Health Checks

Simple Health Endpoint

Python

@app.route('/health')
def health():
    return {'status': 'healthy'}, 200

Node.js

app.get('/health', (req, res) => {
    res.json({ status: 'healthy' });
});

Go

http.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
    w.WriteHeader(http.StatusOK)
    w.Write([]byte(`{"status":"healthy"}`))
})

Docker Health Check

Dockerfile

HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
    CMD curl -f http://localhost:8000/health || exit 1

docker-compose.yml

services:
  snapcode:
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
      interval: 30s
      timeout: 3s
      retries: 3
      start_period: 5s

# Check health status
docker inspect --format='{{.State.Health.Status}}' snapcode

Nginx Health Check

location /health {
    access_log off;
    return 200 "healthy\n";
    add_header Content-Type text/plain;
}

Load Balancer Health Checks

HAProxy

backend snapcode_backend
    option httpchk GET /health
    http-check expect status 200
    server app1 localhost:8000 check

Nginx Upstream

upstream backend {
    server localhost:8000 max_fails=3 fail_timeout=30s;
    server localhost:8001 max_fails=3 fail_timeout=30s;
}

Monitoring Script

health-check.sh

#!/bin/bash
URL="http://localhost:8000/health"
RESPONSE=$(curl -s -o /dev/null -w "%{http_code}" $URL)

if [ $RESPONSE -ne 200 ]; then
    echo "Service unhealthy: $RESPONSE"
    # Send alert
    systemctl restart snapcode
fi

Cron:

* * * * * /path/to/health-check.sh

Comprehensive Health Check

@app.route('/health')
def health():
    checks = {
        'database': check_db(),
        'cache': check_redis(),
        'disk': check_disk_space(),
    }

    status = 'healthy' if all(checks.values()) else 'unhealthy'
    code = 200 if status == 'healthy' else 503

    return {'status': status, 'checks': checks}, code