Problems using MySQL with AWS Lambda in Python

Just update your lambda layer by uploading two packages: - sqlalchemy - PyMySQL (driver to use instead of mysqlclient)

Now update your driver url to "mysql+pymysql://...".

This makes you use pymysql driver which is compatible with Lambda environment for your existing environments.

Don't forget to set VPC endpoint for RDS. This keeps performance and security in check.

TLDR: Yes, you CAN use mysqlclient in AWS Lambda Python functions.

Here's one way - by creating your own AWS Lambda Layer for mysqlclient (i.e. MySQLdb).

Then I get Unable to import module 'lambda_function': No module named MySQLdb

I know that if I work on a Linux box, then it should work fine (as suggested by some people), but I am wondering if I can make it work from an OS X box.

I too was facing the exact same error while trying to import MySQLdb in my AWS Lambda Python function.

After a lot of searching for a solution and not happy with using pymysql as a substitute (for performance and compatibility reasons), I ended up building my own AWS Lambda Layer for mysqlclient. I could not find a "ready-made" layer for mysqlclient - not even at the awesome KLayers project. I am glad to share a GitHub repo with an example "ready-made" layer and an easy solution to build your own custom layer for your requirements that uses the recommended procedure by AWS.

mysqlclient (MySQLdb) is a Python wrapper around a high-performance C implementation of the MySQL API. This makes it typically much faster than pure-python implementations such as pymysql in most cases (see this list for some examples), but it also brings some problems such as the one you are facing.

Since it is compiled against the mysql-devel package (e.g. a .rpm or .deb file provided by MySQL), mysqlclient is linked to a platform-specific binary such as libmysqlclient.so in order to work. In other words, the libmysqlclient.so from a Mac OS laptop (as an example) won't work in the AWS Lambda environment which uses some form of Amazon Linux 2 as of this writing. You need a libmysqlclient.so compiled in and for the AWS Lambda environment (or as close to it as possible) for it to work in your AWS Lambda function.

A closely-simulated AWS-Lambda environment is available in the form of Docker images from lambci.

So to package an AWS-Lambda compatible mysqlclient you could:

• pull a suitable docker container such as lambci/lambda:build-python3.8
• import the MySQL repo GPG key
• install the MySQL repo setup RPM so that yum can find and download other MySQL repo packages
• yum install the necessary dependencies such as the appropriate mysql-devel rpm for your use-case
• run pip install mysqlclient in the container
• zip the necessary libmysqlclient.so file and mysqlclient's python lib directories

This is more-or-less the officially-recommended procedure by AWS: see How do I create a Lambda layer using a simulated Lambda environment with Docker? .

The zip thus created can be used to create a new AWS Lambda layer for mysqlclient. You can use this layer to readily use mysqlclient without any errors in your Lambda function.

After a lot of hair-pulling, I finally got the full procedure to work and automated it into a single script (build.sh) in this GitHub project. The code builds a layer.zip file that you can directly upload as a new AWS Lambda layer. The project currently builds for Python3.8 and MySQL server 8.0.x, but can be easily adapted to a different Python version and target MySQL version using the instructions and tools provided. There is also a ready-to-use layer.zip in the repo - in case you want to use mysqlclient against MySQL v8.0.x and in Python 3.8 (both tested) in your AWS Lambda function. Our production env uses SqlAlchemy which uses this MySqlClient Lambda layer and it's been working great for us.

After you configure your Lambda function to use a layer built as described (e.g. using the tools in the aforementioned repo), you can just import MySQLdb as usual in your Lambda function and get on with writing your real code:

import MySQLdb

def lambda_handler(event, context):
    return {
        'statusCode': 200,
        'body': 'MySQLdb was successfully imported'
    }

Hope this helps.

AWS recently came out with a great solution for the issue of database drivers and database access in Lambda: the Aurora Data API. The Data API tunnels SQL over HTTP using AWS standard auth. This bypasses the problems with compiling native code and using traditional database connection models in Lambda.

I ended up writing a DB-API compatible driver for it: aurora-data-api (and a SQLAlchemy dialect using it):

import aurora_data_api

cluster_arn = "arn:aws:rds:us-east-1:123456789012:cluster:my-aurora-serverless-cluster"
secret_arn = "arn:aws:secretsmanager:us-east-1:123456789012:secret:MY_DB_CREDENTIALS"
with aurora_data_api.connect(aurora_cluster_arn=cluster_arn, secret_arn=secret_arn, database="my_db") as conn:
    with conn.cursor() as cursor:
        cursor.execute("select * from pg_catalog.pg_tables")
        print(cursor.fetchall())

For a use case like Lambda you'll be a lot happier using a pure python implementation like PyMySQL.

It's a drop in replacement for MySQLdb that follows the Python Database API specification. For most things like triggered Lambda events it will be just as fast.

I've used it in production a lot and it works great.