import AWS lambda layer for pymysql

Question

I need to deploy a lambda function carrying out a process with the python package pymysql, my python version is 3.6 and for this purpose I will use the lambda layers to avoid bring my whole code. In order to achieve this I have follow the steps below:

• create in my local machine a python virtualenv
• install the pakcage pymysql

• create a separate folder where I move the pymysql package installed in my virtual env cp -r /myvirtualenv/lib/python3.6/site-packages/pymysql ~/home/user/packagelambda/

• within the path ~/home/user/packagelambda/ compress this package into a zip file to be uploaded as AWS lambda layer zip -r rdsconnection.zip *

• upload this zipfile as new layer into aws lambda dashboard

Once I complete the process above , I went to my code and create two scripts to modularize my execution , a first script called md_conenction.py as below:

import json
import boto3
import pymysql 
import csv
from datetime import datetime


def json_param():
    s3 = boto3.resource('s3')
    bucketname= "bucket"
    file= "file.json"
    object= s3.Object(bucketname,file)
    body = object.get()['Body'].read().decode('utf8')

    param= json.loads(body)

    return param["host"], param["user"], param["password"], param["database"]

def db_connection():

    host,user,password,database = json_param()

    dbconnection = pymysql.connect(host,user,password,database)
    dbcursor = dbconnection.cursor()

    return dbconnection, dbcursor

Additionally a secon script in lambda functions by default called lambda_function.py with the content below:

import json
from md_connection import db_connection

def lambda_handler(event, context):

    dbconnection, dbcursor = db_connection()
    print(dbcursor)


    return {
        'statusCode': 200,
        'body': json.dumps('Hello from Lambda!')
    }

Finally I when to my layers option on the designer and appends the new layer built previously. Once complete this process I still keep on getting the error Unable to import module 'lambda_function': No module named 'pymysql' after every execution.

I would like to highlight that I have tried to carry out the process building a layer in two ways:

1. just including the package downloaded by python pymysql
2. including two folders after the package installation pymysql and PyMySQL-0.9.3.dist-info
3. I include runtime compability for Python 3.6 and up to python 3.8 upon layer building

Answer 1

Create a directory python copy pymysql and its dependency into the directory. Zip the python directory and upload it to the layer. The folder structure inside the zip matters. The root directory should be python