Example AWS Lambda function using the AWS C++ Lambda runtime

Shows how to build and package an AWS Lambda function using the AWS C++ Lambda runtime. This function can replace the Python Lambda function used in the Get started with functions scenario sample code.

Creating the Lamba function package

The Lambda function is built and packaged using Docker.

Prerequisites

Docker is needed to build and package the Lambda function. The Docker website contains installation instructions.

Build and run the docker image

This sample code contains a DockerFile which is used to build the Docker image. Using a shell application, navigate to the folder containing this README. Then enter the following command:

bashcd

docker build . -f Dockerfile -t cpp_lambda_image

Now run the Docker image as a container using the following command:

bash

docker run -i -t --name cpp_lambda --mount type=bind,source="$(pwd)",target=/cpp_lambda cpp_lambda_image bash

Your command line should now be running from within the Docker container. The preceding run command should have bound the directory containing this README to the Docker container.

Test whether the host directory is correctly bound by entering the following command:

bash

ls /cpp_lambda

You should see the contents of this README's directory.

bash

Dockerfile         README.md          calculator         increment

Build and package the Lambda function

Now build the two Lambda functions used by the sample code. Because the Docker container is bound to the directory containing this README, the source code can be accessed within the container at /cpp_lambda.

Note: The AWS Lambda C++ Runtime is required for the next steps. It was installed when the Docker image was built.

Build the "Increment" Lambda function code.

bash

cd /cpp_lambda/increment && \
mkdir build && \
cd build && \
cmake3 .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=~/install && \
make && \
make aws-lambda-package-cpp_lambda_increment

Build the "Calculator" Lambda function code.

bash

cd /cpp_lambda/calculator && \
mkdir build && \
cd build && \
cmake3 .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=~/install && \
make && \
make aws-lambda-package-cpp_lambda_calculator

These build steps have generated two zip files which will be used by the sample code in Get started with functions.

These files are referenced in the following section of code:

cpp

#if USE_CPP_LAMBDA_FUNCTION
        static Aws::String LAMBDA_HANDLER_NAME(
                "cpp_lambda_calculator");
        static Aws::String INCREMENT_LAMBDA_CODE(
                SOURCE_DIR "cpp_lambda/increment/build/cpp_lambda_increment.zip");
        static Aws::String CALCULATOR_LAMBDA_CODE(
                SOURCE_DIR "cpp_lambda/calculator/build/cpp_lambda_calculator.zip");
#else

Finally, in the source file get_started_with_functions_scenario.cpp, set the preprocessor constant USE_CPP_LAMBDA_FUNCTION to 1.

cpp

#define USE_CPP_LAMBDA_FUNCTION 1