How to build a Python project for a specific version of Python

Question

I have an app that I would like to deploy to AWS Lambda and for this reason it has to have Python 3.9.

I have the following in the pyproject.toml:

name = "app"
readme = "README.md"
requires-python = "<=3.9"
version = "0.5.4"

If I try to pip install all the dependencies I get the following error:

ERROR: Package 'app' requires a different Python: 3.11.1 not in '<=3.9'

Is there a way to specify the Python version for this module?

I see there is a lot of confusion about this. I simply want to specify 3.9 "globally" for my build. So when I build the layer for the lambda with the following command it runs:

pip install . -t pyhon/

Right now it has only Python 3.11 packaged. For example:

❯ ls -larth python/ | grep sip
siphash24.cpython-311-darwin.so

When I try to use the layer created this way it fails to load the required library.

Answer 1

To build a Python project for a specific version of Python, you can take the following steps:

1. Make sure that the specific version of Python is installed on your machine.

2. Specify the version of Python that your project requires in your project's configuration file (in your case, pyproject.toml) using the python_requires field. For example

1. python_requires = >=3.9

2. Create a virtual environment with the specific version of Python installed:

   python3.9 -m venv myenv

3. Activate the virtual environment:

   source myenv/bin/activate

4. Install your project's dependencies in the virtual environment:

   pip install .

5. When building the layer for AWS Lambda, make sure to use the virtual environment you created in step 3. For example:

   pip install . -t python/ --no-compile

   The --no-compile option is recommended for AWS Lambda to avoid potential issues with binary compatibility between different versions of Python.

6. Package the contents of the virtual environment (including your project's dependencies) and upload it to AWS Lambda as a layer.

7. When configuring your AWS Lambda function, specify the layer you created in step 7 as a runtime dependency.

By following these steps, you should be able to build and deploy your Python project for the specific version of Python required by AWS Lambda.

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