OT Bridge - Initial implementation #6

johananl · 2019-10-04T18:47:38Z

This is an initial implementation of the OpenTracing bridge following received feedback on open-telemetry#120. The bridge is an implementation of the OpenTracing Tracer class and includes several other OpenTracing subclasses required for implementing the tracer.

The following pieces are still not implemented:

Inject/extract methods.
Baggage items.

To run the unit tests, use the following:

git clone git@github.com:kinvolk/opentelemetry-python.git
cd opentelemetry-python
git checkout johananl/ot-shim
virtualenv /tmp/venv
source /tmp/venv/bin/activate
pip install tox
tox

To test actual tracing, use the following:

git clone git@github.com:kinvolk/opentelemetry-python.git
cd opentelemetry-python
git checkout johananl/ot-shim
virtualenv /tmp/venv
source /tmp/venv/bin/activate
cd opentracing-shim
python setup.py install
pip install opentelemetry-sdk

Then instrument an app:

import time
from opentelemetry.sdk.trace import Tracer, export
from opentelemetry.sdk.trace.export.in_memory_span_exporter import InMemorySpanExporter
from opentracingshim import create_tracer

otel_tracer = Tracer()
memory_exporter = InMemorySpanExporter()
span_processor = export.SimpleExportSpanProcessor(memory_exporter)
otel_tracer.add_span_processor(span_processor)

tracer = create_tracer(otel_tracer)

print('------------Started------------')

with tracer.start_active_span('parent') as parent:
    time.sleep(1)
    with tracer.start_active_span('child') as child:
        time.sleep(2)

for s in memory_exporter.get_finished_spans():
    print(s)
    print(s.get_context())

print('-------------Done--------------')

krnowak

Two comments. But I'm not very well informed in the python stuff.

opentracing-shim/src/opentracingshim/__init__.py

mauriciovasquezbernal

General implementation looks very good, just minor comments.

What is the best approach for unimplemented methods? Do nothing or raise?
I'm not totally sure I fully understand the details of Handle "mixed mode" OT/OTel tracing in OT Bridge open-telemetry/opentelemetry-python#161. Will look into detail/ask you later on.

opentracing-shim/README.rst

opentracing-shim/src/opentracingshim/__init__.py

opentracing-shim/setup.py

opentracing-shim/src/opentracingshim/__init__.py

mauriciovasquezbernal · 2019-10-04T20:32:25Z

opentracing-shim/src/opentracingshim/__init__.py

+        start_time=None,
+        ignore_active_span=False,
+    ) -> SpanWrapper:
+        parent = child_of


Is this line really needed?

It saves me from having to specify the else clause. I like this as it's more compact and less indented.
Please feel free to suggest an alternative (we need to allow parent to be None).

You're totally right. I didn't consider one of the ifs.

opentracing-shim/src/opentracingshim/__init__.py

opentracing-shim/tests/test_shim.py

johananl · 2019-10-04T22:39:49Z

opentracing-shim/src/opentracingshim/util.py

+        return int(time.time() * 1e9)
+
+
+# A default event name to be used when logging events when a better event name


Suggested change

# A default event name to be used when logging events when a better event name

# A default event name to be used for logging events when a better event name

johananl · 2019-10-04T22:42:13Z

opentracing-shim/tests/test_shim.py

+            # Verify span hasn't ended.
+            self.assertIsNone(scope.span.unwrap().end_time)
+
+        # Verify span hasn't ended.


Suggested change

# Verify span hasn't ended.

# Verify span hasn't ended after scope had been closed.

opentracing-shim/src/opentracingshim/__init__.py

Add missing stubs for fully implementing the Span and Scope classes from OpenTracing.

- Explicitly use opentracing.* to make OpenTracing imports easily distinguishable. - Leave OpenTelemetry class names as-is.

Since start_span() is a context manager and since we want the OpenTelemetry Span to stop when the SpanWrapper stops, we need to turn start_active_span() into a context manager and yield the ScopeWrapper rather than return it.

Due to the differences between decimal and binary float representations, some time values yield "surprising" results when performing float arithmetic operations to convert seconds to nanoseconds and vice versa.

"ot" isn't clear enough and could lead to confusion.

If the user passes a custom ScopeManager, we want the TracerWrapper to call `active_span` on the custom ScopeManager.

Log a warning instead in order not to break application code.

Let the OTel implementation create event timestamps instead of generating a timestamp in the shim, i.e. outside of OpenTelemetry.

- Remove an unnecessary context manager layers. - Allow creating `ContextWrapper` objects either from a `SpanWrapper` or from a `Span` context manager.

Until we figure out how to handle unsupported frameworks (e.g. gevent), we remove the `scope_manager` argument of `create_tracer` to avoid breaking the OpenTelemetry context propagation.

These are obvious and therefore unnecessary.

The API docs are clear about the `references` argument being a list. We don't try to compensate for wrong argument types elsewhere, so no reason to do that here.

Not all classes in the shim are actually wrappers, which makes the XWrapper naming convention confusing. XShim is more neutral.

In the OpenTracing API, when an exception occurs while a span is active, information about the exception is added to the span as logs and a tag is added as well. We re-add this functionality to the shim since we've overridden the `__exit__()` method in which it lives.

Validating the parent type complicates the logic of `start_span()`. Since the OpenTracing API clearly specifies the valid types for a parent span, it's the user's responsibility to specify a valid parent.

Verify that calling `close()` on a `ScopeShim` deactivates the span in the OpenTelemetry tracer.

We shouldn't return OpenTelemetry objects to the OpenTracing API.

Make it clearer that the provided tracer object should be an OpenTelemetry tracer, not an OpenTracing tracer.

johananl requested review from alban, krnowak and mauriciovasquezbernal October 4, 2019 18:47

krnowak reviewed Oct 4, 2019

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mauriciovasquezbernal reviewed Oct 4, 2019

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johananl commented Oct 4, 2019

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johananl commented Oct 4, 2019

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johananl force-pushed the johananl/ot-shim branch 2 times, most recently from e60e605 to e3ce0fd Compare October 7, 2019 14:54

mauriciovasquezbernal reviewed Oct 7, 2019

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johananl force-pushed the johananl/ot-shim branch 8 times, most recently from c42ff3d to 564cc0e Compare October 14, 2019 16:34

johananl force-pushed the johananl/ot-shim branch from d6e82bc to 665747c Compare October 18, 2019 19:45

johananl added 10 commits October 23, 2019 15:59

Add OpenTracing shim package skeleton

3e495b9

Test OT shim

18a71c1

Rename wrapper classes

4745eca

Add missing stubs

16d5126

Add missing stubs for fully implementing the Span and Scope classes from OpenTracing.

Return an initialized ScopeWrapper

ebfbcd2

Add TODO

fea256c

Test setting span name

ad0ac64

Run black

3830cfc

Re-organize imports

564c1f2

- Explicitly use opentracing.* to make OpenTracing imports easily distinguishable. - Leave OpenTelemetry class names as-is.

Make start_active_span() a context manager

bb72218

Since start_span() is a context manager and since we want the OpenTelemetry Span to stop when the SpanWrapper stops, we need to turn start_active_span() into a context manager and yield the ScopeWrapper rather than return it.

johananl added 13 commits October 23, 2019 18:32

Handle inaccuracies in time conversions

8fd39ef

Due to the differences between decimal and binary float representations, some time values yield "surprising" results when performing float arithmetic operations to convert seconds to nanoseconds and vice versa.

Move OpenTracing shim under ext dir

9453625

Rename package to opentelemetry-opentracing-shim

78183cc

"ot" isn't clear enough and could lead to confusion.

Call init on super before setting own attributes

4f88e7c

Don't override active_span on TracerWrapper

8a7c1a7

If the user passes a custom ScopeManager, we want the TracerWrapper to call `active_span` on the custom ScopeManager.

Refactor handling of invalid parent type

cbe971b

Don't raise on unimplemented methods

97f3734

Log a warning instead in order not to break application code.

Allow passing a timestamp to add_event()

0017eee

Let the OTel implementation create event timestamps

c644c10

Let the OTel implementation create event timestamps instead of generating a timestamp in the shim, i.e. outside of OpenTelemetry.

Refactor scope handling

55e692a

- Remove an unnecessary context manager layers. - Allow creating `ContextWrapper` objects either from a `SpanWrapper` or from a `Span` context manager.

Remove opentracing runtime dependency from tox.ini

9210853

Clean up test setup

cb41689

Rename package to opentracing_shim

04d44e3

johananl force-pushed the johananl/ot-shim branch from 39c1d80 to 8b00729 Compare October 23, 2019 16:35

johananl added 14 commits October 23, 2019 21:01

Don't allow using arbitrary scope managers

add02e7

Until we figure out how to handle unsupported frameworks (e.g. gevent), we remove the `scope_manager` argument of `create_tracer` to avoid breaking the OpenTelemetry context propagation.

Remove unnecessary comments.

c2b03a7

These are obvious and therefore unnecessary.

Remove TODO

ecfd2b8

Don't accept scalar values in references argument

3a78b2c

The API docs are clear about the `references` argument being a list. We don't try to compensate for wrong argument types elsewhere, so no reason to do that here.

Rename XWrapper to XShim

10f72ac

Not all classes in the shim are actually wrappers, which makes the XWrapper naming convention confusing. XShim is more neutral.

Don't call active_span() when we have a parent

aee40a3

Refactor ScopeShim

f093ee1

Don't validate parent type

1f4cc3c

Validating the parent type complicates the logic of `start_span()`. Since the OpenTracing API clearly specifies the valid types for a parent span, it's the user's responsibility to specify a valid parent.

Verify ScopeShim.close() deactivates span

970ce6a

Verify that calling `close()` on a `ScopeShim` deactivates the span in the OpenTelemetry tracer.

Wrap span context properly

fc12138

We shouldn't return OpenTelemetry objects to the OpenTracing API.

Refactor ScopeShim initializers

fc6f34e

Add TODO

7860f55

Rename tracer argument of create_tracer()

082183a

Make it clearer that the provided tracer object should be an OpenTelemetry tracer, not an OpenTracing tracer.

johananl force-pushed the johananl/ot-shim branch from 81b59ed to 082183a Compare October 23, 2019 19:04

johananl closed this Nov 18, 2019

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OT Bridge - Initial implementation #6

OT Bridge - Initial implementation #6

johananl commented Oct 4, 2019 •

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johananl Oct 4, 2019

johananl Oct 4, 2019

		return int(time.time() * 1e9)


		# A default event name to be used when logging events when a better event name

	# A default event name to be used when logging events when a better event name
	# A default event name to be used for logging events when a better event name

	# Verify span hasn't ended.
	# Verify span hasn't ended after scope had been closed.

OT Bridge - Initial implementation #6

OT Bridge - Initial implementation #6

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