How to Create a Liveness Probe HTTP Mock in Python

Build a lightweight HTTP server in Python that mimics a Kubernetes-style liveness endpoint, returning JSON health status for local testing.

Easy Python 3.9+ Aug 9, 2026 Production deployment patterns 15 views 0 copies

http healthcheck mock-server testing liveness

Python code

37 lines

Python 3.9+

import http.server
import threading
import time


class LivenessHandler(http.server.BaseHTTPRequestHandler):
    def do_GET(self):
        if self.path == "/healthz":
            self.send_response(200)
            self.send_header("Content-Type", "application/json")
            self.end_headers()
            self.wfile.write(b'{"status": "alive"}')
        else:
            self.send_response(404)
            self.end_headers()
            self.wfile.write(b'{"status": "not found"}')


def start_mock_server(port=8080):
    server = http.server.HTTPServer(("127.0.0.1", port), LivenessHandler)
    thread = threading.Thread(target=server.serve_forever, daemon=True)
    thread.start()
    return server


if __name__ == "__main__":
    mock = start_mock_server(port=8080)
    print(f"Mock liveness probe running on http://127.0.0.1:8080/healthz")

    time.sleep(0.2)
    try:
        from urllib.request import urlopen
        response = urlopen("http://127.0.0.1:8080/healthz")
        print(f"Response status: {response.status}")
        print(f"Response body: {response.read().decode()}")
    finally:
        mock.shutdown()

Output

stdout

Mock liveness probe running on http://127.0.0.1:8080/healthz
Response status: 200
Response body: {"status": "alive"}

How it works

The http.server module provides a simple HTTP server that runs a custom BaseHTTPRequestHandler subclass. The do_GET method controls behavior for GET requests, returning a 200 with JSON for /healthz and 404 otherwise. Running the server in a daemon thread lets the main program continue execution, and urlopen verifies the endpoint works before shutting down.

Common mistakes

Forgetting to send `end_headers()` before writing the response body
Using `HTTPServer` directly instead of subclassing `BaseHTTPRequestHandler`
Not calling `shutdown()` which can leave the server blocking the process

Variations

Use `ThreadingHTTPServer` to handle concurrent probe requests
Return a custom JSON payload with uptime or version info

Real-world use cases

Testing Kubernetes readiness and liveness probe configuration during local development.
Simulating a degraded service endpoint in integration tests to verify health-check retry logic.
Providing a mocked /healthz route for a sidecar container in CI pipelines.

How to Create a Liveness Probe HTTP Mock in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

More from Production deployment patterns

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