Health

Monitor system health, services, and uptime.

Setup

API keys (optional; for UptimeRobot, Healthchecks.io, Slack, Resend; store in vault, never use export):

•UptimeRobot: vault_save uptimerobot_key "xxx"
•Healthchecks.io: vault_save healthchecks_uuid "xxx"
•Slack webhook: vault_save slack_webhook_url "xxx"
•Resend: vault_save resend_api_key "xxx"
•Keys auto-inject as uppercase env vars.

curl, jq, nc, openssl are usually pre-installed. For systemd/Docker checks, those tools must be available.

HTTP Health Checks

bash

# Basic health check
curl -s -o /dev/null -w "%{http_code}" https://example.com

# With response time
curl -s -o /dev/null -w "HTTP: %{http_code}, Time: %{time_total}s\n" https://example.com

# Check multiple endpoints
for url in "https://api.example.com/health" "https://app.example.com"; do
  status=$(curl -s -o /dev/null -w "%{http_code}" "$url")
  echo "$url: $status"
done

# Detailed check
curl -s -w "\n\nDNS: %{time_namelookup}s\nConnect: %{time_connect}s\nTTFB: %{time_starttransfer}s\nTotal: %{time_total}s\nHTTP: %{http_code}\n" -o /dev/null https://example.com

Service Monitoring

bash

# Check if port is open
nc -zv example.com 443

# Check with timeout
timeout 5 bash -c "echo > /dev/tcp/example.com/443" && echo "UP" || echo "DOWN"

# Check systemd service
systemctl is-active nginx

# Check service status
systemctl status nginx --no-pager

# Check Docker container
docker inspect -f '{{.State.Status}}' container_name

System Health

bash

# CPU usage
top -bn1 | grep "Cpu(s)" | awk '{print $2}' | cut -d'%' -f1

# Memory usage
free -h

# Disk usage
df -h

# Load average
uptime

# Check running processes
ps aux --sort=-%mem | head -10

# Check open files
lsof | wc -l

# Network connections
netstat -an | grep ESTABLISHED | wc -l

SSL Certificate Check

bash

# Check expiration
echo | openssl s_client -connect example.com:443 2>/dev/null | openssl x509 -noout -dates

# Days until expiration
echo | openssl s_client -connect example.com:443 2>/dev/null | openssl x509 -noout -enddate | cut -d= -f2 | xargs -I {} date -d {} +%s | xargs -I {} echo $(( ({} - $(date +%s)) / 86400 )) days

# Certificate info
echo | openssl s_client -connect example.com:443 2>/dev/null | openssl x509 -noout -text | grep -E "Issuer:|Subject:|DNS:"

Uptime Monitoring

UptimeRobot API

bash

# Get monitors
curl -s -X POST "https://api.uptimerobot.com/v2/getMonitors" \
  -H "Cache-Control: no-cache" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "api_key=$UPTIMEROBOT_KEY&format=json" | jq '.monitors[]'

# Create monitor
curl -s -X POST "https://api.uptimerobot.com/v2/newMonitor" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "api_key=$UPTIMEROBOT_KEY&friendly_name=MySite&url=https://example.com&type=1" | jq '.'

# Get uptime
curl -s -X POST "https://api.uptimerobot.com/v2/getMonitors" \
  -d "api_key=$UPTIMEROBOT_KEY&monitors=MONITOR_ID&custom_uptime_ratios=30" | jq '.monitors[0].custom_uptime_ratio'

Healthchecks.io

bash

# Ping (mark as alive)
curl -s "https://hc-ping.com/$HEALTHCHECKS_UUID"

# Report failure
curl -s "https://hc-ping.com/$HEALTHCHECKS_UUID/fail"

# Report start
curl -s "https://hc-ping.com/$HEALTHCHECKS_UUID/start"

# With execution time
curl -s "https://hc-ping.com/$HEALTHCHECKS_UUID/$?rid=$(uuidgen)"

Alerting

Slack Alert

bash

send_alert() {
  local message="$1"
  curl -s -X POST "$SLACK_WEBHOOK_URL" \
    -H "Content-Type: application/json" \
    -d "{\"text\": \"🚨 Health Alert: $message\"}"
}

# Usage
curl -s -o /dev/null -w "%{http_code}" https://example.com | grep -v "200\|301\|302" && send_alert "Site down!"

Email Alert

bash

send_email() {
  local subject="$1"
  local body="$2"
  curl -s -X POST "https://api.resend.com/emails" \
    -H "Authorization: Bearer $RESEND_API_KEY" \
    -H "Content-Type: application/json" \
    -d "{\"from\": \"alerts@example.com\", \"to\": \"admin@example.com\", \"subject\": \"$subject\", \"text\": \"$body\"}"
}

Monitoring Script

bash

#!/bin/bash
# health_check.sh

check_url() {
  local url=$1
  local status=$(curl -s -o /dev/null -w "%{http_code}" --max-time 10 "$url")
  if [[ "$status" =~ ^2[0-9][0-9]$ ]]; then
    echo "✅ $url - OK ($status)"
  else
    echo "❌ $url - FAIL ($status)"
    # Send alert here
  fi
}

check_url "https://example.com"
check_url "https://api.example.com/health"

Tips

•Set appropriate timeouts for checks
•Check from multiple locations if possible
•Monitor response time, not just status
•Set up alerts for certificate expiration
•Log check results for trend analysis

Triggers

health check, uptime, monitor, status check, service health, ssl check, system monitoring, health monitoring