Cargo Lambda New ​

The new command creates new Rust packages with a basic skeleton to help you start writing AWS Lambda functions with Rust. This command will create this package in a new sub-directory inside the directory where it's invoked. Run cargo lambda new PACKAGE-NAME to generate your new package.

This command uses templates packed as zip files, or from local directories. The default template supports HTTP Lambda functions, as well as functions that receive events defined in the aws_lambda_events crate. You can provide your own template using the --template flag.

The files Cargo.toml, README.md, and src/main.rs in the template are parsed with Liquid to dynamically render different files based on a series of global variables. You can see all the variables in the source code.

After creating a new package, you can use the build command to compile the source code.

Extensions ​

You can also use this subcommand to create new Lambda Extension projects. Use the flag --extension to create the right project:

cargo lambda new --extension extension-project

cargo lambda new --extension extension-project

Logs extensions ​

If you want to build a Lambda Logs extension, add the --logs to the previous command. Cargo Lambda will create the scaffolding for a Logs extension:

cargo lambda new --extension --logs logs-project

cargo lambda new --extension --logs logs-project

Templates ​

Cargo Lambda uses template repositories as scaffolding for new projects. You can see the default template for functions and the default template for extensions in GitHub.

Cargo Lambda can also download custom templates from other GitHub repositories by using the --template with the repository url, for example:

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    new-project

The --template flag also accepts routes to specific repository branches and tags:

cargo lambda new \
    --template https://github.com/calavera/custom-template/branch/stable \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template/branch/stable \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template/tag/v0.1.0 \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template/tag/v0.1.0 \
    new-project

Template rendering ​

Cargo Lambda uses Liquid to render files from a given template.

By default, only a few files in a template are rendered by Liquid, the rest are copied into the new project's directory as they are. These are the files rendered by Liquid by default:

• README.md
• Cargo.toml
• src/main.rs
• src/lib.rs
• src/bin/*.rs

If you want to render additional files you can use the flag --render-file with a path relative to the root of the directory where the project is created:

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --render-file package.json \
    --render-file lib/cdk-stack.ts \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --render-file package.json \
    --render-file lib/cdk-stack.ts \
    new-project

Template variables ​

When you create a new project, Cargo Lambda adds several variables to the template engine that you can use in any file that's rendered by Liquid.

These are the variables for function templates:

• project_name: The name of the project and package.
• bin_name: The name of the main binary to compile if it's different than the project name.
• http_function: Whether the function is an http function.
• http_feature: the lambda event feature type that integrates with an http function.
• event_type: the Rust event type that the function receives.
• event_type_feature: the lambda event feature name in the aws_lambda_events crate.
• event_type_import: The Rust import statement that the function uses.

These are the variables for extension templates:

• project_name: The name of the project and package.
• bin_name: The name of the main binary to compile if it's different than the project name.
• logs: Whether the extension is a Logs extension or not.

You can add additional variables to render by a template with the flag --render-var. This flag takes variables in the format KEY=VALUE:

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --render-var CDK_VERSION=2 \
    --render-var CDK_STACK=lambda-stack.ts \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --render-var CDK_VERSION=2 \
    --render-var CDK_STACK=lambda-stack.ts \
    new-project

Ignore files ​

By default, Cargo Lambda will ignore the .git directory and the LICENSE file in the template repository. If you want to ignore additional files in a new project, you can use the flag --ignore-file:

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --ignore-file package-lock.json \
    --ignore-file yarn-lock.json \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --ignore-file package-lock.json \
    --ignore-file yarn-lock.json \
    new-project

Interactive options ​

Cargo Lambda's new subcommand displays several interactive questions for the default templates to work. If you have a custom template and you want to skip these questions, you can use the flag --no-interactive:

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --no-interactive \
    new-project

cargo lambda new \
    --template https://github.com/calavera/custom-template \
    --no-interactive \
    new-project