In order to be able to debug Node.js with TypeScript in a Docker container (or in general: debug remote) using WebStorm, compilerOptions in your tsconfig.json need to contain inlineSources and inlineSourceMap being set to true.

So your tsconfig.json might look like this:

{
  "compilerOptions": {
    "outDir": "build",
    "inlineSources": true,
    "inlineSourceMap": true
  },
  "include": [
    "src/**/*"
  ],
  "exclude": [
    "**/*.spec.ts"
  ]
}