How to build TypeScript mono-repo project deploy in micros

This repository explains how to create a mono-repo using microservice instead of a monolithic approach

That repository is a mirror example for this entry https://medium.com/p/6a13454937ab/edit

Directory Structure

- applications/ : contains all microservices instance
- lib/ : contains all microservices common libraries 
- applications/**/build/ : contains the build information for the microservice deploy
- docker-compose.yml : example of start a cluster of microservices

Tools

- NPM (v7 or higher) Workspaces
- eslint.js
- husky
- TypeScript
- Docker

NPM CLI

• We can create a workspace entry using the same code

  npm init -w ./applications/user-service

• We can order installation to all workspace items

  npm install --workspaces express winston mocha chai

• We can order install to specific workspace items

  npm install -D @types/express -w user-service

Package JSON Script

The scripts in the parent folder that I propose are the next:

    "build-all": "npm run build --workspaces --if-present",
    "install-all": "npm install --workspaces  --if-present",
    "lint-all": "npm run lint --workspaces --if-present",
    "lint-fix-all": "npm run lint-fix --workspaces --if-present"

for each of these parent script you need a child script that does the same, for example in user-service package.json

  "scripts": {
    "start": "node .",
    "build": "tsc",
    "lint": "eslint src",
    "lint-fix": "eslint src --fix"
  }

Eslint Requirement

Eslint inheritance is setting from the parent, if you don't put the key "root" in the file, eslint is going to find in the parent folder the eslint file... so we could create in the parent folder an eslint configuration.

https://eslint.org/docs/user-guide/configuring/configuration-files#cascading-and-hierarchy

The configuration is the next, for parent root

{
    "root": true, // important
    "parser": "@typescript-eslint/parser",
    "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/eslint-recommended",
        "plugin:@typescript-eslint/recommended"
    ],
    "plugins": ["workspaces", "@typescript-eslint"],
    "ignorePatterns": ["**/**/dist/*.{js,ts}"],
    "rules": {
        "workspaces/no-relative-imports": "error",
        "workspaces/require-dependency": "warn"
    }
}

for a child, we only need an empty .eslintrc file

{}

TypeScript requirements

TypeScript Config

TypeScript provides a mono-repo feature, for that, you could have a main tsconfig.json root config and in each TS subproject you could extends this configuration

(/tsconfig.json)

{
  "compilerOptions": {
    "target": "es2016",
    "module": "commonjs",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "skipLibCheck": true,
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,
    "allowSyntheticDefaultImports": true,
  }
}

(/applications/user-service/tsconfig.json)

{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "outDir": "./dist"
  },
  "references": [
    {
      "path": "../../libs/hello-i18n"
    }
  ]
}

TypeScript references

For reuse libraries in other TypeScript projects, you need to create a reference in the tsconfig.json

(/applications/user-service/tsconfig.json)

{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "outDir": "./dist"
  },
  "references": [
    {
      "path": "../../libs/hello-i18n"
    }
  ]
}

like this of user-service, but we need to take care of put these attributes in the package.json of the lib you are using

  "main": "dist/index.js",
  "files": [
    "src",
    "dist"
  ]