Service Health Check Script with Notifications

Beginner10 min

Build a bash script that monitors service endpoints, checks response codes and latency, and sends alerts when services are down.

Prerequisites

-Bash and curl installed
-Services or URLs to monitor

Steps

Check a single endpoint

Use curl to verify a service returns HTTP 200 and measure response time.

$ curl -s -o /dev/null -w '%{http_code} %{time_total}s' http://localhost:3000/health

-s silences progress, -o /dev/null discards body, -w prints status code and timing.

Create a multi-service health check script

Loop through a list of endpoints and check each one.

$ cat > healthcheck.sh << 'EOF' #!/usr/bin/env bash set -euo pipefail ENDPOINTS=( "http://localhost:3000/health" "http://localhost:3001/api/health" "https://api.example.com/status" ) for url in "${ENDPOINTS[@]}"; do HTTP_CODE=$(curl -s -o /dev/null -w '%{http_code}' --max-time 5 "$url" || echo "000") if [[ "$HTTP_CODE" -eq 200 ]]; then echo "[OK] $url ($HTTP_CODE)" else echo "[FAIL] $url ($HTTP_CODE)" >&2 fi done EOF chmod +x healthcheck.sh

Add response time monitoring

Track response times and flag slow endpoints above a threshold.

$ echo 'RESPONSE_TIME=$(curl -s -o /dev/null -w "%{time_total}" --max-time 10 "$url")' && echo 'if (( $(echo "$RESPONSE_TIME > 2.0" | bc -l) )); then echo "[SLOW] $url (${RESPONSE_TIME}s)"; fi'

Add webhook notification on failure

Send an alert to Slack or Discord when a health check fails.

$ echo 'curl -s -X POST -H "Content-Type: application/json" -d "{\"text\": \"ALERT: $url returned $HTTP_CODE\"}" "$WEBHOOK_URL"'

Store webhook URLs in environment variables, not in the script. Never commit secrets to version control.

Full Script

full-script.sh

#!/usr/bin/env bash
set -euo pipefail

# Service Health Checker
ENDPOINTS=(
  "http://localhost:3000/health"
  "http://localhost:3001/api/health"
)

TIMEOUT=5
SLOW_THRESHOLD=2.0
WEBHOOK_URL="${SLACK_WEBHOOK:-}"
FAILURES=0

log() { echo "[$(date +'%H:%M:%S')] $*"; }

for url in "${ENDPOINTS[@]}"; do
  RESPONSE=$(curl -s -o /dev/null -w '%{http_code} %{time_total}' --max-time "$TIMEOUT" "$url" 2>/dev/null || echo "000 0")
  HTTP_CODE=$(echo "$RESPONSE" | awk '{print $1}')
  DURATION=$(echo "$RESPONSE" | awk '{print $2}')

  if [[ "$HTTP_CODE" -eq 200 ]]; then
    log "[OK]   $url (${DURATION}s)"
  else
    log "[FAIL] $url (HTTP $HTTP_CODE)" >&2
    ((FAILURES++))
    if [[ -n "$WEBHOOK_URL" ]]; then
      curl -s -X POST -H 'Content-Type: application/json' \
        -d "{"text": "ALERT: $url returned HTTP $HTTP_CODE"}" \
        "$WEBHOOK_URL" > /dev/null
    fi
  fi
done

if [[ $FAILURES -gt 0 ]]; then
  log "$FAILURES service(s) failing"
  exit 1
fi
log "All services healthy"

FAQ

Discussion

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#!/usr/bin/env bash set -euo pipefail # Service Health Checker ENDPOINTS=( "http://localhost:3000/health" "http://localhost:3001/api/health" ) TIMEOUT=5 SLOW_THRESHOLD=2.0 WEBHOOK_URL="${SLACK_WEBHOOK:-}" FAILURES=0 log() { echo "[$(date +'%H:%M:%S')] $*"; } for url in "${ENDPOINTS[@]}"; do RESPONSE=$(curl -s -o /dev/null -w '%{http_code} %{time_total}' --max-time "$TIMEOUT" "$url" 2>/dev/null || echo "000 0") HTTP_CODE=$(echo "$RESPONSE" | awk '{print $1}') DURATION=$(echo "$RESPONSE" | awk '{print $2}') if [[ "$HTTP_CODE" -eq 200 ]]; then log "[OK] $url (${DURATION}s)" else log "[FAIL] $url (HTTP $HTTP_CODE)" >&2 ((FAILURES++)) if [[ -n "$WEBHOOK_URL" ]]; then curl -s -X POST -H 'Content-Type: application/json' \ -d "{"text": "ALERT: $url returned HTTP $HTTP_CODE"}" \ "$WEBHOOK_URL" > /dev/null fi fi done if [[ $FAILURES -gt 0 ]]; then log "$FAILURES service(s) failing" exit 1 fi log "All services healthy"