lambda-docker-prototype

Prototype of a project that uses AWS Lambda, Docker, SAM, Python. Inside of it you can found two functions. One of the functions is a simple "Hello World". The other one is a function that have a custom third-part image, that execute an random binary.

I don't know why this repo exists, I'm just playing with AWS Lambda to see its power.

Getting started

First time

Install AWS CLI

sudo apt install awscli

Install SAM following (this steps)[https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-install.html].

Configure AWS. Put your AWS User credentials.

aws configure

Configure your project and deploy it:

sam deploy --guided

Modify

You can open functions/your_function/app.py file and change the behavior of the functions. Each folder inside functions folder is like a sub project, with its own Dockerfile that describe its image.

Build

Just run:

sam build

This build your images base on the Dockerfile define in each function.

Test locally

If you want to test your HelloWorldFunction function:

sam build
sam local invoke HelloWorldFunction --event events/event.json

The SAM CLI can also emulate your application's API. Use the sam local start-api to run the API locally on port 3000.

sam local start-api
curl http://localhost:3000/hello

Deploy

Just run:

sam deploy --guided

Or, if you already have an samconfig.toml file, run:

sam deploy

Add a new function

In the functions directory, select hello_world and copy it next to it. Then open template.yaml file and copy the HelloWorldFunction bundle. Make your custom changes, modify the events section. Modify DockerContext, change ./functions/hello_world to the new location. You can also put some custom DockerTag. It'll be the name of the image of that function. You also have to add a repositoy to your samconfig.toml file. So, at your new deploy, run:

sam deploy --guided

Unit tests

Tests are defined in the tests folder in this project. Use PIP to install the pytest and run unit tests from your local machine.

pip install pytest pytest-mock --user
python -m pytest tests/ -v

Cleanup

To delete the sample application that you created, use the AWS CLI. Assuming you used your project name for the stack name, you can run the following:

aws cloudformation delete-stack --stack-name lambda-docker-prototype

Miscellaneous

Files and folders

This project contains source code and supporting files for a serverless application that you can deploy with the SAM CLI. It includes the following files and folders.

• functions - Code for the application's Lambda functions and Dockerfiles.
• events - Invocation events that you can use to invoke the function.
• tests - Unit tests for the application code.
• template.yaml - Configuration of SAM, where you can define your resources. You must declare and configure all your Lambda functions here. The application uses several AWS resources, including Lambda functions and an API Gateway API. These resources are defined in the template.yaml file in this project. You can update the template to add AWS resources through the same deployment process that updates your application code.
• samconfig.toml - Another configuration file about the project.

Fetch, tail, and filter Lambda function logs

To simplify troubleshooting, SAM CLI has a command called sam logs. sam logs lets you fetch logs generated by your deployed Lambda function from the command line. In addition to printing the logs on the terminal, this command has several nifty features to help you quickly find the bug.

NOTE: This command works for all AWS Lambda functions; not just the ones you deploy using SAM.

sam logs -n HelloWorldFunction --stack-name lambda-docker-prototype --tail

You can find more information and examples about filtering Lambda function logs in the SAM CLI Documentation.