cargo-chef

Table of Contents

1. How to install
2. How to use
3. Benefits vs Limitations
4. License

How To Install

You can install

cargo-chef

cargo install cargo-chef

How to use

:warning: cargo-chef is not meant to be run locally
Its primary use-case is to speed up container builds by running BEFORE the actual source code is copied over. Don't run it on existing codebases to avoid having files being overwritten.

cargo-chef

prepare

cook

cargo chef --help

cargo-chef

USAGE:
    cargo chef 
SUBCOMMANDS:
    cook       Re-hydrate the minimum project skeleton identified by cargo chef prepare and
               build it to cache dependencies
    prepare    Analyze the current project to determine the minimum subset of files (Cargo.lock
               and Cargo.toml manifests) required to build it and cache dependencies

prepare

cargo chef prepare --recipe-path recipe.json

Nothing too mysterious going on here, you can examine the

recipe.json

Cargo.toml

Cargo.lock

Cargo.toml

src/main.rs

src/lib.rs

The

recipe.json

requirements.txt

cargo chef cook

cargo chef cook --recipe-path recipe.json

If you want to build in

--release

cargo chef cook --release --recipe-path recipe.json

You can leverage it in a Dockerfile:

FROM lukemathwalker/cargo-chef as planner
WORKDIR app
COPY . .
RUN cargo chef prepare  --recipe-path recipe.json

FROM lukemathwalker/cargo-chef as cacher
WORKDIR app
COPY --from=planner /app/recipe.json recipe.json
RUN cargo chef cook --release --recipe-path recipe.json
FROM rust as builder
WORKDIR app
COPY . .
Copy over the cached dependencies
COPY --from=cacher /app/target target
COPY --from=cacher $CARGO_HOME $CARGO_HOME
RUN cargo build --release --bin app
FROM rust as runtime
WORKDIR app
COPY --from=builder /app/target/release/app /usr/local/bin
ENTRYPOINT ["/usr/local/bin/app"]

We are using four stages: the first computes the recipe file, the second caches our dependencies, the third builds the binary and the fourth is our runtime environment.
As long as your dependencies do not change the

recipe.json

cargo cargo chef cook --release --recipe-path recipe.json

If you do not want to use the

lukemathwalker/cargo-chef

FROM rust as planner
WORKDIR app
# We only pay the installation cost once, 
# it will be cached from the second build onwards
RUN cargo install cargo-chef 
COPY . .
RUN cargo chef prepare  --recipe-path recipe.json

FROM rust as cacher
WORKDIR app
RUN cargo install cargo-chef
COPY --from=planner /app/recipe.json recipe.json
RUN cargo chef cook --release --recipe-path recipe.json
FROM rust as builder
WORKDIR app
COPY . .
Copy over the cached dependencies
COPY --from=cacher /app/target target
COPY --from=cacher $CARGO_HOME $CARGO_HOME
RUN cargo build --release --bin app
FROM rust as runtime
WORKDIR app
COPY --from=builder /app/target/release/app /usr/local/bin
ENTRYPOINT ["/usr/local/bin/app"]

Benefits vs Limitations

cargo-chef

cargo build

Benefits of

cargo-chef

:

A common alternative is to load a minimal

main.rs

Cargo.toml

Cargo.lock

cargo-chef

• automatically pick up all crates in a workspace (and new ones as they are added)
• keep working when files or crates are moved around, which would instead require manual edits to the

  Dockerfile

  using the "manual" approach
• generate fewer intermediate Docker layers (for workspaces)

Limitations and caveats:

• cargo cook

  and

  cargo build

  must be executed from the same working directory. If you examine the

  *.d

  files under

  target/debug/deps

  for one of your projects using

  cat

  you will notice that they contain absolute paths referring to the project

  target

  directory. If moved around,

  cargo

  will not leverage them as cached dependencies;

• cargo build

  will build local dependencies (outside of the current project) from scratch, even if they are unchanged, due to the reliance of its fingerprinting logic on timestamps (see this long issue on

  cargo

  's repository);

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option. Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.