Bash Scripting for DevOps: 20 Scripts That Automate Everything

#!/usr/bin/env bash
set -euo pipefail
# -e: exit on any error
# -u: treat unset variables as errors
# -o pipefail: if any command in a pipeline fails, the pipeline fails
# Together these prevent scripts from continuing past errors silently

# Also useful for debugging:
# set -x    # Print each command before executing
# trap 'echo "Error on line $LINENO"' ERR  # More specific error info

#!/usr/bin/env bash
# scripts/health-check.sh — Check multiple services, alert on failure
set -euo pipefail

SERVICES=(
  "web:https://myapp.com/health:200"
  "api:https://api.myapp.com/health:200"
  "docs:https://docs.myapp.com/:200"
)
ALERT_EMAIL="${ALERT_EMAIL:[email protected]}"
SLACK_WEBHOOK="${SLACK_WEBHOOK:-}"
TIMEOUT=10
FAILED=0

check_service() {
  local name="$1" url="$2" expected_code="$3"
  local actual_code
  actual_code=$(curl -s -o /dev/null -w "%{http_code}" --max-time "$TIMEOUT" "$url" 2>/dev/null || echo "000")

  if [[ "$actual_code" == "$expected_code" ]]; then
    echo "  [OK]   $name ($url) → $actual_code"
    return 0
  else
    echo "  [FAIL] $name ($url) → expected $expected_code, got $actual_code"
    return 1
  fi
}

send_alert() {
  local message="$1"
  echo "$message"

  if [[ -n "$SLACK_WEBHOOK" ]]; then
    curl -s -X POST "$SLACK_WEBHOOK"       -H 'Content-type: application/json'       -d "{"text": "🚨 Health Check Failure\n$message"}"       > /dev/null
  fi
}

echo "Health check — $(date -u '+%Y-%m-%d %H:%M:%S UTC')"

for service_def in "${SERVICES[@]}"; do
  IFS=':' read -r name url expected <<< "$service_def"
  # url may contain :// so we reconstruct it
  url="${service_def#${name}:}"
  url="${url%:${expected}}"

  if ! check_service "$name" "$url" "$expected"; then
    FAILED=$((FAILED + 1))
    send_alert "Service '$name' is DOWN. URL: $url — got $(curl -s -o /dev/null -w '%{http_code}' "$url" 2>/dev/null || echo 000)"
  fi
done

echo ""
if [[ $FAILED -eq 0 ]]; then
  echo "All services healthy."
  exit 0
else
  echo "$FAILED service(s) FAILED."
  exit 1
fi