Vendor the aiohttp instrumentation code and add it to the aiohttp mid…

…dleware list

Closes #3829

CHANGES/3829.doc

@@ -0,0 +1 @@
+Adds the Telemetry section to the docs with information about OpenTelemetry and its usage on Pulp.

CHANGES/3829.feature

@@ -0,0 +1 @@
+Implemented OpenTelemetry support and enabled tracing and metrics for the pulp-content app.

docs/components.rst

@@ -142,3 +142,19 @@ An example payload:
     	}],
         "postgresqlVersion": 90200
     }
+
+
+.. _telemetry:
+
+Telemetry Support
+-----------------
+
+New Pulp installations can obtain telemetry data, like the number of requests, active connections and latency response for both `pulp-api` and `pulp-content` using OpenTelemetry. You can read more about `OpenTelemetry here <https://opentelemetry.io>`_.
+
+To enable it you will need to set the following environment variables:
+
+* ``PULP_OTEL_ENABLED`` set to ``True``.
+* ``OTEL_EXPORTER_OTLP_ENDPOINT`` set to the address of your OpenTelemetry Collector instance ex. ``http://otel-collector:4318``.
+* ``OTEL_EXPORTER_OTLP_PROTOCOL`` set to ``http/protobuf``.
+
+You will need to run an instance of OpenTelemetry Collector. You can read more about the `OpenTelemetry Collector here <https://opentelemetry.io/docs/collector/>`_.

pulpcore/content/__init__.py

@@ -25,11 +25,14 @@
 
 from .handler import Handler  # noqa: E402: module level not at top of file
 from .authentication import authenticate  # noqa: E402: module level not at top of file
+from .instrumentation import (  # noqa: E402: module level not at top of file
+    middleware as instrumentation,
+)
 
 
 log = logging.getLogger(__name__)
 
-app = web.Application(middlewares=[authenticate])
+app = web.Application(middlewares=[authenticate, instrumentation])
 
 CONTENT_MODULE_NAME = "content"
 

pulpcore/content/instrumentation.py

@@ -0,0 +1,247 @@
+# This code is based on the original PR which could be found
+# here. https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1800
+# The idea is to remove this module when the PR or other alternative
+# gets merged into opentelemetry-python-contrib
+
+import urllib
+from aiohttp import web
+from multidict import CIMultiDictProxy
+from timeit import default_timer
+
+from opentelemetry import context, trace, metrics
+from opentelemetry.instrumentation.instrumentor import BaseInstrumentor
+from opentelemetry.instrumentation.utils import http_status_to_status_code
+from opentelemetry.propagators.textmap import Getter
+from opentelemetry.semconv.trace import SpanAttributes
+from opentelemetry.semconv.metrics import MetricInstruments
+from opentelemetry.trace.status import Status, StatusCode
+from opentelemetry.util.http import get_excluded_urls
+from opentelemetry.util.http import remove_url_credentials
+
+from typing import Tuple
+
+
+_SUPPRESS_HTTP_INSTRUMENTATION_KEY = "suppress_http_instrumentation"
+
+_duration_attrs = [
+    SpanAttributes.HTTP_METHOD,
+    SpanAttributes.HTTP_HOST,
+    SpanAttributes.HTTP_SCHEME,
+    SpanAttributes.HTTP_STATUS_CODE,
+    SpanAttributes.HTTP_FLAVOR,
+    SpanAttributes.HTTP_SERVER_NAME,
+    SpanAttributes.NET_HOST_NAME,
+    SpanAttributes.NET_HOST_PORT,
+    SpanAttributes.HTTP_ROUTE,
+]
+
+_active_requests_count_attrs = [
+    SpanAttributes.HTTP_METHOD,
+    SpanAttributes.HTTP_HOST,
+    SpanAttributes.HTTP_SCHEME,
+    SpanAttributes.HTTP_FLAVOR,
+    SpanAttributes.HTTP_SERVER_NAME,
+]
+
+tracer = trace.get_tracer(__name__)
+meter = metrics.get_meter(__name__)
+_excluded_urls = get_excluded_urls("AIOHTTP_SERVER")
+
+
+def _parse_duration_attrs(req_attrs):
+    duration_attrs = {}
+    for attr_key in _duration_attrs:
+        if req_attrs.get(attr_key) is not None:
+            duration_attrs[attr_key] = req_attrs[attr_key]
+    return duration_attrs
+
+
+def _parse_active_request_count_attrs(req_attrs):
+    active_requests_count_attrs = {}
+    for attr_key in _active_requests_count_attrs:
+        if req_attrs.get(attr_key) is not None:
+            active_requests_count_attrs[attr_key] = req_attrs[attr_key]
+    return active_requests_count_attrs
+
+
+def get_default_span_details(request: web.Request) -> Tuple[str, dict]:
+    """Default implementation for get_default_span_details
+    Args:
+        scope: the asgi scope dictionary
+    Returns:
+        a tuple of the span name, and any attributes to attach to the span.
+    """
+    span_name = request.path.strip() or f"HTTP {request.method}"
+    return span_name, {}
+
+
+def _get_view_func(request) -> str:
+    """TODO: is this useful??"""
+    try:
+        return request.match_info.handler.__name__
+    except AttributeError:
+        return "unknown"
+
+
+def collect_request_attributes(request: web.Request):
+    """Collects HTTP request attributes from the ASGI scope and returns a
+    dictionary to be used as span creation attributes."""
+
+    server_host, port, http_url = (
+        request.url.host,
+        request.url.port,
+        str(request.url),
+    )
+    query_string = request.query_string
+    if query_string and http_url:
+        if isinstance(query_string, bytes):
+            query_string = query_string.decode("utf8")
+        http_url += "?" + urllib.parse.unquote(query_string)
+
+    result = {
+        SpanAttributes.HTTP_SCHEME: request.scheme,
+        SpanAttributes.HTTP_HOST: server_host,
+        SpanAttributes.NET_HOST_PORT: port,
+        SpanAttributes.HTTP_ROUTE: _get_view_func(request),
+        SpanAttributes.HTTP_FLAVOR: f"{request.version.major}.{request.version.minor}",
+        SpanAttributes.HTTP_TARGET: request.path,
+        SpanAttributes.HTTP_URL: remove_url_credentials(http_url),
+    }
+
+    http_method = request.method
+    if http_method:
+        result[SpanAttributes.HTTP_METHOD] = http_method
+
+    http_host_value_list = [request.host] if type(request.host) != list else request.host
+    if http_host_value_list:
+        result[SpanAttributes.HTTP_SERVER_NAME] = ",".join(http_host_value_list)
+    http_user_agent = request.headers.get("user-agent")
+    if http_user_agent:
+        result[SpanAttributes.HTTP_USER_AGENT] = http_user_agent
+
+    # remove None values
+    result = {k: v for k, v in result.items() if v is not None}
+
+    return result
+
+
+def set_status_code(span, status_code):
+    """Adds HTTP response attributes to span using the status_code argument."""
+    if not span.is_recording():
+        return
+    try:
+        status_code = int(status_code)
+    except ValueError:
+        span.set_status(
+            Status(
+                StatusCode.ERROR,
+                "Non-integer HTTP status: " + repr(status_code),
+            )
+        )
+    else:
+        span.set_attribute(SpanAttributes.HTTP_STATUS_CODE, status_code)
+        span.set_status(Status(http_status_to_status_code(status_code, server_span=True)))
+
+
+class AiohttpGetter(Getter):
+    """Extract current trace from headers"""
+
+    def get(self, carrier, key: str):
+        """Getter implementation to retrieve a HTTP header value from the ASGI
+        scope.
+
+        Args:
+            carrier: ASGI scope object
+            key: header name in scope
+        Returns:
+            A list with a single string with the header value if it exists,
+                else None.
+        """
+        headers: CIMultiDictProxy = carrier.headers
+        if not headers:
+            return None
+        return headers.getall(key, None)
+
+    def keys(self, carrier: dict):
+        return list(carrier.keys())
+
+
+getter = AiohttpGetter()
+
+
+@web.middleware
+async def middleware(request, handler):
+    """Middleware for aiohttp implementing tracing logic"""
+    if (
+        context.get_value("suppress_instrumentation")
+        or context.get_value(_SUPPRESS_HTTP_INSTRUMENTATION_KEY)
+        or _excluded_urls.url_disabled(request.url.path)
+    ):
+        return await handler(request)
+
+    span_name, additional_attributes = get_default_span_details(request)
+
+    req_attrs = collect_request_attributes(request)
+    duration_attrs = _parse_duration_attrs(req_attrs)
+    active_requests_count_attrs = _parse_active_request_count_attrs(req_attrs)
+
+    duration_histogram = meter.create_histogram(
+        name=MetricInstruments.HTTP_SERVER_DURATION,
+        unit="ms",
+        description="measures the duration of the inbound HTTP request",
+    )
+
+    active_requests_counter = meter.create_up_down_counter(
+        name=MetricInstruments.HTTP_SERVER_ACTIVE_REQUESTS,
+        unit="requests",
+        description="measures the number of concurrent HTTP requests those are currently in flight",
+    )
+
+    with tracer.start_as_current_span(
+        span_name,
+        kind=trace.SpanKind.SERVER,
+    ) as span:
+        attributes = collect_request_attributes(request)
+        attributes.update(additional_attributes)
+        span.set_attributes(attributes)
+        start = default_timer()
+        active_requests_counter.add(1, active_requests_count_attrs)
+        try:
+            resp = await handler(request)
+            set_status_code(span, resp.status)
+        except web.HTTPException as ex:
+            set_status_code(span, ex.status_code)
+            raise
+        finally:
+            duration = max(round((default_timer() - start) * 1000), 0)
+            duration_histogram.record(duration, duration_attrs)
+            active_requests_counter.add(-1, active_requests_count_attrs)
+        return resp
+
+
+class _InstrumentedApplication(web.Application):
+    """Insert tracing middleware"""
+
+    def __init__(self, *args, **kwargs):
+        middlewares = kwargs.pop("middlewares", [])
+        middlewares.insert(0, middleware)
+        kwargs["middlewares"] = middlewares
+        super().__init__(*args, **kwargs)
+
+
+class AioHttpServerInstrumentor(BaseInstrumentor):
+    # pylint: disable=protected-access,attribute-defined-outside-init
+    """An instrumentor for aiohttp.web.Application
+
+    See `BaseInstrumentor`
+    """
+
+    def _instrument(self, **kwargs):
+        self._original_app = web.Application
+        setattr(web, "Application", _InstrumentedApplication)
+
+    def _uninstrument(self, **kwargs):
+        setattr(web, "Application", self._original_app)
+
+    def instrumentation_dependencies(self):
+        return self._instruments