Supported crates

Background

Learn about popular Rust crates which have been confirmed to work on Workers when using workers-rs ↗ (or in some cases just wasm-bindgen), to write Workers in WebAssembly. Each Rust crate example includes any custom configuration that is required.

This is not an exhaustive list, many Rust crates can be compiled to the wasm32-unknown-unknown ↗ target that is supported by Workers. In some cases, this may require disabling default features or enabling a Wasm-specific feature. It is important to consider the addition of new dependencies, as this can significantly increase the size of your Worker.

time

Many crates which have been made Wasm-friendly, will use the time crate instead of std::time. For the time crate to work in Wasm, the wasm-bindgen feature must be enabled to obtain timing information from JavaScript.

tracing

Tracing can be enabled by using the tracing-web crate and the time feature for tracing-subscriber. Due to timing limitations on Workers, spans will have identical start and end times unless they encompass I/O.

Refer to the tracing example ↗ for more information.

reqwest

The reqwest library ↗ can be compiled to Wasm, and hooks into the JavaScript fetch API automatically using wasm-bindgen.

tokio-postgres

tokio-postgres can be compiled to Wasm. It must be configured to use a Socket from workers-rs:

Refer to the tokio-postgres example ↗ for more information.

hyper

The hyper crate contains two HTTP clients, the lower-level conn module and the higher-level Client. The conn module can be used with Workers Socket, however Client requires timing dependencies which are not yet Wasm friendly.

Refer to the hyper example ↗ for more information.