propagators: add trace-context validation service

.circleci/config.yml

@@ -110,6 +110,17 @@ jobs:
       - *persist_to_workspace_step
       - *save_cache_step
 
+  trace-context:
+    docker:
+      - *test_runner
+    resource_class: *resource_class
+    steps:
+      - checkout
+      - *restore_cache_step
+      - run: scripts/run-tox-scenario '^py..-trace-context'
+      - *persist_to_workspace_step
+      - *save_cache_step
+
   boto:
     docker:
       - *test_runner
@@ -901,6 +912,9 @@ workflows:
       - tracer:
           requires:
             - flake8
+      - trace-context:
+          requires:
+            - flake8
       - unit_tests:
           requires:
             - flake8
@@ -960,6 +974,7 @@ workflows:
             - test_logging
             - tornado
             - tracer
+            - trace-context
             - unit_tests
             - vertica
       - deploy_dev:

oteltrace/propagation/w3c.py

@@ -4,9 +4,29 @@
 from ..ext import priority
 
 
+_KEY_WITHOUT_VENDOR_FORMAT = r'[a-z][_0-9a-z\-\*\/]{0,255}'
+_KEY_WITH_VENDOR_FORMAT = (
+    r'[a-z][_0-9a-z\-\*\/]{0,240}@[a-z][_0-9a-z\-\*\/]{0,13}'
+)
+
+_KEY_FORMAT = _KEY_WITHOUT_VENDOR_FORMAT + '|' + _KEY_WITH_VENDOR_FORMAT
+_VALUE_FORMAT = (
+    r'[\x20-\x2b\x2d-\x3c\x3e-\x7e]{0,255}[\x21-\x2b\x2d-\x3c\x3e-\x7e]'
+)
+
+_DELIMITER_FORMAT = '[ \t]*,[ \t]*'
+_MEMBER_FORMAT = '({})(=)({})[ \t]*'.format(_KEY_FORMAT, _VALUE_FORMAT)
+
+_DELIMITER_FORMAT_RE = re.compile(_DELIMITER_FORMAT)
+_MEMBER_FORMAT_RE = re.compile(_MEMBER_FORMAT)
+
+_TRACECONTEXT_MAXIMUM_TRACESTATE_KEYS = 32
+
+
 class W3CHTTPPropagator:
     """w3c compatible propagator"""
     _TRACEPARENT_HEADER_NAME = 'traceparent'
+    _TRACESTATE_HEADER_NAME = 'tracestate'
     _TRACEPARENT_HEADER_FORMAT = (
         '^[ \t]*([0-9a-f]{2})-([0-9a-f]{32})-([0-9a-f]{16})-([0-9a-f]{2})(-.*)?[ \t]*$'
     )
@@ -29,6 +49,10 @@ def inject(self, span_context, headers):
         )
 
         headers[self._TRACEPARENT_HEADER_NAME] = traceparent_string
+        # is there is state in the context propagate it
+        if hasattr(span_context, 'tracestate'):
+            tracestate_string = _format_tracestate(span_context.tracestate)
+            headers[self._TRACESTATE_HEADER_NAME] = tracestate_string
 
     def extract(self, headers):
         if not headers:
@@ -57,7 +81,6 @@ def extract(self, headers):
         trace_id = int(trace_id_str, 16)
         span_id = int(span_id_str, 16)
         trace_options = int(trace_options_str, 16)
-        # TODO: probably not needed
         if trace_id == 0 or span_id == 0:
             return Context()
 
@@ -68,8 +91,69 @@ def extract(self, headers):
         else:
             sampling_priority = priority.AUTO_REJECT
 
-        return Context(
+        tracestate_header = headers.get(self._TRACESTATE_HEADER_NAME)
+        tracestate = _parse_tracestate(tracestate_header)
+
+        ctx = Context(
             trace_id=trace_id,
             span_id=span_id,
             sampling_priority=sampling_priority,
         )
+
+        ctx.tracestate = tracestate
+
+        return ctx
+
+
+def _parse_tracestate(header):
+    """Parse one or more w3c tracestate header into a TraceState.
+
+    Args:
+        string: the value of the tracestate header.
+
+    Returns:
+        A valid TraceState that contains values extracted from
+        the tracestate header.
+
+        If the format of one headers is illegal, all values will
+        be discarded and an empty tracestate will be returned.
+
+        If the number of keys is beyond the maximum, all values
+        will be discarded and an empty tracestate will be returned.
+    """
+    tracestate = {}
+    value_count = 0
+
+    if header is None:
+        return {}
+    for member in re.split(_DELIMITER_FORMAT_RE, header):
+        # empty members are valid, but no need to process further.
+        if not member:
+            continue
+        match = _MEMBER_FORMAT_RE.fullmatch(member)
+        if not match:
+            # TODO: log this?
+            return {}
+        key, _eq, value = match.groups()
+        if key in tracestate:  # pylint:disable=E1135
+            # duplicate keys are not legal in
+            # the header, so we will remove
+            return {}
+        tracestate[key] = value
+        value_count += 1
+        if value_count > _TRACECONTEXT_MAXIMUM_TRACESTATE_KEYS:
+            return {}
+    return tracestate
+
+
+def _format_tracestate(tracestate):
+    """Parse a w3c tracestate header into a TraceState.
+
+    Args:
+        tracestate: the tracestate header to write
+
+    Returns:
+        A string that adheres to the w3c tracestate
+        header format.
+    """
+    return ','.join(key + '=' + value for key, value in tracestate.items())

tests/propagation/test_w3c.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+set -e
+pwd
+# hard-coding the git tag to ensure stable builds.
+TRACECONTEXT_GIT_TAG="98f210efd89c63593dce90e2bae0a1bdcb986f51"
+# clone w3c tracecontext tests
+mkdir -p target
+rm -rf ./target/trace-context
+git clone https://github.com/w3c/trace-context ./target/trace-context
+cd ./target/trace-context && git checkout $TRACECONTEXT_GIT_TAG && cd -
+# start example service, which propagates trace-context by default.
+python tests/propagation/w3c_server_test.py 1>&2 &
+EXAMPLE_SERVER_PID=$!
+# give the app server a little time to start up. Not adding some sort
+# of delay would cause many of the tracecontext tests to fail being
+# unable to connect.
+sleep 1
+onshutdown()
+{
+    # send a sigint, to ensure
+    # it is caught as a KeyboardInterrupt in the
+    # example service.
+    kill $EXAMPLE_SERVER_PID
+}
+trap onshutdown EXIT
+cd ./target/trace-context/test
+python test.py http://127.0.0.1:5000/verify-tracecontext

tests/propagation/w3c_server_test.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+#
+# Copyright 2019, OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+This server is intended to be used with the W3C tracecontext validation
+Service. It implements the APIs needed to be exercised by the test bed.
+"""
+
+from oteltrace import patch_all
+patch_all()
+
+import json  # noqa: E402
+import flask  # noqa: E402
+import requests  # noqa: E402
+
+from oteltrace.propagation.w3c import W3CHTTPPropagator  # noqa: E402
+from oteltrace import tracer  # noqa: E402
+
+tracer.configure(
+    http_propagator=W3CHTTPPropagator,
+)
+
+app = flask.Flask(__name__)
+
+
+@app.route('/verify-tracecontext', methods=['POST'])
+def verify_tracecontext():
+    """Upon reception of some payload, sends a request back to the designated
+    url.
+
+    This route is designed to be testable with the w3c tracecontext server /
+    client test.
+    """
+    for action in flask.request.json:
+        requests.post(
+            url=action['url'],
+            data=json.dumps(action['arguments']),
+            headers={
+                'Accept': 'application/json',
+                'Content-Type': 'application/json; charset=utf-8',
+            },
+            timeout=5.0,
+        )
+    return 'hello'
+
+
+if __name__ == '__main__':
+    app.run(debug=True)

tox.ini

@@ -24,6 +24,7 @@ envlist =
     {py34,py35,py36,py37}-oteltracerun
     {py34,py35,py36,py37}-test_utils
     {py34,py35,py36,py37}-test_logging
+    py37-trace-context
 # Integrations environments
     aiobotocore_contrib-py34-aiobotocore{02,03,04}
     aiobotocore_contrib-{py35,py36}-aiobotocore{02,03,04,05,07,08,09,010}
@@ -331,6 +332,9 @@ deps =
     tornado50: tornado>=5.0,<5.1
     tornado51: tornado>=5.1,<5.2
     tornado60: tornado>=6.0,<6.1
+    trace-context: aiohttp
+    trace-context: flask
+    trace-context: requests
     vertica060: vertica-python>=0.6.0,<0.7.0
     vertica070: vertica-python>=0.7.0,<0.8.0
     webtest: WebTest
@@ -341,6 +345,7 @@ passenv=TEST_*
 commands =
 # run only essential tests related to the tracing client
     tracer: pytest {posargs} --ignore="tests/contrib" --ignore="tests/commands" --ignore="tests/unit" --ignore="tests/internal" tests
+    trace-context: {toxinidir}/tests/propagation/test_w3c.sh
 # run only the `oteltrace.internal` tests
     internal: pytest {posargs} tests/internal
 # Contribs