Generate AWS lambda zips using `uv build`

[kishaningithub]

Generating python lambda zips is a cumbersome process. It would be great if uv build can have the ability to generate AWS Lambda zip files which can be used to create lambda function in AWS.

AWS Documentation Link: https://docs.aws.amazon.com/lambda/latest/dg/python-package.html#python-package-create-dependencies

[samypr100]

Could you expand on how are you currently using uv to generate these?

[kishaningithub]

My shell script does the following

• Use uv to build wheel file

• Extract the wheel file

• Copy contents of the wheel into a directory

• Copy Install project runtime dependencies into the same directory using pip install --target

• Zip the directory

• Upload the zip to AWS

[samypr100]

Is there a reason you wouldn't be able to use --target like the AWS lambda guide says? I'm trying to understand if there's a compatibility gap with what pip enables you to do.

[kishaningithub]

The 4th point of copying runtime dependencies is exactly a pip install --target. I guess "installing" would have been a better word than "copying".. will update the above

[zanieb]

At the very least it'd be nice to include some documentation for this process.

I'm not sure how we'd expose this if we did. An alternative uv build output format?

[doron98]

What is tricky is including path dependencies anomalyco/sst#5132

[kishaningithub]

@zanieb In my mind it was an alternative uv build output format

[williamrjribeiro]

Hi @kishaningithub , I'm struggling with this issue as well. Can you share your shell script please?

[kishaningithub]

@williamrjribeiro The script i am using is basically the same as the in the AWS documentation. Can you let know the issue you are facing?

[toddlers]

here is something worked out for me @williamrjribeiro , I didn't try to use pip, because that's what I am running away from.

#!/usr/bin/env bash

# Exit immediately if a command exits with a non-zero status
set -e

# Step 1: Clean up old builds
echo "Cleaning up old builds..."
rm -rf build dist lambda_package lambda_function.zip

# Step 2: Verify the virtual environment exists
if [ ! -d ".venv" ]; then
    echo "Error: Virtual environment '.venv' not found!"
    exit 1
fi

# Step 4: Build the wheel file using `uv`
echo "Building the wheel package..."
uv build --wheel


# Step 3: Use `uv run` to determine the Python version
echo "Detecting Python version..."
PYTHON_VERSION=$(echo "import sys; print(f'{sys.version_info.major}.{sys.version_info.minor}')"|uv run -)
if [ -z "$PYTHON_VERSION" ]; then
    echo "Error: Could not determine Python version!"
    exit 1
fi
echo "Detected Python version: $PYTHON_VERSION"


# Step 4: Locate site-packages directory
VENV_SITE_PACKAGES=".venv/lib/python$PYTHON_VERSION/site-packages"
if [ ! -d "$VENV_SITE_PACKAGES" ]; then
    echo "Error: Could not locate site-packages in the virtual environment at $VENV_SITE_PACKAGES!"
    exit 1
fi


# Step 5: Extract the wheel file
echo "Extracting the wheel file..."
WHEEL_FILE=$(ls dist/*.whl | head -n 1)  # Get the first wheel file
if [ -z "$WHEEL_FILE" ]; then
    echo "Error: No wheel file found in 'dist/' directory!"
    exit 1
fi
mkdir -p lambda_package
unzip -q "$WHEEL_FILE" -d lambda_package

# Step 6: Copy dependencies from the virtual environment
echo "Copying dependencies from virtual environment..."
cp -r "$VENV_SITE_PACKAGES/"* lambda_package/

# Step 7: Package the Lambda deployment
echo "Packaging Lambda deployment..."
cd lambda_package

# here using -u option helped me and it speed up the zip creation too
# Replace (update) an existing entry in the zip archive only if it has been 
# modified more recently than the version already in the zip archive

zip -qr ../lambda_function.zip .
cd ..

echo "Lambda deployment package created successfully: lambda_function.zip"

# Step 8: Upload to AWS Lambda
LAMBDA_FUNCTION_NAME="delete_me"  # Replace with your Lambda function name
echo "Uploading to AWS Lambda: $LAMBDA_FUNCTION_NAME"
aws lambda update-function-code --function-name "$LAMBDA_FUNCTION_NAME" --zip-file fileb://lambda_function.zip

echo "Deployment complete!"

[williamrjribeiro]

@toddlers Thank you for the script! 🙏

I'm using SST+Pulumi to deploy my little Python script to a lambda function. The lambda fails when it runs with error [ERROR] Runtime.ImportModuleError: Unable to import module 'main': No module named 'main' Traceback (most recent call last):

Here's my pyporject.toml:

[project]
name = "poc-events_python-consumer"
version = "0.0.0"

dependencies = [
    "sst",
    "pydantic>=2.10.2",
    "cloudevents[pydantic]",
]

requires-python = "~=3.12"

[tool.uv.pip]
no-strip-extras = true

[tool.uv.sources]
sst = { git = "https://github.com/sst/sst.git", subdirectory = "sdk/python", branch = "dev" }
cloudevents = { git = "https://github.com/cloudevents/sdk-python.git", branch = "main" }

[tool.setuptools]
py-modules = []

[project.scripts]
handler = "lambda:handler"

The script path is python-consumer/src/lambda/__init__.py which has the def handler function.

This is how the lambda function is created with Pulumi:

const pythonConsumer = new aws.lambda.Function("PocEventPythonConsumer", {
      role: lambdaRole.arn,
      runtime: "python3.12",
      handler: "lambda.handler",
      code: $asset("packages/python-consumer/lambda_package/"),
    });

Maybe I should just wait for anomalyco/sst#5132 to be merged and released.

[kucharzyk-sebastian]

In case anyone is looking for a solution using Python, UV, and AWS CDK, it seems they're going to support it in #31238