fix(bedrock): handle non-text contentBlockDelta events in converse_stream

[octavifs]

• I have added tests that cover my changes.
• If adding a new instrumentation or changing an existing one, I've added screenshots from some observability platform showing the change.
• PR name follows conventional commits format: feat(instrumentation): ... or fix(instrumentation): ....
• (If applicable) I have updated the documentation accordingly.

---

Fixes #2961

This PR fixes the KeyError when using the bedrock converse api with streaming, on events other than text, and adds a test to validate the fix for handling non-text contentBlockDelta events in Bedrock's converse_stream API.

Background

According to AWS Bedrock API documentation, the contentBlockDelta field can contain EITHER of the following:

• citation
• reasoningContent
• toolUse
• text

The previous code assumed text would always be present, causing KeyError exceptions when the model uses tools or returns other content types.

Changes

• Fixes KeyError on contentBlockDelta containing attributes other than "text"
• Add test_anthropic_converse_stream_with_tool_use in test_anthropic.py
• Record VCR cassette with tool use interaction (cleaned of credentials)

Test Details

The new test:

1. Sends a weather query with a get_weather tool definition
2. Streams the response which triggers the model to use the tool
3. Validates that contentBlockDelta events with toolUse (instead of text) don't crash the instrumentation
4. Ensures proper span recording throughout

Related

• Issue: 🐛 Bug Report: #2961

---

Important

Fixes KeyError in converse_stream by handling non-text contentBlockDelta events and adds a test to validate the fix.

• Behavior:
  • Fixes KeyError in converse_stream in __init__.py by checking for 'text' in contentBlockDelta events.
  • Handles non-text events like toolUse without crashing.
• Tests:
  • Adds test_anthropic_converse_stream_with_tool_use in test_anthropic.py to validate handling of non-text contentBlockDelta events.
  • Uses a VCR cassette test_anthropic_converse_stream_with_tool_use.yaml to simulate tool use interaction.
• Misc:
  • Ensures proper span recording and no logs emitted when use_legacy_attributes is True.

^{This description was created by for d511cd6. You can customize this summary. It will automatically update as commits are pushed.}

Summary by CodeRabbit

• Bug Fixes

  • Improved stability of Anthropic streaming by only accumulating text when present in content deltas, preventing errors from missing or non-text events.
  • Strengthened handling of tool use during streaming to avoid crashes and ensure smooth response processing.

• Tests

  • Added coverage for Anthropic converse streaming with tool use, including a new cassette.
  • Validates non-text event handling and expected tracing attributes/spans without legacy logs.

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• packages/opentelemetry-instrumentation-bedrock/tests/traces/test_anthropic.py (1 hunks)

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Walkthrough

Adds a guard in Bedrock instrumentation to append streaming text only when present in contentBlockDelta.delta.text. Introduces a new test for Anthropic converse_stream with tool use and a corresponding cassette, validating handling of non-text deltas and ensuring spans and attributes are recorded.

Changes

Cohort / File(s)	Summary
Bedrock streaming guard packages/opentelemetry-instrumentation-bedrock/opentelemetry/instrumentation/bedrock/__init__.py	Tightens condition in _handle_converse_stream to append to response only when event.contentBlockDelta.delta.text exists.
Tests: Anthropic converse_stream with tool use packages/opentelemetry-instrumentation-bedrock/tests/traces/test_anthropic.py	Adds test to iterate stream, collect text deltas when present, detect toolUse deltas, and assert span attributes and absence of legacy logs.
Cassettes: Anthropic tool-use stream packages/opentelemetry-instrumentation-bedrock/tests/traces/cassettes/test_anthropic/test_anthropic_converse_stream_with_tool_use.yaml	Adds VCR cassette capturing Bedrock runtime POST with toolConfig and event-stream response for weather tool invocation.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  actor Test as Test
  participant Client as Bedrock Runtime Client
  participant Bedrock as Bedrock Service
  participant Instr as Instrumentation

  rect rgb(240,245,255)
    Test->>Client: converse_stream(request with toolConfig)
    Client->>Bedrock: HTTP POST /model/... (stream)
    Bedrock-->>Client: EventStream (contentBlockDelta / toolUse / text / ...)

    loop For each event
      Client-->>Instr: on_event(event)
      alt Has contentBlockDelta.delta.text
        Instr->>Instr: append text to response_msg
      else Non-text delta (e.g., toolUse)
        Instr->>Instr: skip text accumulation
      end
    end
  end

  Client-->>Test: Stream iteration completes
  Instr-->>Instr: record span with model/vendor/request type
  note over Instr: No legacy attributes logs emitted

Loading

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested reviewers

• nirga
• doronkopit5
• dinmukhamedm

Poem

I twitch my ears at streaming breeze,
Guarding text from missing keys.
Tools may chatter, clouds may brew—
I nibble deltas, only true.
Traces hop, spans neatly align,
Bugs burrow out, the carrots shine. 🥕🐇

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 16.67% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title succinctly describes the primary change by indicating a bug fix in the Bedrock instrumentation’s converse_stream to handle non-text contentBlockDelta events, accurately reflecting the code update without extraneous detail.
Linked Issues Check	✅ Passed	The changes fully implement the fix described in issue #2961 by adding the necessary checks for “delta” and “text” within contentBlockDelta to prevent KeyErrors, and the added test reproduces and validates handling of toolUse events as specified.
Out of Scope Changes Check	✅ Passed	All modified files and tests directly relate to fixing the KeyError in converse_stream and validating non-text contentBlockDelta events; there are no unrelated or extraneous code changes in this PR.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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[ellipsis-dev]

Important

Looks good to me! 👍

Reviewed everything up to d511cd6 in 47 seconds. Click for details.

• Reviewed 248 lines of code in 3 files
• Skipped 0 files when reviewing.
• Skipped posting 2 draft comments. View those below.
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1. packages/opentelemetry-instrumentation-bedrock/opentelemetry/instrumentation/bedrock/__init__.py:391

• Draft comment:
  Nice fix: the updated conditional checks if the 'delta' field contains a 'text' key before appending, which prevents KeyError on non-text contentBlockDelta events. This aligns with the AWS Bedrock API documentation.
• Reason this comment was not posted:
  Comment did not seem useful. Confidence is useful = 0% <= threshold 50% This comment is purely informative, as it praises the fix and explains what it does without suggesting any changes or improvements. It doesn't ask for confirmation or suggest any specific action.

2. packages/opentelemetry-instrumentation-bedrock/tests/traces/test_anthropic.py:980

• Draft comment:
  The new test 'test_anthropic_converse_stream_with_tool_use' effectively validates that non-text (e.g. toolUse) events do not crash the instrumentation and correctly set span attributes. This improves coverage of edge cases.
• Reason this comment was not posted:
  Comment did not seem useful. Confidence is useful = 0% <= threshold 50% This comment is purely informative, describing what the new test does and its benefits. It doesn't provide any actionable feedback or suggestions for improvement.

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[nirga]

Thanks @octavifs!

[octavifs]

You're welcome!
Thanks to you guys for running the project!