Run Typescript application with PM2

Question

I have an application written in Typescript that runs with PM2. Currently I compile to JavaScript, then use PM2 to start the app. My ecosystem.config.js file looks like this:

module.exports = {
  apps: [
    {
      name: 'My Application',
      script: './dist/server/index.js',
      env_qa: {
        PORT: 3001,
        NODE_ENV: 'production',
      },
      env_production: {
        PORT: 3000,
        NODE_ENV: 'production',
      },
    },
  ],
};

I run this with the command:

pm2 stop ecosystem.config.js --env qa

When developing, I just run ts-node server instead of compiling and using PM2. I recently read that ts-node has a 'transpileOnly' or 'fast' mode meaning it can be used in production. Firstly, I'd like to know if it's true that this can be used in production environments. Secondly, how would I still use PM2 to launch my app but using ts-node?

Answer 1

The package.json script should be like below:

package.json file (containing below example scripts)

"scripts": {
    "shivkumarscript": "ts-node -T -P server/tsconfig.json server/index.ts"
  }

ecosystem.config.json file

module.exports = {
    apps: [
        {
            name: "NodeServer",
            script: "npm",
            automation: false,
            args: "run shivkumarscript",
            env: {
                NODE_ENV: "development"
            },
            env_production: {
                NODE_ENV: "production"
            }
        }
    ]
}

Assuming that you have already installed Node.js, NPM and PM2 on your machine. Then below should be the command to start the application through pm2 which will in turn run the npm script (command line mentioned in your application's package.json file):

For production environment:

pm2 start ecosystem.config.js --env production --only NodeServer

For development environment:

pm2 start ecosystem.config.js --only NodeServer

...And Boooom! guys

Answer 2

Dev environment

Runtime which leads to extremely high memory consumption and server overload, in the end, so it cannot be used on production, link https://pm2.io/docs/runtime/integration/transpilers/

  "scripts": {
    "pm2": "NODE_ENV=production pm2 start server.ts --watch"
  }

Production use

Transpile typescript to javascript with a separate command and run it using npm run pm2 and npm run pm2:staging if you have a staging environment.

The commands npm run prod and npm run staging used only locally when I need to work locally with production and staging environments.

  "scripts": {
    "pm2": "NODE_ENV=production pm2 start build/server.js --watch -i max",
    "pm2:staging": "NODE_ENV=staging pm2 start build/server.js --watch -i max",
    "prod": "NODE_ENV=production node build/server.js",
    "staging": "NODE_ENV=staging node build/server.js",
    "dev": "HTTPS=true NODE_ENV=development ts-node-dev --inspect --respawn src/server.ts",
    "test": "NODE_ENV=test nyc ./node_modules/.bin/mocha --require ts-node/register ./src/test/**/**/**/**/*.test.ts",
    "build": "rimraf build && tsc -p tsconfig.json"
   }

tsconfig.json

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es5" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
    "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
    "lib": [
      "es2015", "dom"
    ] /* Specify library files to be included in the compilation. */,
    // "allowJs": true,                       /* Allow javascript files to be compiled. */
    // "checkJs": true,                       /* Report errors in .js files. */
    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
    "sourceMap": true /* Generates corresponding '.map' file. */,
    // "outFile": "./",                       /* Concatenate and emit output to single file. */
    "outDir": "./build" /* Redirect output structure to the directory. */,
    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
    // "composite": true,                     /* Enable project compilation */
    // "removeComments": true,                /* Do not emit comments to output. */
    // "noEmit": true,                        /* Do not emit outputs. */
    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */

    /* Strict Type-Checking Options */
    "strict": true /* Enable all strict type-checking options. */,
    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
    // "strictNullChecks": true,              /* Enable strict null checks. */
    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
    "strictPropertyInitialization": false,  /* Enable strict checking of property initialization in classes. */
    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */

    /* Additional Checks */
    "noUnusedLocals": true /* Report errors on unused locals. */,
    "noUnusedParameters": true /* Report errors on unused parameters. */,
    "noImplicitReturns": true /* Report error when not all code paths in function return a value. */,
    "noFallthroughCasesInSwitch": true /* Report errors for fallthrough cases in switch statement. */,

    /* Module Resolution Options */
    "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
    // "typeRoots": [],                       /* List of folders to include type definitions from. */
    "types": ["reflect-metadata"],
    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
    "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */,
    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */

    /* Source Map Options */
    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
    "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */

    /* Experimental Options */
    "experimentalDecorators": true,           /* Enables experimental support for ES7 decorators. */
    "emitDecoratorMetadata": true,             /* Enables experimental support for emitting type metadata for decorators. */
    "skipLibCheck": true
  }
}

PM2 can generate startup scripts and configure them in order to keep your process list intact across expected or unexpected machine restarts, which is important to keep automated, link https://pm2.keymetrics.io/docs/usage/startup/

pm2 unstartup
pm2 startup
pm2 save