AWS SAM Rust - Deploy multiple lambda functions from same crate - amazon-web-services

Question

I'm trying to deploy a basic serverless application that contains two Rust lambda functions. I'm using SAM to deploy the application.
The issue is how to get SAM to pick up the correct "bootstrap" file. Because both functions are built in the same CodeUri path, SAM does not execute both the Make commands. Instead, it just copies the output of Function1 to Function2 (this seems like a design flaw in SAM?). Thus, both lambdas currently get deployed with the same code.
My build directory is
myapp/
- src/
- bin/
- function1.rs (note: function1 & 2 depend on lib.rs)
- function2.rs
- lib.rs
- Cargo.toml
- Makefile
- template.yaml
The template.yaml file:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Globals:
Function:
Handler: bootstrap.is.the.handler
Runtime: provided.al2
Architectures:
- x86_64
Resources:
Function1:
Type: AWS::Serverless::Function
Properties:
CodeUri: .
Function2:
Type: AWS::Serverless::Function
Properties:
CodeUri: .
The Makefile is:
build-Function1:
cargo lambda build
cp ./target/lambda/function1/bootstrap $(ARTIFACTS_DIR)
build-Function2: # This never gets run!
cargo lambda build
cp ./target/lambda/function2/bootstrap $(ARTIFACTS_DIR)
Commands to build/deploy
sam build
sam deploy
I'm open to other build structures. I've also tried structuring the project using rust workspaces. But, because SAM copies the build source to a separate directory, I cannot find a way to add module dependencies.

Answer 1

After much struggle, I have come up with a hacky solution, that I'm sure cannot be the recommended way.
Use rust workspaces, so the folder structure is:
root/
common/
lib.rs
Cargo.toml
function1/
main.rs
Cargo.toml
Makefile
function2/
main.rs
Cargo.toml
Makefile
Cargo.toml
template.yaml
root/Cargo.toml:
[workspace]
members = [
"common"
"function1",
"function2",
]
Set template.yaml file to use different codeURIs:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Globals:
Function:
Handler: bootstrap.is.the.handler
Runtime: provided.al2
Architectures:
- x86_64
Resources:
Function1:
Type: AWS::Serverless::Function
Properties:
CodeUri: function1
Function2:
Type: AWS::Serverless::Function
Properties:
CodeUri: function2
(The hack step) In each Makefile, cp back into the source dir so it builds with all the source. (This has added benefit of sharing the build cache between targets)
build-Function1:
cd $(PWD); cargo lambda build --release
cp $(PWD)/target/lambda/function1/bootstrap $(ARTIFACTS_DIR)
This solution is compatible with cargo lambda watch and sam build/sam deploy commands.
Binary size is large since all lambdas duplicate the base library. I'm uncertain if this is avoidable with Rust.
I'm yet to trial it with deployment from CI servers.