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docker-crowbar Build Status Docker Status

A Rust Crowbar development environment in a very restrictive Lambda image.

Available on Docker Hub at naftulikay/crowbar.

Background

Using crowbar, it's possible to build Rust Lambda functions which simply act a a pseudo-Python native library. This enables use of Rust, as it's an otherwise unsupported language for Lambda.

For the full background story, please see the README here, which was the ancestor of this Docker image.

Goals

The goals of this image are to:

  1. Provide a build environment for Crowbar projects which is consistent with the runtime execution environment of Lambda Python 3.6 projects.
  2. Provide utilities to make building a Lambda package straightforward and easy.

Example

To build a project in the local directory:

docker run -it --rm -e USER_UID="$(id -u)" -e USER_GID="$(id -g)" \
    -v $PWD:/home/rust/project \
  'cd project && cargo build --release' \
  'cd project && create-deployment target/release/liblambda.so target/deploy'

This will ensure that user permissions are correct (see the "UID and GID Remapping" section below), will mount the current directory at /home/rust/project within the container, and then will build a release of the shared library, and then will bundle a zip file containing liblambda.so and all linked libraries.

The final zip file created at target/deploy/lambda.zip can be uploaded as is to Lambda and should contain everything necessary to execute at runtime.

Utilities

A few utilities are provided; please note that these utilities will not be present in the runtime environment. If you would like to use them at runtime, please bake them into your Lambda deployment zip.

Configuration and Infrastructure Management

Terraform can be easily installed using bin/tfenv. Simply call tfenv $TERRAFORM_VERSION to install the given version of Terraform to ~/.local/bin.

The latest stable Ansible is also installed.

UID and GID Remapping

On start of the container, the bin/id-remap script will remap the rust user's UID and GID to the values of the USER_UID and USER_GID values. This is useful for using the image in varying environments such as CircleCI, in which the UID is 1001 and the GID is 1002, rather than the usually expected 1000:1000.

Here's how to ensure your file ownership is correct at runtime:

docker run -it --rm -e USER_UID="$(id -u)" -e USER_GID="$(id -g)"

Create Deployments

There is also a utility for creating ZIP deployments ready for Lambda from Crowbar: bin/create-deployment. This Python utility will find all dependent libraries (recursively) of liblambda.so and include them in the ZIP deployment archive.

The output archive will look somewhat like this:

.
├── lib
│   ├── libpthread.so
│   ├── libselinux.so
│   └── libz.so
└── liblambda.so

Lambda's LD_LIBRARY_PATH is set to the normal system default, with . and ./lib appended to the end. For anything not found in /usr/lib64 and /usr/local/lib64, the linker will thus attempt to load the libraries from . and then from ./lib/.

License

Licensed at your discretion under either: