Deploy Python Lambda Functions With Container Image

You can deploy your Lambda function code as a container image. AWS provides the following resources to help you build a container image for your Python function:

• AWS base images for Lambda

  • These base images are preloaded with a language runtime and other components that are required to run the image on Lambda. AWS provides a Dockerfile for each of the base images to help with building your container image.

• Open-source runtime interface clients

  • If you use a community or private enterprise base image, add a runtime interface client to the base image to make it compatible with Lambda.

What’s In This Document

• Create Docker image container
• Create app.py as lambda handler
• Build and push the image to ECR
• Create Lambda container image
• Test the lambda function

🚀 Create Docker image container

Create an image from AWS base image

Dockerfile.aws

FROM amazon/aws-lambda-python:3.8

COPY app.py ./

CMD ["app.handler"]

🚀 Create app.py as lambda handler

import sys


def handler(event, context):
    return 'Hello from AWS Lambda using Python' + sys.version + '!'

🚀 Build and push the image to ECR

aws ecr get-login-password --region ap-southeast-1 | docker login --username AWS --password-stdin 111111111111.dkr.ecr.ap-southeast-1.amazonaws.com
docker build -t pythonlambda .
docker tag pythonlambda:latest 111111111111.dkr.ecr.ap-southeast-1.amazonaws.com/pythonlambda:latest
docker push 111111111111.dkr.ecr.ap-southeast-1.amazonaws.com/pythonlambda:latest

🚀 Create Lambda container image

🚀 Test the lambda function

1. Invoke lambda function

• Start container ```

docker rm -f lambdaimagetest
docker run -d --name lambdaimagetest -it pythonlambda:latest bash
docker exec -it lambdaimagetest bash

- Invoke lambda function

⚡ $ aws lambda invoke --function-name python-lambda-image --region ap-southeast-1 outfile

{
"StatusCode": 200,
"ExecutedVersion": $LATEST"
}
⚡ $ cat outfile

"Hello from AWS Lambda using Python3.8.5 (default, Aug 5 2020, 08:22:02) \n[GCC 8.3.0]!"

#### **2. Call lambda API from local container**
- This should be performed from AWS image base
- Run container

⚡ $ docker run -d --name testapi -p 9000:8080 pythonlambda:latest

- Call API

⚡ $ curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'
"Hello from AWS Lambda using Python3.8.6 (default, Dec 16 2020, 01:05:15) \n[GCC 7.3.1 20180712 (Red Hat 7.3.1-11)]!"

- Deploy new image
![Alt Text](https://dev-to-uploads.s3.amazonaws.com/i/bdrihq86bqmtnm4ei5xe.png)
- Invoke lambda function

⚡ $ aws lambda invoke --function-name python-lambda-image --region ap-southeast-1 outfile

{
"StatusCode": 200,
"ExecutedVersion": "$LATEST"
}
⚡ $ cat outfile
"Hello from AWS Lambda using Python3.8.6 (default, Dec 16 2020, 01:05:15) \n[GCC 7.3.1 20180712 (Red Hat 7.3.1-11)]!"

**Mirror**:
- https://github.com/vumdao/lambda-container-image
- https://vumdao.hashnode.dev/deploy-python-lambda-functions-with-container-image

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Comments

[ymmark01]

Hi, when testing with curl, where does the path "2015-03-31/functions/function/invocations" come from?

[🚀 Vu Dao 🚀]

That API path is in the container image where there's process listens to, you should have a check

[Jason Yuen]

I am trying to follow step 1 but getting this os.environ error. Any help would be greatly appreciated.

File "/usr/local/lib/python3.8/runpy.py", line 194, in run_module_as_main
return _run_code(code, main_globals, None,
File "/usr/local/lib/python3.8/runpy.py", line 87, in _run_code
exec(code, run_globals)
File "/usr/local/lib/python3.8/site-packages/awslambdaric/main.py", line 21, in
main(sys.argv)
File "/usr/local/lib/python3.8/site-packages/awslambdaric/main.py", line 14, in main
lambda_runtime_api_addr = os.environ["AWS_LAMBDA_RUNTIME_API"]
File "/usr/local/lib/python3.8/os.py", line 675, in __getitem_
raise KeyError(key) from None
KeyError: 'AWS_LAMBDA_RUNTIME_API'

[Cherny]

you should use aws-lambda-rie (emulator) instead of aws-lambda-ric - docs.aws.amazon.com/lambda/latest/.... I believe that environment variable is set by AWS, so if it's not present that script will execute the emulator. This is an example

entry_script.sh

#!/bin/sh

if [ -z "${AWS_LAMBDA_RUNTIME_API}" ]; then
    exec /usr/local/bin/aws-lambda-rie /usr/local/bin/python -m awslambdaric $@
else
    exec /usr/local/bin/python -m awslambdaric $@
fi

Dockerfile

FROM python:3.9-bullseye

ARG FUNCTION_DIR="/function"
WORKDIR ${FUNCTION_DIR}

RUN curl -Lo /usr/local/bin/aws-lambda-rie \
    https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie && \
    chmod +x /usr/local/bin/aws-lambda-rie

COPY entry_script.sh ${FUNCTION_DIR}

# Install dependencies
RUN pip install \
    --target ${FUNCTION_DIR} \
    awslambdaric

# Copy function code
COPY src/* ${FUNCTION_DIR}

ENTRYPOINT [ "sh", "entry_script.sh" ]
CMD [ "app.handler" ]

[🚀 Vu Dao 🚀]

Hi Jason,

I guess you're trying to build lambda image from alternative base image but I recommend to use image base from AWS such as public.ecr.aws/lambda/python:3.8 or amazon/aws-lambda-python:3.8

For your issue, you're missing setting ENV AWS_LAMBDA_RUNTIME_API=, this variable env must be defined but you will still get following error after that

  File "/function/awslambdaric/lambda_runtime_client.py", line 76, in wait_next_invocation
    response_body, headers = runtime_client.next()
RuntimeError: Failed to get next