Lambda on The Edge Cases

Building Docker Images on M1 Mac for Other Platforms

Sat, 19 Sep 2026 02:10:03 +0000

In order to build Docker images for Lambda functions with CDK on ARM or other non-Intel platforms, but want the Lambda to be on an x86_64 platform, use the platform parameter with the from_image_asset() function.

_lambda.DockerImage_function(
    ...
    code=_lambda.DockerImageCode.from_image_asset(  
        directory="./lambda",  
        file="./myservice/Dockerfile",  
        platform=ecr_assets.Platform.LINUX_AMD64,  
    ),
    ...
)

ecr_assets is a CDK package that also needs to be imported from the main aws_cdk package.

Fixing Runtime Exited Without a Reason Errors in AWS Lambda

Thu, 25 May 2023 18:47:46 +0000

This happens sometimes with Dockerized Lambdas. I have no idea why, but fixing it usually consists of rebuilding and re-pushing the docker image, redeploying it to the Lambda, and re-running it.

Deploying an Updated Image to Lambda Function

Wed, 04 Jan 2023 18:24:48 +0000

Redeploying a CDK stack with a Lambda function that relies on a Docker image in ECR won’t necessarily update the function with a newly pushed image. Instead, use the Lambda console’s “Deploy new image” button to push the ECR image to the function.

Raising Exceptions from Lambda to API Gateway Caller

Wed, 05 Oct 2022 17:09:29 +0000

You can send exception feedback from a Lambda to an API Gateway API either by raising a Python exception and handling it via a mapping template, or return a specific set of values from the main handler function.

Returning from the Handler Function

You can return a dictionary that includes at least:

the desired status code
the message body (JSONified)
and whether or not the body is base64 encoded

return {  
    "statusCode": 404,  
    "body": simplejson.dumps(  
        f"User {username} not found"  
    ),  
    "isBase64Encoded": False,  
}

Raising an Exceptions

Using a mapping template allows you to simply use regex to associate an error message from a plain Python exception with a certain HTTP code. I don’t have any examples because I haven’t done it, preferring the previous method.

Including Assets from Parent Directories in Dockerized Lambda Functions with CDK

Tue, 04 Oct 2022 17:31:19 +0000

If you have a Docker based Lambda that is defined in some directory and there are assets that the Lambda needs in the parent directory, from_image_asset() takes directory and file parameters, so you can select the parent directory as well as the specific Dockerfile that describes the environment for the Lambda.

Here is an example folder structure:

CDK_infrastructure/
    lambdas/
        lambda_one.py
        lambda_two.py
        lambda_pkg/
            ...
        docker_lambda/
            Dockerfile

And here is how you would set this up in your stack definition:

Asynchronous Lambda Invocation

Tue, 30 Aug 2022 18:57:17 +0000

In order to invoke a Lambda asynchronously, pass InvocationType="Event" to the invoke call. This is useful for, among other things, a hub/message routing Lambda that calls other ones in a fire-and-forget manner. ¹

Source

Lambda API Invoke AWS Documentation

This is likely not an ideal architecture, there are usually better alternatives ↩︎

AWS Lambda Return Values for API Triggering

Mon, 07 Feb 2022 21:41:05 +0000

A Lambda triggered by an API has to return a dictionary with certain keys and values in order to not cause an error in execution (e.g. “malformed lambda proxy response”). These are the status code, body (JSONified), and if it’s base64 encoded. Headers can also be added to this structure, but they don’t seem required.

Code Example

    return {  
      "statusCode": 200,  
   "body": json.dumps(f"User {username} not found"),  
   "isBase64Encoded": False  
  }

Sources

Passing Secrets into Lambdas in CDK

Mon, 07 Feb 2022 18:43:52 +0000

same: AWS Lambda Return Values for API Triggering, To Build a Lambda from a Dockerfile in CDK

Passing Secrets into Lambdas in CDK

Do not pass Secret Manager values via environment variables in your CDK Stack! This is a problem for two reasons:

This exposes the Secret in the generated CF templates.
This only pulls the Secret value at deploy time only if the Secrets construct or Lambda in question will be rebuilt upon deploy or synthesis. If the keys are rotated, and the constructs in the CDK stack aren’t changed, this won’t be picked up by the app.

To address this, handle Secret Manager secrets in the following way:

To Build a Lambda from a Dockerfile in CDK

Wed, 27 Oct 2021 19:24:41 +0000

Creating the Dockerfile

To set up a Dockerfile for a Lambda function that relies on non-AWS base images, you have to include the Python package awslambdaric in your requirements and install it. Then, do the following in the Dockerfile:

ENTRYPOINT [ "/usr/local/bin/python", "-m", "awslambdaric" ]  
CMD ["lambda_code.function_name"]

Example

ARG FUNCTION_DIR="/function"
  
FROM tensorflow/tensorflow:2.4.3 as DEV  
ARG FUNCTION_DIR  
RUN mkdir -p ${FUNCTION_DIR}
## copies python code into container's FUNCTION_DIR
COPY lambda_code.py ${FUNCTION_DIR} 
## copies lambda_requirements.txt into container's requirements.txt
COPY lambda_requirements.txt ./requirements.txt  
## copies dataset into container's FUNCTION_DIR/dataset/
COPY dataset ${FUNCTION_DIR}/dataset/  
RUN pip install --no-cache-dir --upgrade pip && \  
    pip install -r requirements.txt --target ${FUNCTION_DIR}  
WORKDIR ${FUNCTION_DIR}  
ENTRYPOINT [ "python", "-m", "awslambdaric" ]  
CMD ["lambda_code.function_name"]

Setting Up the Lambda in CDK

To create a Lambda from a Dockerfile in CDK, use cdk.aws-lambda.DockerImageFunction when defining your Lambda: