Servlets · Lesson 12

Servlet Best Practices and Deployment

Preparing a Servlet Application

Production servlet applications need more than working request handlers. Deployment readiness includes configuration, observability, security, resource limits, and a repeatable way to package the application. A servlet container such as Tomcat supplies the runtime, but the application still owns its behavior.

A Small Health Endpoint

A health endpoint should be fast and report whether the application process can serve requests. Keep deep dependency checks in a separate readiness check so an unavailable downstream service does not make every liveness probe fail.

import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;

public class HealthServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws IOException {
        response.setContentType("application/json;charset=UTF-8");
        response.setStatus(HttpServletResponse.SC_OK);
        response.getWriter().println("{\"status\":\"UP\"}");
    }
}

Deployment Concerns

Common Mistake and Practices

Common Mistake: Treating a successful local deployment as proof that production is ready. Production traffic exposes missing timeouts, unbounded sessions, weak logging, and configuration assumptions that local tests may not cover.

• Externalize environment-specific configuration.
• Use connection and request timeouts.
• Centralize error handling and logging.
• Set session and upload limits.
• Test the packaged artifact in a production-like container.

Real-World Use Case

A team packages a servlet application as a WAR, deploys it to a managed Tomcat cluster, and uses health checks for rollout decisions. Configuration comes from the deployment environment, while logs and metrics flow to a central observability system.