---
name: rust-tracing
description: Add or change Rust diagnostic tracing in litellm-rust, including route spans, subscriber layers, and Python logger delivery
title: rust-tracing
canonical_url: https://skilld.dev/gh/berriai/litellm
last_updated: 2026-10-02T14:33:55.000Z
---

> Index of every page on this site: [llms.txt](https://skilld.dev/llms.txt)

> **Skill from skilld.dev.** Follow the user's requested action.
> If the user asked to fork this Skill, follow the fork workflow below. Do not execute the Skill instructions while copying it.
> Otherwise, follow the instructions below for this session. You do not need to install anything.
>
> If the user asked to install this Skill, run `npx skilld install berriai/litellm/rust-tracing`. Install writes the Skill files into the project, so every session loads them.
>
> ## Fork workflow
>
> A fork creates an editable local Skill with its original author and licence. The request authorizes copying and local installation.
> 1. Check `./skills/rust-tracing`, the project lockfile, and selected Agent targets together. If the local directory or installed Skill exists, stop. Never overwrite an existing directory or Agent target.
> 2. Read [source metadata](https://skilld.dev/api/v1/skills/berriai/litellm/rust-tracing) once. Use sourceUrl, sourceCommit, skillPath, sourceGone, and license. If the source is gone or its path is missing, stop. If license is null, read licence files at the source commit.
> 3. Fetch only the source commit into a temporary Git repository. Do not clone full history. Derive repository_url from sourceUrl, including repository renames. If sourceCommit is absent, resolve the sourceUrl ref once. Set source_commit to that actual commit. Run these commands in one shell call:
>
> ```sh
> git init --quiet "$temporary_dir"
> git -C "$temporary_dir" fetch --quiet --depth=1 "$repository_url" "$source_commit"
> git -C "$temporary_dir" checkout --quiet --detach FETCH_HEAD
> ```
>
> Read applicable licence declarations and notices at that commit. If copying is not permitted, report the restriction and stop.
> 4. Inspect source entries together, then copy the directory containing skillPath into `./skills/rust-tracing`. Use the user's path if selected. Keep the original SKILL.md, relative links, scripts, binary assets, and executable modes. Exclude .git metadata. Reject symlinks and paths outside the Skill directory. After checking entries, use cp -a where available. A regular source directory needs no custom copy script. Do not save this page wrapper as SKILL.md.
> Preserve author credit, notices, and applicable licence files from repository or parent directories. Add PROVENANCE.md with the Skill page, source URL, actual commit, original path, and licence. Retain any existing PROVENANCE.md and record new provenance separately. Batch source inspection, copying, and provenance work where practical.
> 5. In the project root, run `skilld install ./skills/rust-tracing --mode copy --plain`. If skilld is unavailable, use `npx skilld install ./skills/rust-tracing --mode copy --plain`. This known command needs no help lookup. Install does not support --json. Use detected Agent targets, or add --agent for the targets the user selected. Install the local path, never the upstream selector. If installation fails, preserve the local copy and report the exact failure.
> 6. Confirm the local lockfile source and installed Agent copies once. Report the local path, actual commit, and Agent targets. After edits, reinstall the same local path. Upstream updates must not replace it. Do not publish or push unless the user asks.

# Rust tracing

Use upstream `tracing` throughout Rust, including `#[tracing::instrument]`, events, and span propagation. Centralize collection and delivery infrastructure in `crates/tracing`. Direct upstream imports still reach our configured subscriber; re-exporting macros does not control delivery. Do not introduce Rust `log` or `pyo3-log` for this path

`litellm-tracing` owns shared subscriber layers, span field collection, and diagnostic processing. Keep adapters composable as `tracing_subscriber::Layer`s, with `Logger` providing host setup. Runtime-specific delivery belongs in the host bridge. The Python bridge delivers directly to the existing Python SDK logger, preserving its handlers, filtering, redaction, and request correlation. Keep Python dependencies out of `crates/tracing`

Hosts configure subscribers. Keep Python execution scoped to its captured dispatch rather than installing a process-wide subscriber. Propagate both span context and dispatch across spawned work and returned streams

In core, instrument execution shared by native calls and hosted machines. Use consistent route, model, provider, streaming, and outcome fields. Put status recording at shared provider boundaries instead of scattering basic logging through handlers. Keep upstream HTTP status separate from route success

Use `skip_all` and explicitly selected fields. Basic tracing excludes bodies, credentials, headers, and raw error strings. Avoid automatic `ret` or `err` capture of sensitive values. Keep payload diagnostics separate and subject to existing redaction

A returned stream retains its route span until exhaustion, error, or drop, with exactly one terminal outcome. Builder construction does not start a trace. Never hold a span entry guard across an await. Diagnostic tracing remains separate from lifecycle callbacks and `CustomLogger` dispatch

Use `litellm_tracing::sink_layer` to compose a sink with other subscriber layers. It inherits span fields into events and emits span-close summaries with elapsed time. Test observable records, concurrent isolation, dynamic filtering, sensitive-field exclusion, and stream cancellation when changing this behavior

Consult the [tracing API](https://docs.rs/tracing/latest/tracing/) and [subscriber layers](https://docs.rs/tracing-subscriber/latest/tracing_subscriber/layer/index.html) for implementation details