Remove unused tracing dependency from opentelemetry-otlp

[Copilot]

The opentelemetry-otlp crate declared tracing as a direct dependency but never used it in its source code. The dependency was only needed transitively via opentelemetry and opentelemetry_sdk when their internal-logs features are enabled.

Changes

• Removed direct tracing dependency from opentelemetry-otlp/Cargo.toml
• Updated internal-logs feature to only pass through to opentelemetry and opentelemetry_sdk:

  # Before
  internal-logs = ["tracing", "opentelemetry_sdk/internal-logs", "opentelemetry/internal-logs"]
  
  # After
  internal-logs = ["opentelemetry_sdk/internal-logs", "opentelemetry/internal-logs"]

The tracing crate remains available when internal-logs is enabled through transitive dependencies. No functional or API changes.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Refactor internal-logs feature in opentelemetry-otlp to reduce unnecessary dependencies</issue_title>
<issue_description>

Discussed in #3191

^{Originally posted by houseme October 3, 2025}

Summary

The internal-logs feature in the opentelemetry-otlp crate currently enables "opentelemetry-http/internal-logs". However, since opentelemetry-http itself depends on "opentelemetry/internal-logs", this indirection introduces an unnecessary dependency on opentelemetry-http when using grpc-tonic without default or http features.

Current Behavior

In opentelemetry-otlp/Cargo.toml:

[features]
internal-logs = ["tracing", "opentelemetry_sdk/internal-logs", "opentelemetry-http/internal-logs"]

This forces users to depend on opentelemetry-http even when:

• Using grpc-tonic transport
• Not using http or default features
• Only needing internal-logs functionality

Proposed Change

Directly depend on "opentelemetry/internal-logs" instead:

[features]
internal-logs = ["tracing", "opentelemetry_sdk/internal-logs", "opentelemetry/internal-logs"]

Benefits

1. Eliminates unnecessary dependencies
   Removes forced opentelemetry-http dependency for grpc-tonic users
2. Aligns with dependency hierarchy
   Since opentelemetry-http already depends on opentelemetry/internal-logs, this change respects the existing dependency chain
3. Improves compile times
   Particularly for projects using grpc-tonic with default-features = false
4. Maintains compatibility
   No breaking changes - all existing functionality preserved

Verification Steps

1. Check opentelemetry-http/Cargo.toml confirms:

   [features]
   internal-logs = ["opentelemetry/internal-logs"]

2. Test with:

   opentelemetry-otlp = { version = "*", default-features = false, features = ["grpc-tonic", "internal-logs"] }

   Should not pull opentelemetry-http

Additional Context

This micro-optimization supports the project's goal of maintaining a lean dependency tree, especially important for users carefully managing their dependency footprint in performance-sensitive applications.

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Would you like me to submit a PR for this change?
I can prepare a minimal PR updating the feature flag if the maintainers agree this is a welcome optimization.

cc @lalitb @bantonsson

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Refactor internal-logs feature in opentelemetry-otlp to reduce unnecessary dependencies #3263

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