具有 2 个入口点的 Dockerfile

Question

我正在学习docker，特别是如何编写docker文件。最近我遇到了这个，不明白为什么里面有 2 个ENTRYPOINT 。

原始文件位于此链接CosmWasm/rust-optimizer Dockerfile中。下面的代码是其当前的实际内容。

FROM rust:1.60.0-alpine as targetarch

ARG BUILDPLATFORM
ARG TARGETPLATFORM
ARG TARGETARCH

ARG BINARYEN_VERSION="version_105"

RUN echo "Running on $BUILDPLATFORM, building for $TARGETPLATFORM"

# AMD64
FROM targetarch as builder-amd64
ARG ARCH="x86_64"

# ARM64
FROM targetarch as builder-arm64
ARG ARCH="aarch64"

# GENERIC
FROM builder-${TARGETARCH} as builder

# Download binaryen sources
ADD https://github.com/WebAssembly/binaryen/archive/refs/tags/$BINARYEN_VERSION.tar.gz /tmp/binaryen.tar.gz

# Extract and compile wasm-opt
# Adapted from https://github.com/WebAssembly/binaryen/blob/main/.github/workflows/build_release.yml
RUN apk update && apk add build-base cmake git python3 clang ninja
RUN tar -xf /tmp/binaryen.tar.gz
RUN cd binaryen-version_*/ && cmake . -G Ninja -DCMAKE_CXX_FLAGS="-static" -DCMAKE_C_FLAGS="-static" -DCMAKE_BUILD_TYPE=Release -DBUILD_STATIC_LIB=ON && ninja wasm-opt

# Run tests
RUN cd binaryen-version_*/ && ninja wasm-as wasm-dis
RUN cd binaryen-version_*/ && python3 check.py wasm-opt

# Install wasm-opt
RUN strip binaryen-version_*/bin/wasm-opt
RUN mv binaryen-version_*/bin/wasm-opt /usr/local/bin

# Check cargo version
RUN cargo --version

# Check wasm-opt version
RUN wasm-opt --version

# Download sccache and verify checksum
ADD https://github.com/mozilla/sccache/releases/download/v0.2.15/sccache-v0.2.15-$ARCH-unknown-linux-musl.tar.gz /tmp/sccache.tar.gz
RUN sha256sum /tmp/sccache.tar.gz | egrep '(e5d03a9aa3b9fac7e490391bbe22d4f42c840d31ef9eaf127a03101930cbb7ca|90d91d21a767e3f558196dbd52395f6475c08de5c4951a4c8049575fa6894489)'

# Extract and install sccache
RUN tar -xf /tmp/sccache.tar.gz
RUN mv sccache-v*/sccache /usr/local/bin/sccache
RUN chmod +x /usr/local/bin/sccache

# Check sccache version
RUN sccache --version

# Add scripts
ADD optimize.sh /usr/local/bin/optimize.sh
RUN chmod +x /usr/local/bin/optimize.sh

ADD optimize_workspace.sh /usr/local/bin/
RUN chmod +x /usr/local/bin/optimize_workspace.sh

# Being required for gcc linking of build_workspace
RUN apk add --no-cache musl-dev

ADD build_workspace build_workspace
RUN cd build_workspace && \
  echo "Installed targets:" && (rustup target list | grep installed) && \
  export DEFAULT_TARGET="$(rustc -vV | grep 'host:' | cut -d' ' -f2)" && echo "Default target: $DEFAULT_TARGET" && \
  # Those RUSTFLAGS reduce binary size from 4MB to 600 KB
  RUSTFLAGS='-C link-arg=-s' cargo build --release && \
  ls -lh target/release/build_workspace && \
  (ldd target/release/build_workspace || true) && \
  mv target/release/build_workspace /usr/local/bin

#
# base-optimizer
#
FROM rust:1.60.0-alpine as base-optimizer

# Being required for gcc linking
RUN apk update && \
  apk add --no-cache musl-dev

# Setup Rust with Wasm support
RUN rustup target add wasm32-unknown-unknown

# Add wasm-opt
COPY --from=builder /usr/local/bin/wasm-opt /usr/local/bin

#
# rust-optimizer
#
FROM base-optimizer as rust-optimizer

# Use sccache. Users can override this variable to disable caching.
COPY --from=builder /usr/local/bin/sccache /usr/local/bin
ENV RUSTC_WRAPPER=sccache

# Assume we mount the source code in /code
WORKDIR /code

# Add script as entry point
COPY --from=builder /usr/local/bin/optimize.sh /usr/local/bin

ENTRYPOINT ["optimize.sh"]
# Default argument when none is provided
CMD ["."]

#
# workspace-optimizer
#
FROM base-optimizer as workspace-optimizer

# Assume we mount the source code in /code
WORKDIR /code

# Add script as entry point
COPY --from=builder /usr/local/bin/optimize_workspace.sh /usr/local/bin
COPY --from=builder /usr/local/bin/build_workspace /usr/local/bin

ENTRYPOINT ["optimize_workspace.sh"]
# Default argument when none is provided
CMD ["."]

根据这个文档，只有最后一个ENTRYPOINT才有效。但这 2 个位于 2 个不同的基础 docker 镜像中，因此在任何特殊情况下，这 2 个 ENTRYPOINT 会有效还是这只是一个错误？

Answer 1

您可以继续替换文件中的入口点，但是，这是一个多阶段 docker 文件。因此，如果您构建一个给定的阶段，那么您将获得不同的入口点。

例如：

docker build --target rust-optimizer .

将构建并包括运行时将运行的阶段optimize.sh .

然而

docker build .

当运行时会运行optimize_workspace.sh .