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https://github.com/kilna/python-lambda-docker

Lightweight docker image for running, testing, packaging and deploying python-based AWS lambda functions
https://github.com/kilna/python-lambda-docker

amazon aws aws-lambda aws-lambda-python docker-image dockerfile lambda python python-lambda

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Lightweight docker image for running, testing, packaging and deploying python-based AWS lambda functions

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# python-lambda-docker



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[![](https://img.shields.io/badge/python-2.7,_3.6-blue.svg?style=plastic)](https://github.com/kilna/python-lambda-docker/)



Lightweight docker image for running, testing, packaging and deploying python-based AWS lambda functions



## Links



* Docker: [python-lambda](https://hub.docker.com/r/kilna/python-lambda/)

* GitHub: [python-lambda-docker](https://github.com/kilna/python-lambda-docker)

* Based on the [python-lambda library](https://github.com/nficano/python-lambda/) by [nficano](https://github.com/nficano/)



## Purpose



I needed a Docker-based environment in which to host AWS python lambda functions for the purpose of testing and building them... python-lambda works well under virtualenv for development, but build and deployment automation require a clean and reproducible environment to operate in. Our CI system already supported Docker as a containerization system, so it was the obvious choice.



In order to use this, you will have your project derive its own Dockerfile based on a base python-lambda image corresponding to which version of Python you wish to run.



## Usage



An example of a usable project can be found in the [example/](./example/) directory.  The lambda function in [service.py](./example/service.py) takes a JSON input file like the one provided in [event.json](./example/event.json) and returns an ASCII-art version of the text described in it.  The [Dockerfile](./example/Dockerfile) derives from python-lambda as a base image, and loading the example directory contents into the image at the path _/lambda_, then installs dependencies from the [requirements.txt](./example/requirements.txt) file.  



### Building a Derived Docker Image



To build a docker image from the provided [example/](./example) called _example-lambda-image_ with the ASCII-art lambda function in it, run:



```

$ cd example/

$ docker build --tag example-lambda-image .

```



Any time you make changes to the example project, you'll need to re-run the `docker build` command above, or you can investigate using docker volumes to sync local filesystem changes into the container. 



#### Switching Python Versions



The example [Dockerfile](./example/Dockerfile) uses a _:latest_ docker tag in the FROM line, which is currently the same as _:3.6_, but if you wish to use a different Python version you can change this. Supported Python versions are 2.7 and 3.6. To use Python version 2.7 change the first line of the example [Dockerfile](./example/Dockerfile) to:



```

FROM kilna/python-lambda:2.7

```



You will also need to change the following line in [config.yaml](./example/config.yaml)



```

runtime: python2.7

```



### Executing the Lambda Function



If you want to execute the lambda function against the [event.json](./example/event.json) input file:



```

$ docker run example-lambda-image lambda invoke

 _  _     _ _                        _    _ _

| || |___| | |___    __ __ _____ _ _| |__| | |

| __ / -_) | / _ \_  \ V  V / _ \ '_| / _` |_|

|_||_\___|_|_\___( )  \_/\_/\___/_| |_\__,_(_)

                 |/

```



### Building and Testing the Lambda Function



If you would like to build the lambda function (which will package the function and all its dependencies), run:



```

$ docker run example-lambda-image lambda build

```



The result will be a zip file created in the /lambda/dist directory inside the container.



If you would like to build and _test_ the lambda function and gather up the results, you can run:



```

$ docker run example-lambda-image lambda_build_tar | tar -x -v

build.log

test.log

dist/

dist/2017-09-01-003647-example-lambda.zip

```



Behind the scenes, what this does is:



* Removes any log and dist files from prior runs

* Executes 'lambda build' and stores the log in _/lambda/build.log_ in the container

* If present and executable, runs _/lambda/run_tests_ and stores the log in /lambda/test.log in the container

* Tars the log files, and the contents of the dist directory in /lambda on the container and pipes it to standard output

* Untars the contents bundled up within the container, and extracts them into your current directory



### Deploying the Lambda Function



You can deploy your lambda function to Amazon's infrastructure...  you'll need to add AWS credentials into the [config.yaml](./example/config.yaml) file. Alternately, if your local AWS CLI environment is working, you can add a _.aws/_ directory (you can `cp ~/.aws`) into the _example/_ directory), then re-build your image. Once AWS is working within your container, you can then run the following to deploy your function to Amazon:



```

$ docker run example-lambda-image lambda deploy

```