How to debug a Node.js server written in TypeScript running in Docker

docker-compose.yml

version: "3"

services:
  server:
    command: npm run debug
    build: .
    volumes:
      - ./dist/src:/server/dist/src/ # same folder structure on local machine and docker container
    ports:
      - "3001:3001" # open port for server api
      - "9222:9222" # open port for inspector to debug

Dockerfile

FROM node:10.8.0-alpine
WORKDIR /server
COPY package.json package-lock.json ./
RUN npm ci
COPY . /server
CMD [ "npm", "run", "start" ]

gulpfile.js

const gulp = require("gulp");
const ts = require("gulp-TypeScript");
const sourcemaps = require("gulp-sourcemaps");
const filter = require("gulp-filter");
const watch = require("gulp-watch");
const rimraf = require("rimraf");

const tsProject = ts.createProject("./tsconfig.json");

gulp.task("transpile", () => {
  const tsResult = tsProject
    .src()
    .pipe(sourcemaps.init())
    .pipe(tsProject(ts.reporter.fullReporter()))
    .on("error", () => null);

  return tsResult.js.pipe(sourcemaps.write("./")).pipe(gulp.dest("./dist/src"));
});

gulp.task("watch-server", ["transpile"], function() {
  return watch(["src/**/*.{ts,tsx}"], function() {
    gulp.start("transpile");
  });
});

gulp.task("initial-clean", function(done) {
  rimraf("./dist", done);
});

gulp.task("start-watch", ["initial-clean"], () => {
  gulp.start("watch-server");
});

gulp.task("watch", ["start-watch"]);

tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "types": ["@types/node", "node"],
    "typeRoots": ["./node_modules/@types"],
    "lib": ["es5", "es6", "es2015"],
    "rootDir": "src",
    "outDir": "dist", // specify the directory for your compiled code
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "moduleResolution": "node"
  },
  "include": ["src/**/*.ts"],
  "exclude": ["node_modules", "dist"]
}