Is it possible to add paths to the PATH environment variable through serverless.yml?

Question

When I create an AWS Lambda Layer, all the contents / modules of my zip file go to /opt/ when the AWS Lambda executes. This easily becomes cumbersome and frustrating because I have to use absolute imports on all my lambdas. Example:

import json
import os
import importlib.util
spec = importlib.util.spec_from_file_location("dynamodb_layer.customer", "/opt/dynamodb_layer/customer.py")
module = importlib.util.module_from_spec(spec)
spec.loader.exec_module(module)

def fetch(event, context):

    CustomerManager = module.CustomerManager
    customer_manager = CustomerManager()

    body = customer_manager.list_customers(event["queryStringParameters"]["acquirer"])

    response = {
        "statusCode": 200,
        "headers": {
            "Access-Control-Allow-Origin": "*"
        },
        "body": json.dumps(body)
    }

    return response

So I was wondering, is it possible to add these /opt/paths to the PATH environment variable by beforehand through serverless.yml? In that way, I could just from dynamodb_layer.customer import CustomerManager, instead of that freakish ugliness.

Answer 1

I've Lambda layer for Python3.6 runtime. My my_package.zip structure is:

my_package.zip
 - python
   - lib
     - python3.6
       - site-packages
         - customer

All dependencies are in build folder in project root: e.g. build/python/lib/python3.6/site-packages/customer

Relevant section of my serverless.yml

layers:
  my_package:
    path: build             
    compatibleRuntimes:     
      - python3.6

In my Lambda I import my package like I would do any other package: import customer