AWS/Sam CodeURI and Handler specification issues

Question

I have been having all kinds of problems using/specifying CodeUri and Handler specifications consistently.

It is my understanding that the way it supposed to work is that if you have a source tree of
    `/src/api/...` and `/src/lib/...`
etc., you should be able to specify  `CodeUri: src/` and then the handlers can be specified as `Handler: api....app.lambda_handler` alleviating the need to prefix everything with `src`.  This then holds true for any files we access from within a handler -- i.e., the path(s) to a template file like `"./src/lib/categories/all.json"` should be able to be referenced as `"./lib/categories/all.json"`

I have had it happen that the first function defined can use `CodeUri: src/` but the remaining functions won't work unless `CodeUri:` is removed and then the handlers are specified as `Handler: src.api...app.lambda_handler`. (It does not matter if you specify '.' or '/' as the delimiter in the `Handler` syntax.)

Furthermore, for the instance where the first function was able to use `CodeUri: src/`  we found that when deployed into a different AWS/Sam stack/container by my colleague, it no longer accepted the `CodeUri` specification and we had to revert everything to use the `Handler: src.api...app.lambda_handler` form to get it to work across deployment containers.

So, my questions is "What am I missing regarding using `CodeUri` and `Handler` specifications, or my `template.yaml` in general, to make this more usable and consistent?.  Any help would be appreciated.

Answer

Your project, and therefore, your template file, may include multiple Lambda functions, each in its own sub folder. You usually place your template.yaml file in the root of the project, i.e., `/template.yaml`.

If your functions are located in `/src/function1` and `/src/function2,` you will use in the `CodeUri` the root of the function itself, i.e., for the first function you will specify `/src/function1` and for the second `/src/function2`. For the `Handler` you will specify the name of the file and the name of the handler, e.g., `app.lambda_handler` (where `app.py` is the file that contains the handler function, which is called `lambda_handler`)

AWS/Sam CodeURI and Handler specification issues

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