lambda-zig: A Custom Runtime for AWS Lambda

This is a sample custom runtime built in zig (0.12). Simple projects will execute in <1ms, with a cold start init time of approximately 11ms.

Some custom build steps have been added to build.zig, which will only currently appear if compiling from a linux operating system:

• zig build iam: Deploy and record a default IAM role for the lambda function
• zig build package: Package the lambda function for upload
• zig build deploy: Deploy the lambda function
• zig build remoterun: Run the lambda function

Custom options:

• function-name: set the name of the AWS Lambda function
• payload: Use this to set the payload of the function when run using zig build remoterun

Additionally, a custom IAM role can be used for the function by appending -- --role myawesomerole to the zig build deploy command. This has not really been tested. The role name is cached in zig-out/bin/iam_role_name, so you can also just set that to the full arn of your iam role if you'd like.

The AWS Lambda function is compiled as a linux ARM64 executable. Since the build.zig calls out to the shell for AWS operations, you will need the AWS CLI. v2.2.43 has been tested.

Caveats:

• Unhandled invocation errors seem to be causing timeouts
• zig build options only appear if compiling using linux, although it should be trivial to make it work on other Unix-like operating systems (e.g. macos, freebsd). In fact, it will likely work with just a change to the operating system check
• There are a ton of TODO's in this code. Current state is more of a proof of concept. PRs are welcome!

A sample project using this runtime can be found at https://git.lerch.org/lobo/lambda-zig-sample

Using the zig package manager

The zig package manager works just fine in build.zig, which works well for use of this runtime.

To add lambda package/deployment steps to another project:

1. zig build init-exe
2. Add a build.zig.zon similar to the below
3. Add a line to build.zig to add necessary build options, etc. Not the build function return type should be changed from void to !void

build.zig:

try @import("lambda-zig").lambdaBuildOptions(b, exe);

build.zig.zon:

.{
    .name = "lambda-zig",
    .version = "0.1.0",
    .dependencies = .{
        .@"lambda-zig" = .{
            .url = "https://git.lerch.org/lobo/lambda-zig/archive/fa13a08c4d91034a9b19d85f8c4c0af4cedaa67e.tar.gz",
            .hash = "122037c357f834ffddf7b3a514f55edd5a4d7a3cde138a4021b6ac51be8fd2926000",
        },
    },
}

That's it! Now you should have the 4 custom build steps