git-lambda-layer | A layer for AWS Lambda that allows your functions | Function As A Service library

There are a few problems.

First, you need to wait for the git process to exit. To do this with subprocess.Popen, call .wait() on the returned Popen object. However, I'd recommend using subprocess.check_call() instead to automatically wait for the process to exit and to raise an error if the process returns a non-zero exit status.

Second, there's no need to specify shell=True since you're not using any shell expansions or built-ins. In fact, when passing an argument list when using shell=True, the first item is the command string, and the remaining items are arguments to the shell itself, not the command.

Lastly, you're missing a slash in your GitHub URL.

Try this instead: