Allow using custom SSL context for registration requests

Pyctuator should support using custom `ssl.SSLContext` when registering
with HTTPS enabled Spring Boot Admin.

This is in addition to the option to disable certificate validation, that
should never be used except for testing, using the `PYCTUATOR_REGISTRATION_NO_CERT`
environment-variable.

Solves #65

README.md

@@ -173,7 +173,8 @@ Log in to the Spring Boot Admin UI at `http://localhost:8080` to interact with t
 When registering a service in Spring Boot Admin, note that:
 * **Docker** - If the Spring Boot Admin is running in a container while the managed service is running in the docker-host directly, the `app_url` and `pyctuator_endpoint_url` should use `host.docker.internal` as the url's host so Spring Boot Admin will be able to connect to the monitored service.
 * **Http Traces** - In order for the "Http Traces" tab to be able to hide requests sent by Spring Boot Admin to the Pyctuator endpoint, `pyctuator_endpoint_url` must be using the same host and port as `app_url`.
-* **HTTPS** - If Spring Boot Admin is using HTTPS with self-signed certificate, set the `PYCTUATOR_REGISTRATION_NO_CERT` environment variable so Pyctuator will disable certificate validation when registering (and deregistering).
+* **HTTPS** - If Pyctuator is to be registered with Spring Boot Admin using HTTPS and the default SSL context is inappropriate, you can provide your own `ssl.SSLContext` using the `ssl_context` optional parameter of the `Pyctuator` constructor.
+* **Insecure HTTPS** - If Spring Boot Admin is using HTTPS with self-signed certificate, set the `PYCTUATOR_REGISTRATION_NO_CERT` environment variable so Pyctuator will disable certificate validation when registering (and deregistering).
 
 ## Advanced Configuration
 The following sections are intended for advanced users who want to configure advanced Pyctuator features.

pyctuator/impl/spring_boot_admin_registration.py

@@ -25,7 +25,8 @@ def __init__(
             start_time: datetime,
             service_url: str,
             registration_interval_sec: float,
-            application_metadata: Optional[dict] = None
+            application_metadata: Optional[dict] = None,
+            ssl_context: Optional[ssl.SSLContext] = None,
     ) -> None:
         self.registration_url = registration_url
         self.registration_auth = registration_auth
@@ -36,6 +37,7 @@ def __init__(
         self.registration_interval_sec = registration_interval_sec
         self.instance_id = None
         self.application_metadata = application_metadata if application_metadata else {}
+        self.ssl_context = ssl_context
 
         self.should_continue_registration_schedule: bool = False
         self.disable_certificate_validation_for_https_registration: bool = \
@@ -137,8 +139,8 @@ def _http_request(self, url: str, method: str, headers: Dict[str, str], body: Op
         if url_parts.scheme == "http":
             conn = http.client.HTTPConnection(url_parts.hostname, url_parts.port)
         elif url_parts.scheme == "https":
-            context = None
-            if self.disable_certificate_validation_for_https_registration:
+            context = self.ssl_context
+            if not context and self.disable_certificate_validation_for_https_registration:
                 context = ssl.SSLContext()
                 context.verify_mode = ssl.CERT_NONE
             conn = http.client.HTTPSConnection(url_parts.hostname, url_parts.port, context=context)

pyctuator/pyctuator.py

@@ -2,6 +2,7 @@
 import atexit
 import importlib.util
 import logging
+import ssl
 from datetime import datetime, timezone
 from typing import Any, Optional, Dict, Callable
 
@@ -40,6 +41,7 @@ def __init__(
             auto_deregister: bool = True,
             metadata: Optional[dict] = None,
             additional_app_info: Optional[dict] = None,
+            ssl_context: Optional[ssl.SSLContext] = None,
     ) -> None:
         """The entry point for integrating pyctuator with a web-frameworks such as FastAPI and Flask.
 
@@ -76,6 +78,7 @@ def __init__(
         with SBA showing "offline" instances
         :param metadata: optional metadata key-value pairs that are displayed in SBA main page of an instance
         :param additional_app_info: additional arbitrary information to add to the application's "Info" section
+        :param ssl_context: optional SSL context to be used when registering with SBA
         """
 
         self.auto_deregister = auto_deregister
@@ -99,6 +102,7 @@ def __init__(
         self.boot_admin_registration_handler: Optional[BootAdminRegistrationHandler] = None
 
         self.metadata = metadata
+        self.ssl_context = ssl_context
 
         root_logger = logging.getLogger()
         # If application did not initiate logging module, add default handler to root logger
@@ -130,7 +134,8 @@ def __init__(
                             start_time,
                             app_url,
                             registration_interval_sec,
-                            self.metadata
+                            self.metadata,
+                            self.ssl_context,
                         )
 
                         # Deregister from SBA on exit