Rust Deploy

Rust Deployment

Detection

Project is Rust if Cargo.toml or cargo.toml exists.

Versions

Rust version priority:

1. rust-toolchain.toml → toolchain.channel
2. Cargo.toml → package.rust-version
3. .rust-version file
4. Cargo.toml → package.edition (maps to minimum Rust version)
5. Defaults to latest stable (1.89)

Build

Build Command

• cargo build --release
• Binary: target/release/<package-name>
• Package name from Cargo.toml → [package].name

Entry Resolution

1. Binary crate: src/main.rs
2. Multi-binary: src/bin/<name>.rs → binary name matches filename
3. Library + binary: [bin] section in Cargo.toml

Output

• Build output: target/release/<name>
• Start command: ./bin/<project-name> or ./target/release/<name>

Runtime Variables

Port Detection

1. PORT in .env / .env.example
2. Source code patterns: :8080, bind, TcpListener in main.rs
3. Default: 8080

Framework / Library Detection

Install Stage Optimization

Copy in order:

• Cargo.toml, Cargo.lock
• src/ (or full source)

BuildKit Caching

Base Images

For Alpine build: may need musl-dev for fully static binary.

Dockerfile Patterns

Multi-Stage (Debian)

FROM rust:1.89-bookworm AS build
WORKDIR /app
COPY Cargo.toml Cargo.lock ./
RUN mkdir src && echo "fn main() {}" > src/main.rs
RUN cargo build --release
COPY src ./src
RUN touch src/main.rs && cargo build --release

FROM debian:bookworm-slim
RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/lib/apt/lists/*
WORKDIR /app
COPY --from=build /app/target/release/<binary-name> .
EXPOSE 8080
CMD ["./<binary-name>"]

Cargo Chef (faster layer cache)

FROM rust:1.89-bookworm AS chef
RUN cargo install cargo-chef

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

FROM chef AS build
WORKDIR /app
COPY --from=planner /app/recipe.json .
RUN cargo chef cook --release --recipe-path recipe.json
COPY . .
RUN cargo build --release

FROM debian:bookworm-slim
RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/lib/apt/lists/*
WORKDIR /app
COPY --from=build /app/target/release/<binary-name> .
EXPOSE 8080
CMD ["./<binary-name>"]

Simple (no chef)

FROM rust:1.89-bookworm AS build
WORKDIR /app
COPY . .
RUN cargo build --release

FROM debian:bookworm-slim
RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/lib/apt/lists/*
WORKDIR /app
COPY --from=build /app/target/release/<binary-name> .
EXPOSE 8080
CMD ["./<binary-name>"]

Gotchas

• The dummy main.rs trick (echo "fn main() {}" > src/main.rs) caches dependency compilation, but touch src/main.rs is needed afterward to invalidate the binary build cache
• Cargo.lock must be committed for binary crates — without it, dependency versions are resolved fresh on every build
• Alpine builds need musl-dev, but crates using OpenSSL also need openssl-dev and pkgconfig
• Rust builds are memory-intensive — cargo build --release -j 2 limits parallelism to avoid OOM kills in resource-constrained environments
• Cargo chef prepare requires the full source tree — it scans code to compute the dependency recipe