Using Mysql2 gem in AWS Lambda for Ruby

3 min readJul 21, 2019

AWS added Ruby to the list of supported languages for AWS Lambda at the end of the year 2018. The official document does a good job of explaining how to get started with it. However, it doesn't cover how to include gems that have dependencies on native extensions, like mysql2.

The scope of the post is to demonstrate how to make mysql2 gem work with Lambda. And, it uses RDS to achieve this. It is assumed that the reader has prior experience with AWS services and the following topics will be excluded in the post.

Creating an RDS instance.
Configuring Lambda function to connect to RDS.

Before we start, keep in mind that the complete code can be found here.

Create a new folder and change the working directory to the same.

mkDir sample_ruby_lambda
cd sample_ruby_lambda

2. Install RVM, Ruby, and Bundler.

rvm install ruby-2.5.0
gem install bundler

3. Install Docker.

4. Create a Docker file(Dockerfile).

FROM lambci/lambda:build-ruby2.5RUN yum -y install mysql-devel
RUN gem update bundlerCMD "/bin/bash"

5. Create a Docker image.

docker build -t lambda-ruby2.5-sales-dashboard .

6. Create a ruby handler file(handler.rb)

require 'mysql2'def main(event:, context:)
  # client = Mysql2::Client.new(
  #   :host => "******.us-east-*.rds.amazonaws.com",
  #   :username => "********",
  #   :database=> "*******",
  #   :password=> "**********",
  #   :port => 3306)
  # results = client.query("SELECT COUNT(*) FROM employees;").to_a
  {
    test: Mysql2::VERSION
  }
end

7. Create a Gemfile(Gemfile)

source "https://rubygems.org"gem "mysql2"

8. Using RVM use the ruby-2.5.0(If not present instal it)

rvm use ruby-2.5.0

9. Execute the following command to get inside the container:

docker run --rm -it -v $PWD:/var/task -w /var/task lambda-ruby2.5-sales-dashboard

10. From inside the container, run;

bundle config --local build.mysql2 --with-mysql2-config=/usr/lib64/mysql/mysql_config
bundle config --local silence_root_warning true
bundle install --path vendor/bundle --clean
mkdir -p /var/task/lib
cp -a /usr/lib64/mysql/*.so.* /var/task/lib/

11. Smoke test: Run the following inside the container.

ruby -e "require 'handler'; puts main(event: nil, context: nil)"

12. You should get a response like this,

{ test: "0.5.2" }

13.Package to Zip.

rm -f deploy.zip
zip -q -r deploy.zip .

14. Exit the container bash and simulate the lambda instance.

docker run --rm -v "$PWD":/var/task lambci/lambda:ruby2.5 handler.main

You can expect the following result

START RequestId: 52fdfc07-2182-154f-163f-5f0f9a621d72 Version: $LATESTEND RequestId: 52fdfc07-2182-154f-163f-5f0f9a621d72REPORT RequestId: 52fdfc07-2182-154f-163f-5f0f9a621d72 Duration: 7.85 ms Billed Duration: 100 ms Memory Size: 1536 MB Max Memory Used: 21 MB{"test":"0.5.2"}

15. Deploy to the AWS Lambda using the console, or command line

aws lambda create-function \— region us-east-1 \— function-name RubyLambdaMySql \— zip-file fileb://deploy.zip \— runtime ruby2.5 \— role arn:aws:iam::************:role/service-role/lambdabasicfunc \— timeout 20 \— handler handler.main

16. Go to AWS lambda console and test the code.

Using Mysql2 gem in AWS Lambda for Ruby

Written by deekshith h