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Add TraceContextPropagator (#49)
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‎trace/opencensus/trace/propagation/trace_context_http_header_format.py‎

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# Copyright 2017, OpenCensus Authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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import re
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from opencensus.trace.span_context import SpanContext
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from opencensus.trace.trace_options import TraceOptions
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_TRACE_CONTEXT_HEADER_FORMAT = \
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'([0-9a-f]{2})(-([0-9a-f]{32}))(-([0-9a-f]{16}))?(-([0-9a-f]{2}))?'
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_TRACE_CONTEXT_HEADER_RE = re.compile(_TRACE_CONTEXT_HEADER_FORMAT)
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class TraceContextPropagator(object):
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def from_header(self, header):
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"""Generate a SpanContext object using the trace context header.
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:type header: str
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:param header: Trace context header which was extracted from the HTTP
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request headers.
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:rtype: :class:`~opencensus.trace.span_context.SpanContext`
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:returns: SpanContext generated from the trace context header.
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"""
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if header is None:
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return SpanContext()
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try:
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match = re.search(_TRACE_CONTEXT_HEADER_RE, header)
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except TypeError:
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logging.warning(
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'Header should be str, got {}. Cannot parse the header.'
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.format(header.__class__.__name__))
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raise
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if match:
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version = match.group(1)
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if version == '00':
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trace_id = match.group(3)
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span_id = match.group(5)
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trace_options = match.group(7)
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if trace_options is None:
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trace_options = 1
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# Need to convert span_id from hex string to int
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span_context = SpanContext(
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trace_id=trace_id,
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span_id=int(span_id, 16),
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trace_options=TraceOptions(trace_options),
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from_header=True)
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return span_context
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else:
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logging.warning(
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'Header format version {} is not supported, generate a new'
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'context instead.'.format(version))
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else:
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logging.warning(
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'Cannot parse the header {}, generate a new context instead.'
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.format(header))
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return SpanContext()
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def to_header(self, span_context):
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"""Convert a SpanContext object to header string, using version 0.
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:type span_context:
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:class:`~opencensus.trace.span_context.SpanContext`
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:param span_context: SpanContext object.
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:rtype: str
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:returns: A trace context header string in trace context HTTP format.
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"""
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trace_id = span_context.trace_id
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span_id = span_context.span_id
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trace_options = span_context.trace_options.enabled
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# Need to convert span_id from int to hex string
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span_id_hex = hex(span_id)
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span_id = span_id_hex[2:].zfill(16)
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# Convert the trace options
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trace_options = '01' if trace_options else '00'
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header = '00-{}-{}-{}'.format(
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trace_id,
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span_id,
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trace_options)
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return header

‎trace/tests/unit/propagation/test_trace_context_http_header_format.py‎

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# Copyright 2017, OpenCensus Authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import unittest
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from opencensus.trace.propagation import trace_context_http_header_format
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class TestTraceContextPropagator(unittest.TestCase):
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def test_from_header_no_header(self):
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from opencensus.trace.span_context import SpanContext
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propagator = trace_context_http_header_format.\
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TraceContextPropagator()
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span_context = propagator.from_header(None)
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assert isinstance(span_context, SpanContext)
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def test_header_type_error(self):
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header = 1234
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propagator = trace_context_http_header_format.\
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TraceContextPropagator()
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with self.assertRaises(TypeError):
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propagator.from_header(header)
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def test_header_version_not_support(self):
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from opencensus.trace.span_context import SpanContext
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header = '01-6e0c63257de34c92bf9efcd03927272e-00f067aa0ba902b7-00'
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propagator = trace_context_http_header_format. \
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TraceContextPropagator()
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span_context = propagator.from_header(header)
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assert isinstance(span_context, SpanContext)
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def test_header_match(self):
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# Trace option is not enabled.
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header = '00-6e0c63257de34c92bf9efcd03927272e-00f067aa0ba902b7-00'
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expected_trace_id = '6e0c63257de34c92bf9efcd03927272e'
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expected_span_id = 67667974448284343
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propagator = trace_context_http_header_format.\
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TraceContextPropagator()
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span_context = propagator.from_header(header)
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self.assertEqual(span_context.trace_id, expected_trace_id)
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self.assertEqual(span_context.span_id, expected_span_id)
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self.assertFalse(span_context.trace_options.enabled)
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# Trace option is enabled.
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header = '00-6e0c63257de34c92bf9efcd03927272e-00f067aa0ba902b7-01'
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expected_trace_id = '6e0c63257de34c92bf9efcd03927272e'
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expected_span_id = 67667974448284343
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propagator = trace_context_http_header_format.\
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TraceContextPropagator()
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span_context = propagator.from_header(header)
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self.assertEqual(span_context.trace_id, expected_trace_id)
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self.assertEqual(span_context.span_id, expected_span_id)
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self.assertTrue(span_context.trace_options.enabled)
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def test_header_match_no_option(self):
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header = '00-6e0c63257de34c92bf9efcd03927272e-00f067aa0ba902b7'
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expected_trace_id = '6e0c63257de34c92bf9efcd03927272e'
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expected_span_id = 67667974448284343
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propagator = trace_context_http_header_format.\
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TraceContextPropagator()
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span_context = propagator.from_header(header)
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self.assertEqual(span_context.trace_id, expected_trace_id)
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self.assertEqual(span_context.span_id, expected_span_id)
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self.assertTrue(span_context.trace_options.enabled)
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def test_header_not_match(self):
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header = '00-invalid_trace_id-66666-00'
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trace_id = 'invalid_trace_id'
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propagator = trace_context_http_header_format.\
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TraceContextPropagator()
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span_context = propagator.from_header(header)
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self.assertNotEqual(span_context.trace_id, trace_id)
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def test_to_header(self):
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from opencensus.trace import span_context
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from opencensus.trace import trace_options
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trace_id = '6e0c63257de34c92bf9efcd03927272e'
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span_id = 67667974448284343
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span_id_hex = '00f067aa0ba902b7'
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span_context = span_context.SpanContext(
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trace_id=trace_id,
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span_id=span_id,
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trace_options=trace_options.TraceOptions('1'))
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propagator = trace_context_http_header_format.\
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TraceContextPropagator()
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header = propagator.to_header(span_context)
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expected_header = '00-{}-{}-01'.format(
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trace_id,
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span_id_hex)
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self.assertEqual(header, expected_header)

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