Add example of a python client

Fixes smallstep/ca-component#139

autocert/examples/hello-mtls/py-gunicorn/client.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python
+import os
+import sys
+import ssl
+import signal
+import time
+import logging
+import threading
+import http.client
+from watchdog.events import FileSystemEventHandler
+from watchdog.observers import Observer
+from urllib.parse import urlparse
+
+ca_certs = '/var/run/autocert.step.sm/root.crt'
+cert_file = '/var/run/autocert.step.sm/site.crt'
+key_file = '/var/run/autocert.step.sm/site.key'
+
+# RenewHandler is an even file system event handler that reloads the certs in
+# the context when a file is modified.
+class RenewHandler(FileSystemEventHandler):
+    def __init__(self, ctx):
+        self.ctx = ctx
+        super()
+
+    def on_modified(self, event):
+        logging.info("reloading certs ...")
+        ctx.load_cert_chain(cert_file, key_file)
+
+# Monitor is a thread that watches for changes in a path and calls to the
+# RenewHandler when a file is modified.
+class Monitor(threading.Thread):
+    def __init__(self, handler, path):
+        threading.Thread.__init__(self)
+        self.handler = handler
+        self.path = path
+
+    def run(self):
+        observer = Observer()
+        observer.schedule(self.handler, self.path)
+        observer.start()
+
+# Signal handler
+def handler(signum, frame):
+    print("exiting ...")
+    sys.exit(0)
+
+if __name__ == "__main__":
+    logging.basicConfig(level=logging.INFO, format='%(asctime)s %(message)s')
+
+    # Start signal handler to exit
+    signal.signal(signal.SIGTERM, handler)
+
+    # url from the environment
+    url = urlparse(os.environ['HELLO_MTLS_URL'])
+    
+    # ssl context
+    ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1_2)
+    ctx.set_ciphers('ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256')
+    ctx.load_verify_locations(ca_certs)
+    ctx.load_cert_chain(cert_file, key_file)
+
+    # initialize the renewer with the ssl context
+    renewer = RenewHandler(ctx)
+
+    # start file monitor
+    monitor = Monitor(renewer, os.path.dirname(cert_file))
+    monitor.start()
+
+    # Do requests
+    while True:
+        try:
+            conn = http.client.HTTPSConnection(url.netloc, context=ctx)
+            conn.request("GET", url.path)
+            r = conn.getresponse()
+            data = r.read()
+            logging.info("%d - %s - %s", r.status, r.reason, data)
+        except Exception as err:
+            print('Something went wrong:', err)
+        time.sleep(5)