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perf(docker): enable -Zshare-generics in the image build #845

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Merged
jlucaso1 merged 7 commits into from
Jun 11, 2026
Merged

perf(docker): enable -Zshare-generics in the image build #845

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5c2fcd6
perf(docker): enable -Zshare-generics in the image build
jlucaso1 Jun 11, 2026
f34d9d1
docker: copy the toolchain override into /app before the dependency cook
jlucaso1 Jun 11, 2026
7f7085f
docker: install cargo-chef with --locked
jlucaso1 Jun 11, 2026
12121ed
perf(docker): rebuild std with the release profile via build-std
jlucaso1 Jun 11, 2026
1489771
docker: pin cargo-chef to an exact version
jlucaso1 Jun 11, 2026
ac669a0
docker: derive the build target from the image host triple
jlucaso1 Jun 11, 2026
881b4b1
docker: fail fast if the host triple extraction comes up empty
jlucaso1 Jun 11, 2026
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27 changes: 22 additions & 5 deletions Dockerfile
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,8 @@
FROM rust:alpine AS chef
RUN apk add --no-cache musl-dev
COPY rust-toolchain.toml .
RUN rustup show && cargo install cargo-chef
# rust-src feeds -Zbuild-std in the builder stage.
RUN rustup show && rustup component add rust-src && cargo install cargo-chef --locked
WORKDIR /app

FROM chef AS planner
Expand All @@ -25,15 +26,31 @@ RUN cargo chef prepare --recipe-path recipe.json
# --- Builder: cook deps (cached layer), then compile source ---
FROM chef AS builder

ENV RUSTFLAGS="-C target-cpu=native"
# -Zshare-generics reuses upstream monomorphizations instead of re-codegening
# them per crate, deduplicating most cross-crate generic/coroutine copies
# (measured: -666 KiB, -5.6% .text). Nightly-only, which this image already
# pins via rust-toolchain.toml; with fat LTO the historical inlining downside
# does not apply since LTO sees all bitcode anyway.
ENV RUSTFLAGS="-C target-cpu=native -Zshare-generics=y"
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# build-std recompiles std with the release profile so it participates in fat
# LTO and dead-code elimination instead of linking the prebuilt rustup std
# (measured: another -303 KiB). The env form reaches both the chef cook and
# the final build, keeping the dependency cache layer valid; build-std
# requires an explicit --target, hence the musl triple on both invocations.
ENV CARGO_UNSTABLE_BUILD_STD="std,panic_abort"

# The dependency cook runs before the source COPY, so make the nightly
# override explicit in /app instead of relying on rustup walking up to the
# chef stage's copy at /; the nightly-only RUSTFLAGS above depends on it.
COPY rust-toolchain.toml .
COPY --from=planner /app/recipe.json recipe.json
RUN cargo chef cook --release --recipe-path recipe.json
RUN cargo chef cook --release --recipe-path recipe.json --target x86_64-unknown-linux-musl
COPY . .
RUN cargo build --release
RUN cargo build --release --target x86_64-unknown-linux-musl
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# --- Runtime: static binary on empty image ---
FROM scratch
COPY --from=builder /app/target/release/whatsapp-rust /whatsapp-rust
COPY --from=builder /app/target/x86_64-unknown-linux-musl/release/whatsapp-rust /whatsapp-rust
WORKDIR /data
ENTRYPOINT ["/whatsapp-rust"]
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