[aws-lambda] Lambda zip from DockerFile

[nakedible]

Currently CDK supports many ways to generate Lambda assets:

• Lambda zip can be provided directly
• Lambda zip can be created automatically from a directory or set of files
• NodeJS functions can be bundled automatically by Parcel to create a zip
• Custom bundler docker images can be provided

However, I think there is one obvious way that is missing: generating the Lambda zip by building a DockerFile. The code should simply build a Dockerfile, and then extract the /var/task directory from the built image and zip it for Lambda.

This would allow all the features of a Dockerfile to be used in a really simple manner - such as multi-stage builds, caching, etc.

Use Case

Building Lambda functions that utilize native code requires using Docker images to get the right libraries. It is hard to build a custom bundler for each usage when the desire is to simply be able to customize the build process inside the docker.

Proposed Solution

The calling code could be:

lambda.Code.fromDocker(path.join(__dirname, 'my-docker-lambda'))

Should have support for common Docker build things like build arguments, specifying the Dockerfile separately from the root directory, etc.

Simple example for Nodejs:

FROM amazon/aws-sam-cli-build-image-nodejs12.x
COPY package.json package-lock.json /var/task/
RUN npm ci
COPY . /var/task/

Simple example for Python:

FROM amazon/aws-sam-cli-build-image-python38
COPY requirements.txt /var/task/
RUN pip install -y -r requirements.txt
COPY . /var/task/

More complex example for Rust:

FROM amazon/aws-sam-cli-build-image-provided

RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \
 | sh -s -- -y --profile minimal --default-toolchain stable
RUN /root/.cargo/bin/rustup target add x86_64-unknown-linux-musl

WORKDIR /code
COPY Cargo.toml Cargo.lock ./

RUN set -x\
 && mkdir -p src\
 && echo "fn main() {println!(\"broken\")}" > src/main.rs\
 && /root/.cargo/bin/cargo build --release

COPY src/ src/
RUN set -x\
 && find target/release -type f -name code -exec touch -t 200001010000 {} +\
 && /root/.cargo/bin/cargo build --release

RUN cp /code/target/release/bootstrap /var/task/

Other

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

---

This is a 🚀 Feature Request

[github-actions]

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