dependencies.html.md.erb

---
title: Declare App Dependencies
owner: Tobias Fuhrimann
---

<strong><%= modified_date %></strong>

<%= vars.product_short %> recognizes an app as Node.js by the existence of a `package.json` file in the root directory. For your own apps, you can create one by running `npm init`.

The demo app you deployed already has a `package.json`, and it looks something like this:

```json
{
  "name": "cf-sample-app-nodejs",
  "description": "A sample Node.js application to run on Cloud Foundry out of the box",
  "keywords": [
    "cloud-foundry"
  ],
  "version": "0.0.0",
  "private": true,
  "author": "Tobias Fuhrimann <tobias.fuhrimann@swisscom.com>",
  "license": "ISC",
  "scripts": {
    "start": "node ./bin/www"
  },
  "dependencies": {
    "body-parser": "~1.15.0",
    "cookie-parser": "~1.4.1",
    "debug": "~2.2.0",
    "express": "~4.13.4",
    "morgan": "~1.7.0",
    "pug": "^2.0.0-alpha3",
    "serve-favicon": "~2.3.0"
  },
  "engines": {
    "node": ">=4.4.2"
  },
  "repository": {
    "type": "git",
    "url": "https://github.com/swisscom/cf-sample-app-nodejs.git"
  },
  "bugs": {
    "url": "https://github.com/swisscom/cf-sample-app-nodejs/issues"
  }
}
```

The `package.json` file determines both the version of Node.js that will be used to run your application on <%= vars.product_short %>, as well as the dependencies that should be installed with your application. When an app is deployed, <%= vars.product_short %> reads this file and installs the appropriate node version together with the dependencies using the `npm install` command.

Run this command in your local directory to install the dependencies, preparing your system for running the app locally:

<pre class="terminal">
$ npm install
cf-sample-app-nodejs@0.0.0 /.../cf-sample-app-nodejs
├─┬ body-parser@1.15.0
│ ├── bytes@2.2.0
│ ├── content-type@1.0.1

...
</pre>

Once dependencies are installed, you will be ready to run your app locally.

Upon running `cf push`, we will also push our whole dependencies folder `node_modules`. Since Cloud Foundry runs `npm install` anyways, this is redundant and should be omitted to save bandwidth and even more importantly: time. You can create a `.cfignore` file which works just like a `.gitignore` file and which tells Cloud Foundry what files should be excluded when pushing. Let's create a `.cfignore` file and exclude the `node_modules` folder:

```txt
node_modules
```

<p class="note">
  <strong>Pro Tip</strong>: To lock down your dependencies' versions before pushing, you can run <code>npm shrinkwrap</code>. This will create a <code>npm-shrinkwrap.json</code> file which holds the exact versions of all your dependencies. Any <code>npm install</code> will then install exactly these versions so you can be sure that your app is using versions which work.
</p>

<div style="text-align:center;margin:3em;">
  <a href="./run-locally.html" class="btn btn-primary">I've installed the App dependencies locally</a>
</div>