Salesforce Package Cloud Native Buildpack (CNB) in Rust

Dev

Pre-reqs

• Install rust - rustup
• Add musl target to rustup - rustup target add x86_64-unknown-linux-musl
• Install cargo-make: cargo install cargo-make
• On mac install homebrew-musl-cross: brew install FiloSottile/musl-cross/musl-cross

Test

Run unit tests:

$ cargo test

Pack build Example

cargo make pack --profile "production" \
&& pack build sf_package_app --path tests/fixtures/sf-package -B heroku/buildpacks:20 --buildpack ./target  -v \
&& docker run -it --entrypoint worker sf_package_app

$ pack inspect sf_package_app | grep -A10 Processes
Processes:
  TYPE                 SHELL        COMMAND              ARGS
  web (default)        bash         node index.js
  worker               bash         while true; do echo 'lol'; sleep 2; done

Structure

The code produces a single binary that contain both the "detect" and "build" interfaces:

fn main() {
    cnb_runtime(detect, build, GenericErrorHandler);
}

The function cnb_runtime changes behavior based on the name of the calling file. In the Makefile.toml the binary is symlinked with different names (detect versus build):

fs::hard_link(destination.join("bin/build"), destination.join("bin/detect")).unwrap();

The package can be complied for linux (musl) by running:

cargo make pack --profile "production"

This produces a target/bin/detect and target/bin/build that can be used for pack.

The functionality of those two binaries are come from the functions with the same name:

fn detect(context: GenericDetectContext) -> Result<DetectOutcome, E> {
  //...
}
fn build(context: GenericDetectContext) -> Result<(), E> {
  // ...
}