LambdaLift

LambdaLift is a utility designed to streamline the process of updating code for AWS Lambda functions.

It automates the entire deployment workflow: creating the zip archive, uploading the new version to S3, publishing a new Lambda version, and updating the function configuration.

LambdaLift also supports Lambda Layers and version pruning to keep your environment clean.

Motivation

When managing infrastructure as code (IaC) with tools like OpenTofu or Terraform, it is a best practice to separate infrastructure definitions from application code. This often means keeping them in separate repositories or lifecycles.

A common pattern is to:

1. Define the Lambda infrastructure (memory, IAM roles, networking) in the IaC repository, deploying a placeholder "Hello World" function.
2. Configure the IaC to ignore changes to the function code (lifecycle { ignore_changes = [source_code_hash] }).
3. Manage the actual application logic in a separate repository with its own CI/CD pipeline.

While this decouples infrastructure from business logic, manually publishing new function versions can be tedious.

LambdaLift bridges this gap. It handles the specific AWS operations required to effectively and safely deploy a new version of your Lambda function code without re-running your entire infrastructure pipeline.

Installation

Install the package as a development dependency using your preferred package manager:

Node.js / JavaScript / TypeScript

# Using npm
npm install --save-dev lambda-lift

# Using pnpm
pnpm add -D lambda-lift

# Using yarn
yarn add -D lambda-lift

Python

pip install lambda-lift

The Python package will automatically use npx if Node.js is available, or download a standalone binary otherwise.

Go

go install github.com/marnautoupages/lambda-lift@latest

The Go wrapper will automatically use npx if Node.js is available, or download a standalone binary otherwise.

Standalone Binary

Download pre-built binaries for Linux, macOS, or Windows from the GitHub Releases page.

Usage

Run the deploy command to start the deployment process:

npx lambda-lift deploy [options] [variables]

Options

Environment Variables / Interpolation

You can pass user-defined variables to the command line to interpolate values in your configuration. This is useful for deploying to different environments (e.g., dev, staging, prod).

# Pass variables directly as arguments
npx lambda-lift deploy ENV=dev REGION=us-east-1

Alternatively, you can use environment variables prefixed with LAMBDA_LIFT_:

LAMBDA_LIFT_ENV=dev npx lambda-lift deploy

Configuration

LambdaLift supports configuration via JSON, YAML, or JavaScript files (using cosmiconfig). It looks for files like package.json (under a lambdalift key), .lambdarc, lambdalift.config.js, etc.

Example lambdalift.config.json:

{
  "name": "my-app-${ENV}-function",
  "region": "us-east-1",
  "s3": {
    "bucket": "my-app-${ENV}-deployments",
    "key": "lambdas/my-function/"
  },
  "prune": 5,
  "artifacts": ["dist/**", "!dist/**/*.map"],
  "layer": {
    "nodejs": ["node_modules/**", "package.json"]
  }
}

Configuration Reference

Artifacts & Layers

The artifacts and layers properties invoke the zipper to package your code. They support flexible definitions:

1. Pre-built Zip: A string path ending in .zip. LambdaLift will upload this file directly.

   "artifacts": "./dist/function.zip"

2. Globs: A glob string or an array of glob strings. Matching files are added to the root of the archive.

   "artifacts": ["src/**/*.js", "package.json"]

3. Mapped Globs: An object where keys are the destination paths inside the zip, and values are globs.

   "artifacts": {
     ".": ["index.js"],
     "lib/": ["src/lib/**"]
   }

Interpolation Syntax

Use the syntax ${VAR_NAME} in your configuration strings to inject values dynamically.

For example, if you configure "name": "service-${STAGE}":

1. Run npx lambda-lift deploy STAGE=prod.
2. LambdaLift resolves the name to service-prod.

If a variable is missing, the deployment will fail with an error to prevent misconfiguration.