---
title: sandbox_id
summary: A UUID generated by Fastly for each sandbox.
url: https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/compute_runtime/fn.sandbox_id/
---

**Kind:** Function  
**Module:** [compute_runtime](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/compute_runtime/)  
**Package:** fastly 0.13.1  
**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/compute_runtime.rs#254

```rust
fn sandbox_id() -> &'static str
```

A UUID generated by Fastly for each sandbox.

This is often a useful value to include in log messages, and also to send to upstream
servers as an additional custom HTTP header, allowing for straightforward correlation of
which WebAssembly session processed a request to requests later processed by an origin
server. If a session is used to process multiple downstream requests, then you may wish to
use the per-request UUID associated with each individual request handle instead of this
function.

Equivalent to the "FASTLY_TRACE_ID" environment variable.

**Returns**

`&str`