Add tls_auth_handler for push gateway

Support pushing metrics to a push gateway instance running with TLS
Authentication. A user will need to provide the appropriate certificates
to send to the server, and can specify additional parameters depending
on their setup.

Signed-off-by: Chris Marchbanks <[email protected]>

README.md

@@ -471,6 +471,24 @@ g.set_to_current_time()
 push_to_gateway('localhost:9091', job='batchA', registry=registry, handler=my_auth_handler)
 ```
 
+TLS Auth is also supported when using the push gateway with a special handler.
+
+```python
+from prometheus_client import CollectorRegistry, Gauge, push_to_gateway
+from prometheus_client.exposition import tls_handler
+
+
+def my_auth_handler(url, method, timeout, headers, data):
+    certfile = 'client-crt.pem'
+    keyfile = 'client-key.pem'
+    return tls_auth_handler(url, method, timeout, headers, data, certfile, keyfile)
+
+registry = CollectorRegistry()
+g = Gauge('job_last_success_unixtime', 'Last time a batch job successfully finished', registry=registry)
+g.set_to_current_time()
+push_to_gateway('localhost:9091', job='batchA', registry=registry, handler=my_auth_handler)
+```
+
 ## Bridges
 
 It is also possible to expose metrics to systems other than Prometheus.

prometheus_client/exposition.py

@@ -5,13 +5,15 @@
 import os
 import socket
 from socketserver import ThreadingMixIn
+import ssl
 import sys
 import threading
-from typing import Any, Callable, Dict, List, Optional, Sequence, Tuple
+from typing import Any, Callable, Dict, List, Optional, Sequence, Tuple, Union
 from urllib.error import HTTPError
 from urllib.parse import parse_qs, quote_plus, urlparse
 from urllib.request import (
-    build_opener, HTTPHandler, HTTPRedirectHandler, Request,
+    BaseHandler, build_opener, HTTPHandler, HTTPRedirectHandler, HTTPSHandler,
+    Request,
 )
 import warnings
 from wsgiref.simple_server import make_server, WSGIRequestHandler, WSGIServer
@@ -324,7 +326,7 @@ def _make_handler(
         timeout: Optional[float],
         headers: Sequence[Tuple[str, str]],
         data: bytes,
-        base_handler: type,
+        base_handler: Union[BaseHandler, type],
 ) -> Callable[[], None]:
     def handle() -> None:
         request = Request(url, data=data)
@@ -399,6 +401,40 @@ def handle():
     return handle
 
 
+def tls_auth_handler(
+        url: str,
+        method: str,
+        timeout: Optional[float],
+        headers: List[Tuple[str, str]],
+        data: bytes,
+        certfile: str,
+        keyfile: str,
+        cafile: Optional[str] = None,
+        protocol: int = ssl.PROTOCOL_TLS_CLIENT,
+        insecure_skip_verify: bool = False,
+) -> Callable[[], None]:
+    """Handler that implements an HTTPS connection with TLS Auth.
+
+    The default protocol (ssl.PROTOCOL_TLS_CLIENT) will also enable
+    ssl.CERT_REQUIRED and SSLContext.check_hostname by default. This can be
+    disabled by setting insecure_skip_verify to True.
+    
+    Both this handler and the TLS feature on pushgateay are experimental."""
+    context = ssl.SSLContext(protocol=protocol)
+    if cafile is not None:
+        context.load_verify_locations(cafile)
+    else:
+        context.load_default_certs()
+
+    if insecure_skip_verify:
+        context.check_hostname = False
+        context.verify_mode = ssl.CERT_NONE
+
+    context.load_cert_chain(certfile=certfile, keyfile=keyfile)
+    handler = HTTPSHandler(context=context)
+    return _make_handler(url, method, timeout, headers, data, handler)
+
+
 def push_to_gateway(
         gateway: str,
         job: str,

tests/certs/cert.pem

@@ -0,0 +1,32 @@
+-----BEGIN CERTIFICATE-----
+MIIFkzCCA3ugAwIBAgIUWhYKmrh+gF5pZ7Yqj41cWJ2pRzkwDQYJKoZIhvcNAQEL
+BQAwWTELMAkGA1UEBhMCVVMxEzARBgNVBAgMClNvbWUtU3RhdGUxITAfBgNVBAoM
+GEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDESMBAGA1UEAwwJbG9jYWxob3N0MB4X
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+7GbIme6H2ZbNCZngf6eCbdsoHAGkQZpD3wYFHLmTFDCNmjMJteb3YFMNHyU5eh8C
+2bTp4D+pifgFRo3Mc23kuRXiIzyrhg/eOHl+Qi2V8BpXP/7bI27FZXglp9rzhP57
+YMfBeoOejRgRHJTeMPhBbEevQyqpb9ecZxpuGV77Pi3S5IA26fe3pZQCHRceufZr
+YKWLOCt2jZJ0y9KM4wdVg40yr6BVZqy2OPqDn64q0pAgMHG24XrxxuaFISjgPOgx
+bYhhTUG/4Dkb1BWhfEv4EwEf/uDxhHE8k6LoKk3Qb+aOzPr2PKGvW3yBHEFNSmKH
+x3SB8xxj/IOiA+em+TLtKd66gG0T0b8cPt037k+D3a0BqC9d2sVs
+-----END CERTIFICATE-----

tests/certs/key.pem

@@ -0,0 +1,52 @@
+-----BEGIN PRIVATE KEY-----
+MIIJQQIBADANBgkqhkiG9w0BAQEFAASCCSswggknAgEAAoICAQDGzq/1z9s20DRO
+M07NKgirYJC4GGNa3yfBUbtSOfckFK8Lbrd+hGo4bSgaFoWtu3getuKRh5Kjm7/Q
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+YdxZTB2pN96tqnBm8vyvi81Cdy/x
+-----END PRIVATE KEY-----

tests/test_exposition.py

@@ -1,4 +1,5 @@
 from http.server import BaseHTTPRequestHandler, HTTPServer
+import os
 import threading
 import time
 import unittest
@@ -14,7 +15,7 @@
 from prometheus_client.core import GaugeHistogramMetricFamily, Timestamp
 from prometheus_client.exposition import (
     basic_auth_handler, choose_encoder, choose_formatter, default_handler,
-    MetricsHandler, passthrough_redirect_handler,
+    MetricsHandler, passthrough_redirect_handler, tls_auth_handler,
 )
 import prometheus_client.openmetrics.exposition as openmetrics
 
@@ -343,6 +344,17 @@ def my_auth_handler(url, method, timeout, headers, data):
         self.assertEqual(self.requests[0][0].headers.get('content-type'), CONTENT_TYPE_LATEST)
         self.assertEqual(self.requests[0][1], b'# HELP g help\n# TYPE g gauge\ng 0.0\n')
 
+    def test_push_with_tls_auth_handler(self):
+        def my_auth_handler(url, method, timeout, headers, data):
+            certs_dir = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'certs')
+            return tls_auth_handler(url, method, timeout, headers, data, os.path.join(certs_dir, "cert.pem"), os.path.join(certs_dir, "key.pem"))
+
+        push_to_gateway(self.address, "my_job_with_tls_auth", self.registry, handler=my_auth_handler)
+        self.assertEqual(self.requests[0][0].command, 'PUT')
+        self.assertEqual(self.requests[0][0].path, '/metrics/job/my_job_with_tls_auth')
+        self.assertEqual(self.requests[0][0].headers.get('content-type'), CONTENT_TYPE_LATEST)
+        self.assertEqual(self.requests[0][1], b'# HELP g help\n# TYPE g gauge\ng 0.0\n')
+
     def test_push_with_redirect_handler(self):
         def my_redirect_handler(url, method, timeout, headers, data):
             return passthrough_redirect_handler(url, method, timeout, headers, data)