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Opentracing Utils (#5722) 

* Add decerators for tracing functions

* Use the new clean contexts

* Context and edu utils

* Move opentracing setters

* Move whitelisting

* Sectioning comments

* Better args wrapper

* Docstrings

Co-Authored-By: Erik Johnston <erik@matrix.org>

* Remove unused methods.

* Don't use global

* One tracing decorator to rule them all.
This commit is contained in:
Jorik Schellekens 2019-07-23 13:31:16 +01:00 committed by GitHub
parent 841b12867e
commit 18a466b84e
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3 changed files with 357 additions and 101 deletions
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1
changelog.d/5722.misc Normal file
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@ -0,0 +1 @@
Add a set of opentracing utils.

455
synapse/logging/opentracing.py
View File

@ -11,7 +11,7 @@
# 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.import opentracing
# limitations under the License.
# NOTE
@ -150,10 +150,13 @@ Gotchas
"""
import contextlib
import inspect
import logging
import re
from functools import wraps
from canonicaljson import json
from twisted.internet import defer
from synapse.config import ConfigError
@ -173,36 +176,12 @@ except ImportError:
logger = logging.getLogger(__name__)
class _DumTagNames(object):
"""wrapper of opentracings tags. We need to have them if we
want to reference them without opentracing around. Clearly they
should never actually show up in a trace. `set_tags` overwrites
these with the correct ones."""
# Block everything by default
# A regex which matches the server_names to expose traces for.
# None means 'block everything'.
_homeserver_whitelist = None
INVALID_TAG = "invalid-tag"
COMPONENT = INVALID_TAG
DATABASE_INSTANCE = INVALID_TAG
DATABASE_STATEMENT = INVALID_TAG
DATABASE_TYPE = INVALID_TAG
DATABASE_USER = INVALID_TAG
ERROR = INVALID_TAG
HTTP_METHOD = INVALID_TAG
HTTP_STATUS_CODE = INVALID_TAG
HTTP_URL = INVALID_TAG
MESSAGE_BUS_DESTINATION = INVALID_TAG
PEER_ADDRESS = INVALID_TAG
PEER_HOSTNAME = INVALID_TAG
PEER_HOST_IPV4 = INVALID_TAG
PEER_HOST_IPV6 = INVALID_TAG
PEER_PORT = INVALID_TAG
PEER_SERVICE = INVALID_TAG
SAMPLING_PRIORITY = INVALID_TAG
SERVICE = INVALID_TAG
SPAN_KIND = INVALID_TAG
SPAN_KIND_CONSUMER = INVALID_TAG
SPAN_KIND_PRODUCER = INVALID_TAG
SPAN_KIND_RPC_CLIENT = INVALID_TAG
SPAN_KIND_RPC_SERVER = INVALID_TAG
# Util methods
def only_if_tracing(func):
@ -219,11 +198,13 @@ def only_if_tracing(func):
return _only_if_tracing_inner
# A regex which matches the server_names to expose traces for.
# None means 'block everything'.
_homeserver_whitelist = None
@contextlib.contextmanager
def _noop_context_manager(*args, **kwargs):
"""Does exactly what it says on the tin"""
yield
tags = _DumTagNames
# Setup
def init_tracer(config):
@ -260,13 +241,39 @@ def init_tracer(config):
tags = opentracing.tags
@contextlib.contextmanager
def _noop_context_manager(*args, **kwargs):
"""Does absolutely nothing really well. Can be entered and exited arbitrarily.
Good substitute for an opentracing scope."""
yield
# Whitelisting
@only_if_tracing
def set_homeserver_whitelist(homeserver_whitelist):
"""Sets the homeserver whitelist
Args:
homeserver_whitelist (Iterable[str]): regex of whitelisted homeservers
"""
global _homeserver_whitelist
if homeserver_whitelist:
# Makes a single regex which accepts all passed in regexes in the list
_homeserver_whitelist = re.compile(
"({})".format(")|(".join(homeserver_whitelist))
)
@only_if_tracing
def whitelisted_homeserver(destination):
"""Checks if a destination matches the whitelist
Args:
destination (str)
"""
_homeserver_whitelist
if _homeserver_whitelist:
return _homeserver_whitelist.match(destination)
return False
# Start spans and scopes
# Could use kwargs but I want these to be explicit
def start_active_span(
operation_name,
@ -285,8 +292,10 @@ def start_active_span(
Returns:
scope (Scope) or noop_context_manager
"""
if opentracing is None:
return _noop_context_manager()
else:
# We need to enter the scope here for the logcontext to become active
return opentracing.tracer.start_active_span(
@ -300,63 +309,13 @@ def start_active_span(
)
@only_if_tracing
def close_active_span():
"""Closes the active span. This will close it's logcontext if the context
was made for the span"""
opentracing.tracer.scope_manager.active.__exit__(None, None, None)
@only_if_tracing
def set_tag(key, value):
"""Set's a tag on the active span"""
opentracing.tracer.active_span.set_tag(key, value)
@only_if_tracing
def log_kv(key_values, timestamp=None):
"""Log to the active span"""
opentracing.tracer.active_span.log_kv(key_values, timestamp)
# Note: we don't have a get baggage items because we're trying to hide all
# scope and span state from synapse. I think this method may also be useless
# as a result
@only_if_tracing
def set_baggage_item(key, value):
"""Attach baggage to the active span"""
opentracing.tracer.active_span.set_baggage_item(key, value)
@only_if_tracing
def set_operation_name(operation_name):
"""Sets the operation name of the active span"""
opentracing.tracer.active_span.set_operation_name(operation_name)
@only_if_tracing
def set_homeserver_whitelist(homeserver_whitelist):
"""Sets the whitelist
Args:
homeserver_whitelist (iterable of strings): regex of whitelisted homeservers
"""
global _homeserver_whitelist
if homeserver_whitelist:
# Makes a single regex which accepts all passed in regexes in the list
_homeserver_whitelist = re.compile(
"({})".format(")|(".join(homeserver_whitelist))
)
@only_if_tracing
def whitelisted_homeserver(destination):
"""Checks if a destination matches the whitelist
Args:
destination (String)"""
if _homeserver_whitelist:
return _homeserver_whitelist.match(destination)
return False
def start_active_span_follows_from(operation_name, contexts):
if opentracing is None:
return _noop_context_manager()
else:
references = [opentracing.follows_from(context) for context in contexts]
scope = start_active_span(operation_name, references=references)
return scope
def start_active_span_from_context(
@ -372,12 +331,16 @@ def start_active_span_from_context(
Extracts a span context from Twisted Headers.
args:
headers (twisted.web.http_headers.Headers)
For the other args see opentracing.tracer
returns:
span_context (opentracing.span.SpanContext)
"""
# Twisted encodes the values as lists whereas opentracing doesn't.
# So, we take the first item in the list.
# Also, twisted uses byte arrays while opentracing expects strings.
if opentracing is None:
return _noop_context_manager()
@ -395,17 +358,90 @@ def start_active_span_from_context(
)
def start_active_span_from_edu(
edu_content,
operation_name,
references=[],
tags=None,
start_time=None,
ignore_active_span=False,
finish_on_close=True,
):
"""
Extracts a span context from an edu and uses it to start a new active span
Args:
edu_content (dict): and edu_content with a `context` field whose value is
canonical json for a dict which contains opentracing information.
For the other args see opentracing.tracer
"""
if opentracing is None:
return _noop_context_manager()
carrier = json.loads(edu_content.get("context", "{}")).get("opentracing", {})
context = opentracing.tracer.extract(opentracing.Format.TEXT_MAP, carrier)
_references = [
opentracing.child_of(span_context_from_string(x))
for x in carrier.get("references", [])
]
# For some reason jaeger decided not to support the visualization of multiple parent
# spans or explicitely show references. I include the span context as a tag here as
# an aid to people debugging but it's really not an ideal solution.
references += _references
scope = opentracing.tracer.start_active_span(
operation_name,
child_of=context,
references=references,
tags=tags,
start_time=start_time,
ignore_active_span=ignore_active_span,
finish_on_close=finish_on_close,
)
scope.span.set_tag("references", carrier.get("references", []))
return scope
# Opentracing setters for tags, logs, etc
@only_if_tracing
def set_tag(key, value):
"""Sets a tag on the active span"""
opentracing.tracer.active_span.set_tag(key, value)
@only_if_tracing
def log_kv(key_values, timestamp=None):
"""Log to the active span"""
opentracing.tracer.active_span.log_kv(key_values, timestamp)
@only_if_tracing
def set_operation_name(operation_name):
"""Sets the operation name of the active span"""
opentracing.tracer.active_span.set_operation_name(operation_name)
# Injection and extraction
@only_if_tracing
def inject_active_span_twisted_headers(headers, destination):
"""
Injects a span context into twisted headers inplace
Injects a span context into twisted headers in-place
Args:
headers (twisted.web.http_headers.Headers)
span (opentracing.Span)
Returns:
Inplace modification of headers
In-place modification of headers
Note:
The headers set by the tracer are custom to the tracer implementation which
@ -437,7 +473,7 @@ def inject_active_span_byte_dict(headers, destination):
span (opentracing.Span)
Returns:
Inplace modification of headers
In-place modification of headers
Note:
The headers set by the tracer are custom to the tracer implementation which
@ -458,9 +494,190 @@ def inject_active_span_byte_dict(headers, destination):
headers[key.encode()] = [value.encode()]
@only_if_tracing
def inject_active_span_text_map(carrier, destination=None):
"""
Injects a span context into a dict
Args:
carrier (dict)
destination (str): the name of the remote server. The span context
will only be injected if the destination matches the homeserver_whitelist
or destination is None.
Returns:
In-place modification of carrier
Note:
The headers set by the tracer are custom to the tracer implementation which
should be unique enough that they don't interfere with any headers set by
synapse or twisted. If we're still using jaeger these headers would be those
here:
https://github.com/jaegertracing/jaeger-client-python/blob/master/jaeger_client/constants.py
"""
if destination and not whitelisted_homeserver(destination):
return
opentracing.tracer.inject(
opentracing.tracer.active_span, opentracing.Format.TEXT_MAP, carrier
)
def active_span_context_as_string():
"""
Returns:
The active span context encoded as a string.
"""
carrier = {}
if opentracing:
opentracing.tracer.inject(
opentracing.tracer.active_span, opentracing.Format.TEXT_MAP, carrier
)
return json.dumps(carrier)
@only_if_tracing
def span_context_from_string(carrier):
"""
Returns:
The active span context decoded from a string.
"""
carrier = json.loads(carrier)
return opentracing.tracer.extract(opentracing.Format.TEXT_MAP, carrier)
@only_if_tracing
def extract_text_map(carrier):
"""
Wrapper method for opentracing's tracer.extract for TEXT_MAP.
Args:
carrier (dict): a dict possibly containing a span context.
Returns:
The active span context extracted from carrier.
"""
return opentracing.tracer.extract(opentracing.Format.TEXT_MAP, carrier)
# Tracing decorators
def trace(func):
"""
Decorator to trace a function.
Sets the operation name to that of the function's.
"""
if opentracing is None:
return func
@wraps(func)
def _trace_inner(self, *args, **kwargs):
if opentracing is None:
return func(self, *args, **kwargs)
scope = start_active_span(func.__name__)
scope.__enter__()
try:
result = func(self, *args, **kwargs)
if isinstance(result, defer.Deferred):
def call_back(result):
scope.__exit__(None, None, None)
return result
def err_back(result):
scope.span.set_tag(tags.ERROR, True)
scope.__exit__(None, None, None)
return result
result.addCallbacks(call_back, err_back)
else:
scope.__exit__(None, None, None)
return result
except Exception as e:
scope.__exit__(type(e), None, e.__traceback__)
raise
return _trace_inner
def trace_using_operation_name(operation_name):
"""Decorator to trace a function. Explicitely sets the operation_name."""
def trace(func):
"""
Decorator to trace a function.
Sets the operation name to that of the function's.
"""
if opentracing is None:
return func
@wraps(func)
def _trace_inner(self, *args, **kwargs):
if opentracing is None:
return func(self, *args, **kwargs)
scope = start_active_span(operation_name)
scope.__enter__()
try:
result = func(self, *args, **kwargs)
if isinstance(result, defer.Deferred):
def call_back(result):
scope.__exit__(None, None, None)
return result
def err_back(result):
scope.span.set_tag(tags.ERROR, True)
scope.__exit__(None, None, None)
return result
result.addCallbacks(call_back, err_back)
else:
scope.__exit__(None, None, None)
return result
except Exception as e:
scope.__exit__(type(e), None, e.__traceback__)
raise
return _trace_inner
return trace
def tag_args(func):
"""
Tags all of the args to the active span.
"""
if not opentracing:
return func
@wraps(func)
def _tag_args_inner(self, *args, **kwargs):
argspec = inspect.getargspec(func)
for i, arg in enumerate(argspec.args[1:]):
set_tag("ARG_" + arg, args[i])
set_tag("args", args[len(argspec.args) :])
set_tag("kwargs", kwargs)
return func(self, *args, **kwargs)
return _tag_args_inner
def trace_servlet(servlet_name, func):
"""Decorator which traces a serlet. It starts a span with some servlet specific
tags such as the servlet_name and request information"""
if not opentracing:
return func
@wraps(func)
@defer.inlineCallbacks
@ -477,6 +694,44 @@ def trace_servlet(servlet_name, func):
},
):
result = yield defer.maybeDeferred(func, request, *args, **kwargs)
defer.returnValue(result)
defer.returnValue(result)
return _trace_servlet_inner
# Helper class
class _DummyTagNames(object):
"""wrapper of opentracings tags. We need to have them if we
want to reference them without opentracing around. Clearly they
should never actually show up in a trace. `set_tags` overwrites
these with the correct ones."""
INVALID_TAG = "invalid-tag"
COMPONENT = INVALID_TAG
DATABASE_INSTANCE = INVALID_TAG
DATABASE_STATEMENT = INVALID_TAG
DATABASE_TYPE = INVALID_TAG
DATABASE_USER = INVALID_TAG
ERROR = INVALID_TAG
HTTP_METHOD = INVALID_TAG
HTTP_STATUS_CODE = INVALID_TAG
HTTP_URL = INVALID_TAG
MESSAGE_BUS_DESTINATION = INVALID_TAG
PEER_ADDRESS = INVALID_TAG
PEER_HOSTNAME = INVALID_TAG
PEER_HOST_IPV4 = INVALID_TAG
PEER_HOST_IPV6 = INVALID_TAG
PEER_PORT = INVALID_TAG
PEER_SERVICE = INVALID_TAG
SAMPLING_PRIORITY = INVALID_TAG
SERVICE = INVALID_TAG
SPAN_KIND = INVALID_TAG
SPAN_KIND_CONSUMER = INVALID_TAG
SPAN_KIND_PRODUCER = INVALID_TAG
SPAN_KIND_RPC_CLIENT = INVALID_TAG
SPAN_KIND_RPC_SERVER = INVALID_TAG
tags = _DummyTagNames

2
synapse/logging/scopecontextmanager.py
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@ -131,7 +131,7 @@ class _LogContextScope(Scope):
def close(self):
if self.manager.active is not self:
logger.error("Tried to close a none active scope!")
logger.error("Tried to close a non-active scope!")
return
if self._finish_on_close: