Add Support for Detecting Synthetic Source

[JacksonWeber]

Description

This pull request introduces experimental support for detecting synthetic traffic (such as bots and test monitors) in the OpenTelemetry Requests instrumentation by analyzing the User-Agent header. It adds logic to classify requests as originating from bots or test systems, sets a corresponding span attribute, and includes comprehensive tests to validate this behavior.

The most important changes are:

Synthetic User Agent Detection and Span Attributes:

• Added a function _detect_synthetic_user_agent in __init__.py to analyze the User-Agent header and classify requests as either "bot" or "test" traffic, prioritizing test patterns over bot patterns.
• Set the user_agent.synthetic.type span attribute when a synthetic user agent is detected, using new constants for attribute name and possible values. [1] [2]

Semantic Conventions:

• Introduced a new module semconv.py defining experimental semantic convention constants for synthetic user agent detection, including ATTR_USER_AGENT_SYNTHETIC_TYPE, USER_AGENT_SYNTHETIC_TYPE_VALUE_BOT, and USER_AGENT_SYNTHETIC_TYPE_VALUE_TEST.
• Updated imports in __init__.py to use these new constants from semconv.py.

Testing:

• Added a comprehensive test suite in test_user_agent_synthetic.py to verify detection logic for various user agent scenarios, including bots, test agents, normal browsers, case insensitivity, substring matches, and pattern priority.

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Tested via unit tests included in test_user_agent_synthetic.py

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[xrmx]

Since there's nothing requests specific here I think this should go into opentelemetry-util-http instead. Said that I'm not sure we should ship our own experimental semantic conventions. I don't see any PR in the semantic-conventions repo adding this stuff, so could you please elaborate a bit what's your plan?

[xrmx]

Since there's nothing requests specific here I think this should go into opentelemetry-util-http instead. Said that I'm not sure we should ship our own experimental semantic conventions. I don't see any PR in the semantic-conventions repo adding this stuff, so could you please elaborate a bit what's your plan?

So I had seen this PR in semconv repo open-telemetry/semantic-conventions#1523 before writing that comment but I only read the PR description with an old attribute name and not the title with the updated one that matches this. So since we already have the attribute in the semconv since a few (https://github.com/open-telemetry/opentelemetry-python/blob/05343a5c8848f5f55a69100a0becf61766b33051/opentelemetry-semantic-conventions/src/opentelemetry/semconv/_incubating/attributes/user_agent_attributes.py#L41) we should just import it from there and not opencode it.

[JacksonWeber]

Since there's nothing requests specific here I think this should go into opentelemetry-util-http instead. Said that I'm not sure we should ship our own experimental semantic conventions. I don't see any PR in the semantic-conventions repo adding this stuff, so could you please elaborate a bit what's your plan?

1. This PR does only add this functionality to requests, however I'm happy to move these changes over to opentelemetry-util-http if that'd be more appropriate
2. Addressing this on your other comment.

[JacksonWeber]

Since there's nothing requests specific here I think this should go into opentelemetry-util-http instead. Said that I'm not sure we should ship our own experimental semantic conventions. I don't see any PR in the semantic-conventions repo adding this stuff, so could you please elaborate a bit what's your plan?

So I had seen this PR in semconv repo open-telemetry/semantic-conventions#1523 before writing that comment but I only read the PR description with an old attribute name and not the title with the updated one that matches this. So since we already have the attribute in the semconv since a few (https://github.com/open-telemetry/opentelemetry-python/blob/05343a5c8848f5f55a69100a0becf61766b33051/opentelemetry-semantic-conventions/src/opentelemetry/semconv/_incubating/attributes/user_agent_attributes.py#L41) we should just import it from there and not opencode it.

Thanks for the point out here, the guidance in OTel JS works a bit differently (they ask to hard-code these kinds of experimental semantic conventions in order to avoid breaking customers using the old experimental attributes). I'll update these imports.