -f "$LOG_FILE" ]]; then
+    echo "timestamp,status,http_code,response_time_ms" > "$LOG_FILE"
+fi
+
+log() {
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1"
+}
+
+log "Starting health monitor for: $HEALTH_ENDPOINT (interval: ${CHECK_INTERVAL}s)"
+
+while true; do
+    start_ms=$(date +%s%3N)
+
+    # -o /dev/null discards body, -w prints http_code, -s silent, -m 5 timeout 5s
+    http_code=$(curl -s -o /dev/null -w "%{http_code}" -m 5 "$HEALTH_ENDPOINT")
+    curl_exit=$?
+
+    end_ms=$(date +%s%3N)
+    response_time_ms=$((end_ms - start_ms))
+    timestamp=$(date '+%Y-%m-%d %H:%M:%S')
+
+    if [[ $curl_exit -eq 0 && "$http_code" == "200" ]]; then
+        status="UP"
+        consecutive_failures=0
+        log "OK  - ${HEALTH_ENDPOINT} - ${http_code} - ${response_time_ms}ms"
+    else
+        status="DOWN"
+        consecutive_failures=$((consecutive_failures + 1))
+        log "FAIL - ${HEALTH_ENDPOINT} - http_code=${http_code:-none} curl_exit=${curl_exit} - failure #${consecutive_failures}"
+
+        if [[ $consecutive_failures -ge $FAIL_THRESHOLD ]]; then
+            log "ALERT: ${consecutive_failures} consecutive failures! Application appears DOWN." >&2
+            # In production: send this to Slack/Email/PagerDuty/Ghaymah alerting webhook, e.g.:
+            # curl -s -X POST -H "Content-Type: application/json" \
+            #   -d "{\"text\":\"ALERT: ${APP_URL} is down (${consecutive_failures} consecutive failures)\"}" \
+            #   "$ALERT_WEBHOOK_URL"
+        fi
+    fi
+
+    echo "${timestamp},${status},${http_code:-0},${response_time_ms}" >> "$LOG_FILE"
+
+    sleep "$CHECK_INTERVAL"
+done