Regression: Version 3.49.0 and upwards are not able to parse serverless.ts when using tsconfig.paths

[AlesioSinopoli]

Hi all,

A bug/regression was introduced in version 3.49.0. Previous versions were able to successfully parse serverless.ts config files that have imports which rely on tsconfig paths.

Details

At the top of my serverless.ts file I have the following import statement:

import { apiGatewayResources } from '@/resources/apigateway/serverless';

In my tsconfig.json file I have the following paths configuration:

"paths": {
      "@/database/*": ["src/database/*"],
      "@/helpers/*": ["src/helpers/*"],
      "@/libs/*": ["src/libs/*"],
      "@/services/*": ["src/services/*"],
      "@/testing/*": ["src/testing/*"],
      "@/types/*": ["src/types/*"],
      "@/v1/*": ["src/v1/*"],
      "@/v2/*": ["src/v2/*"],
      "@/resources/*": ["resources/*"],
      "@/migrations/*": ["src/migrations/*"]
    }

When I run sls offline start, I get the following error:

Error:
Cannot parse "serverless.ts": Initialization error: Error: Cannot find module '@/resources/apigateway/serverless'
Require stack:
- /Users/alesio.sinopoli/Desktop/Projects/api/serverless.ts
    at Function._resolveFilename (node:internal/modules/cjs/loader:1244:15)
    at Function.resolve (node:internal/modules/helpers:146:19)
    at jitiResolve (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/jiti/dist/jiti.cjs:1:187220)
    at jitiRequire (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/jiti/dist/jiti.cjs:1:189288)
    at import (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/jiti/dist/jiti.cjs:1:199778)
    at /Users/alesio.sinopoli/Desktop/Projects/api/serverless.ts:1:218
    at eval_evalModule (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/jiti/dist/jiti.cjs:1:196325)
    at jitiRequire (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/jiti/dist/jiti.cjs:1:190233)
    at Function.import (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/jiti/dist/jiti.cjs:1:199778)
    at parseConfigurationFile (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/osls/lib/configuration/read.js:62:42)
    at module.exports (/Users/alesio.sinopoli/Desktop/Projects/api/node_modules/osls/lib/configuration/read.js:145:29)
    at /Users/alesio.sinopoli/Desktop/Projects/api/node_modules/osls/scripts/serverless.js:186:28
    at /Users/alesio.sinopoli/Desktop/Projects/api/node_modules/osls/scripts/serverless.js:194:13

Root cause of the regression

The following PR #30 made changes to how the serverless.ts config file is parsed. It removes ts-node and introduces jiti instead.

At the moment, jiti does not support tsconfig.paths, so it's unable to parse any files that contains import paths defined in that way.

Closing Thoughts?

Many developers use tsconfig.paths in their projects. This change can affect their experience and make them unable to upgrade to newer versions of osls without re-factoring code and dropping their tsconfig.paths entirely.

Not sure what can be done to solve the problem at the moment without reverting the new feature introduced in 3.49.0, besides waiting until jiti adds support for tsconfig.paths.

[bgc-gustavo-vieira]

I am having the same issue. Any updates?

[mnapoli]

@zirkelc any idea to work around this? Or should we revert #30?

[zirkelc]

Let me take a look and come back to you. It looks like Jiti alias is an alternative, but need to check it first.

I would prefer to avoid reverting to ts-node, because it would break ESM support and the latest ts-node release is more than two years ago. That means ts-node doesn't support modern features like extending from multiple tsconfigs "extends": ["tsconfig.paths.json", "tsconfig.root.json"] (TypeStrong/ts-node#1954).

Is pinning the version to 3.48.0 a possible workaround for the time being until I investigated this issue? @bgc-gustavo-vieira @AlesioSinopoli

[zirkelc]

I went another way and use tsx (https://tsx.is/dev-api/tsx-require) to load the serverless.ts as it resolves typescript aliases. I confirmed it locally and I'm currently trying to add a unit test for it.

In the meantime, please have a look here and test if it works for you:

#68

Depending on your package manager, you might be able to install this PR directly:
https://stackoverflow.com/questions/33181297/npm-install-from-github-pull-request

@mnapoli in some of my repos, I use https://github.com/stackblitz-labs/pkg.pr.new to make PR installable. This GitHub app adds a comment to the pull request which is updated on every commit. It's super convenient for testing PRs without publishing to npm. What do you think about adding it to this repo? I can submit a small PR with a new github workflow if you want.