AWS Lambda Function With RDS MySQL

How To Use AWS Lambda Function With AWS RDS MySQL

If you ever want to have small service that access database and returns some result then you should go for AWS Lambda as it costs you only when it gets invoked. So You will be paying less then an ec2 instance.

Let's go ahead and see how we can create a lambda function which will interact with a database build on AWS RDS MySQL. You can choose your own database like postgresql hosted on an ec2 instance, but here for the sake of simplicity we will be using RDS MySQL.

First get your database Instance Up and running. You will need to have its endpoint, username, password and database name.

• Get the repository from my github.
• Create a database instance.
• Fill in the databases instance details in main.py
• Make sure you have correct security group settings in place.

Below is the main sample code (main.py):

# A lambda function to interact with AWS RDS MySQL

import pymysql
import sys

REGION = 'us-east-1'

rds_host  = "appychip.c7hugt6dv8dv.ap-south-1.rds.amazonaws.com"
name = "appychip"
password = "appychippassword"
db_name = "appychip"

def save_events(event):
    """
    This function fetches content from mysql RDS instance
    """
    result = []
    conn = pymysql.connect(rds_host, user=name, passwd=password, db=db_name, connect_timeout=5)
    with conn.cursor() as cur:
        cur.execute("""insert into test (id, name) values( %s, '%s')""" % (event['id'], event['name']))
        cur.execute("""select * from test""")
        conn.commit()
        cur.close()
        for row in cur:
            result.append(list(row))
        print "Data from RDS..."
        print result

def main(event, context):
    save_events(event)
        


# event = {
#   "id": 777,
#   "name": "appychip"
# }
# context = ""
# main(event, context)

The point here to note is that we are using pymysql library which we need to install in our current working directory where our main.py file is present. To install it you can run the following command:

pip install pymysql -t .

Now, since we have the required library in place, we need to create the zip of our code and upload it on the lambda function. To make a zip run the following command:

zip -r lambdaRDS.zip `ls`

Save the lambda function and go ahead running the script by passing a test event to the function which looks like below:

{
  "id": "1",
  "name": "appychip"
}

Now go ahead running the lambda function. On successful execution, this will insert a record into mysql.

Hurray!!! you just created a lambda function which interacts with database. To create an API endpoint to your lambda function, checkout our tutorial Scalable architecture using AWS API Gateway, lambda function and dynamodb.