Lambda cold start when asset sharing

Hi,

I'm not sure if I understand you correctly, but if you mean building a monolithic Lambda function that would handle multiple or all API Gateway routes, note that according to AWS, it is considered an anti-pattern for the following reasons:

• Package size: the Lambda function may be much larger because it contains all possible code for all paths, which makes it slower for the Lambda service to download and run.
• Hard to enforce least privilege: the function’s IAM role must allow permissions to all resources needed for all paths, making the permissions very broad. Many paths in the functional monolith do not need all the permissions that have been granted.
• Harder to upgrade: in a production system, any upgrades to the single function are more risky and could cause the entire application to stop working. Upgrading a single path in the Lambda function is an upgrade to the entire function.
• Harder to maintain: it’s more difficult to have multiple developers working on the service since it’s a monolithic code repository. It also increases the cognitive burden on developers and makes it harder to create appropriate test coverage for code.
• Harder to reuse code: typically, it can be harder to separate reusable libraries from monoliths, making code reuse more difficult. As you develop and support more projects, this can make it harder to support the code and scale your team’s velocity.
• Harder to test: as the lines of code increase, it becomes harder to unit all the possible combinations of inputs and entry points in the code base. It’s generally easier to implement unit testing for smaller services with less code.

Thus, the recommendation is to map a single Lambda function to a single, well-defined task. For more information, take a look to the previously attached documentation, it's really good.