I export one function called 'handler' in js and I'm confident that it is being called correctly. Some environment checking code was throwing exceptions correctly, I fixed the env and then got this error.

is this script maybe trying to be loaded as a module? ESM?

what is the full error? what is the build config?

did you include the node_modules when bundling? assuming you use any npm packages?

is there more than one error and maybe this one a symptom of the other?

I haven't included the node_modules. I thought the closure compiler included necessary dependencies. While I haven't added any node_modules, shadow-cljs has quite a few. Should I include all node_modules?

no, you only need to include the packages you actually use. you can also post-process the release build with something like https://github.com/vercel/ncc to bundle all npm dependencies

shadow-cljs does not do that by default since generally it is not required or desirable for regular node builds

Thank you for the help btw. 🙂 Very much appreciated. Shadow is ⭐

My build config looks like this:

:builds
 {:lambda {:target :node-library
           :exports {:handler com.pds.external-api.core/handler}
           :output-to "target/lambda.mjs"
           :compiler-options {:output-feature-set :es2020}}}

Does something not look right?

well the hint seems to be that you have :output-to "target/lambda.mjs" meaning its expected to be a ES module?

:node-library outputs commonjs so that won't work

if it must be a module use :target :esm https://shadow-cljs.github.io/docs/UsersGuide.html#target-esm

or just :output-to "target/lambda.js" and just run without modules?

changing the build target to .js worked perfectly. Thank you! I copied that entry from an example without understanding the significance.

So when I package the zip file, I should take care to include my own node_modules and their deps? Can shadow help me determine those deps or should I figure them out via dep trees and select what to zip?

or should I just take everything in node_modules?

FYI: transitive dependencies for any top level node package can be listed with npm ls -a --json | jq --arg v 'shadow-cljs' '[ .dependencies | .[$v] | .dependencies | .. | .dependencies? | objects | to_entries[] | .key ] | sort | unique' and changing the value of --arg v

me recommendation is either post processing with ncc to get a completely standalone .js file

or creating a dedicated directory that has its own package.json and only includes the packages you actually need in production

and the build output going into that dir and then just zipping that entire dir

That's great advice. Thank you