AWS Lambda : how to handle a code asset defined by an environment variable that does not exist yet?

Question

I (try to) deploy my current application using CDK pipelines.

In doing so, I stumbled across an unexpected behavior (here if interested) which now I am trying to resolve. I have a Lambda function for which the asset is a directory that is dynamically generated during a CodeBuild step. The line is currently defined like this in my CDK stack :

code: lambda.Code.fromAsset(process.env.CODEBUILD_SRC_DIR_BuildLambda || "")

The issue is that locally, this triggers the unexpected and undesired behaviour because the environment variable does not exist and therefore goes to the default "".

What is the proper way to avoid this issue?

Thanks!

fedonev · Accepted Answer · 2022-02-06 12:16:52Z

1

Option 1: Set the env var locally, pointing to the correct source directory;

CODEBUILD_SRC_DIR_BuildLambda=path/to/lambda && cdk deploy

Option 2: Define a dummy asset if CODEBUILD_SRC_DIR_BuildLambda is undefined

code: process.env.CODEBUILD_SRC_DIR_BuildLambda
  ? lambda.Code.fromAsset(process.env.CODEBUILD_SRC_DIR_BuildLambda)
  : new lambda.InlineCode('exports.handler = async () => console.log("NEVER")'),

answered Feb 6, 2022 at 12:16

fedonev

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4 Comments

FenryrMKIII Over a year ago

Yeah that is one possibility. I was just wondering how ‘state of the art’ this is.

fedonev Over a year ago

@FenryrMKIII This problem does not arise in CDK "state of the art", because Infrastructure and runtime code live in the same package.

FenryrMKIII Over a year ago

Yes, I have seen this article. But in my business case, we work with contractors and they have the repo for the application while we own the repo for the infra. So how should we do? Use GitHub submodule capacities to reach this situation of one repo for infra and code ?

fedonev Over a year ago

@FenryrMKIII It's OK for atypical use cases like yours to deviate from "best practices", which are for standard scenarios. I was just answering the questions as written.

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