[ENH]: add tracing support for tokio console

[codetheweb]

Description of changes

Adds support for tokio-console to all services. This tool is useful when debugging, e.g. it should make it easy to see what futures are "stuck" / waiting on locks. It's disabled by default and can be enabled with an env var.

Test plan

How are these changes tested?

I port-forwarded 6669 from a service in Tilt to my host, then ran the tokio-console application and observed that data was flowing from the service to the tokio console.

Migration plan

Are there any migrations, or any forwards/backwards compatibility changes needed in order to make sure this change deploys reliably?

Observability plan

What is the plan to instrument and monitor this change?

Documentation Changes

Are all docstrings for user-facing APIs updated if required? Do we need to make documentation changes in the docs section?

[github-actions]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
• Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
• Should any logging, debugging, tracing information be added or removed?
• Are error messages user-friendly?
• Have all documentation changes needed been made?
• Have all non-obvious changes been commented?

System Compatibility

• Are there any potential impacts on other parts of the system or backward compatibility?
• Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[codetheweb]

my understanding of this flag is that it only enables opt-in features that are subject to change without corresponding semver changes

[codetheweb]

2 Jobs Failed:

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Summary: 1 successful workflow, 1 failed workflow

• ❌ PR checks (52 jobs succeeded, 2 jobs failed)
• ✅ Check PR Title (1 job succeeded)

Last updated: 2025-08-12 00:03:05 UTC

[propel-code-bot]

Add Tokio Console Tracing Support and Refactor Tracing Initialization

This PR adds support for the tokio-console tracing backend to all Rust services in the Chroma project. This enables runtime inspection and debugging of asynchronous tasks, such as identifying stuck futures or lock contention, by integrating the console-subscriber crate. The integration is gated by the ENABLE_TOKIO_CONSOLE environment variable, which opts services into exporting tracing data for the tokio-console application. The tracing initialization logic is refactored to bring tokio-console subscriber support under a single init_otel_tracing function, and dependency management is updated to ensure console-subscriber is available. Associated documentation, Docker build, and workspace build configurations are updated to support and build with these new features.

Key Changes

• Adds console-subscriber as a dependency in the workspace and to the chroma-tracing crate
• Introduces a new tracing initialization approach via init_otel_tracing that conditionally registers the tokio-console subscriber if ENABLE_TOKIO_CONSOLE is set
• Refactors all services to use the unified init_otel_tracing initialization (removing old function layering logic)
• Updates .cargo/config.toml to set rustflags = [--cfg, ``tokio_unstable``] globally, required for tokio-console support
• Updates Dockerfile and Tiltfile to include .cargo/ configs in build contexts for container builds
• Updates Cargo.lock to reflect new dependency versions and workspace-wide changes

Affected Areas

• Rust workspace dependency management (Cargo.toml, Cargo.lock)
• Tracing initialization in all Rust services (frontend, garbage_collector, chroma-tracing, etc.)
• Docker build process, Tiltfile local dev workflow, and Dockerfile dependency resolution
• Chroma-tracing crate API and usage
• .cargo/config.toml (Rust compiler flags)

This summary was automatically generated by @propel-code-bot

[HammadB]

should this be config? we don't really use env vars elsewhere but i could see it maybe being fine here. is this a standardized env var?

[codetheweb]

I don't have a strong preference
it's only standardized in the sense it's the same across all our services
common debug config loosely makes sense to me to have in env vars, but maybe we should just define a new common tracing config struct

[HammadB]

ok, in that case i would ask that it is config since our config system supports env var overrides, and having a single source of truth is preferable.

[HammadB]

does hosted/ depend on this code? It should be checked for dep issues, with a fix PR being up before this is merged

[HammadB]

is there any parent span that will actually capture this info?