feat(metrics): support configurability of TLS verification, proxy sup…

…port through requests

Introducing a new configuration flag `verify_tls` for the control that
enables the user to disable TLS verification.

Implement a custom handler for pushing metrics that uses `requests` to
benefit of its feature set like proxy support.

Signed-off-by: Mattias Cockburn <[email protected]>

CHANGELOG.md

@@ -4,6 +4,17 @@
 
 [Unreleased]: https://github.com/chaostoolkit/chaostoolkit-prometheus/compare/0.6.0...HEAD
 
+### Added
+
+- Add new `verify_tls` flag for the control to disable/enable the verification of TLS certificates
+
+### Changed
+
+- Implemented a custom handler for the prometheus `push_to_gateway` function that uses `requests`.
+  This enables features like the use of HTTP proxies.
+- Allow setting of `experiment_ref`, `trace_id`, `pushgateway_url` and `verify_tls` through a
+  `configuration` block. Direct configuration through arguments is still possible.
+
 ## [0.6.0][] - 2023-09-19
 
 [0.6.0]: https://github.com/chaostoolkit/chaostoolkit-prometheus/compare/0.5.0...0.6.0

chaosprometheus/metrics.py

@@ -1,8 +1,8 @@
 from secrets import token_hex
-from typing import Dict, List
+from typing import Any, Callable, Dict, List
 
 from chaoslib import __version__, experiment_hash
-from chaoslib.types import Experiment, Journal
+from chaoslib.types import Configuration, Experiment, Journal
 from prometheus_client import (
     CollectorRegistry,
     Counter,
@@ -11,6 +11,7 @@
     Histogram,
     push_to_gateway,
 )
+from requests import Session
 
 __all__ = ["configure_control", "after_experiment_control"]
 
@@ -19,12 +20,14 @@
 
 
 def configure_control(
-    experiment: Experiment,
+    configuration: Configuration = None,
+    experiment: Experiment = None,
     pushgateway_url: str = "http://localhost:9091",
     job: str = "chaostoolkit",
     grouping_key: Dict[str, str] = None,
     trace_id: str = None,
     experiment_ref: str = None,
+    verify_tls: bool = None,
     **kwargs
 ):
     """
@@ -47,8 +50,22 @@ def configure_control(
     provided, it'll be set to a random string as a label.
     """
     global collector
+
+    pushgateway_url = pushgateway_url or configuration.get(
+        "pushgateway_url", "http://localhost:9091"
+    )
+    experiment_ref = experiment_ref or configuration.get("experiment_ref")
+    trace_id = trace_id or configuration.get("trace_id")
+    verify_tls = verify_tls or configuration.get("verify_tls")
+
     collector = PrometheusCollector(
-        pushgateway_url, job, trace_id, experiment_ref, grouping_key, experiment
+        pushgateway_url,
+        job,
+        trace_id,
+        experiment_ref,
+        grouping_key,
+        experiment,
+        verify_tls,
     )
 
 
@@ -74,6 +91,8 @@ def after_experiment_control(state: Journal, *args, **kwargs) -> None:
 # Private functions
 ###############################################################################
 class PrometheusCollector:
+    verify_tls = True
+
     def __init__(
         self,
         pushgateway_url: str,
@@ -82,6 +101,7 @@ def __init__(
         experiment_ref: str,
         grouping_key: Dict[str, str],
         experiment: Experiment,
+        verify_tls: bool,
     ) -> None:
         self.pushgateway_url = pushgateway_url
         self.job = job
@@ -90,6 +110,8 @@ def __init__(
         self.grouping_key = grouping_key or {
             "chaostoolkit_experiment_ref": self.experiment_ref
         }
+        if verify_tls is not None:
+            PrometheusCollector.verify_tls = verify_tls
 
         labels = [
             "source",
@@ -161,3 +183,25 @@ def push(self) -> None:
             registry=self.registry,
             grouping_key=self.grouping_key,
         )
+
+
+def _custom_handler(
+    url: str,
+    method: str,
+    timeout: int,
+    headers: list,
+    data: Any,
+) -> Callable:
+    """
+    Bare bones custom handler for pushing metrics to enable more complex
+    scenarios. This function is fed into push_to_gateway()
+    We also use requests to benefit from its feature set like e.g. proxy support
+    """
+
+    def handler() -> None:
+        s = Session()
+        s.verify = PrometheusCollector.verify_tls
+        h = {k: v for k, v in headers}
+        s.request(url=url, method=method, headers=h, data=data, timeout=timeout)
+
+    return handler