Step 4. Deploy - Polymer Project

In this step, you'll deploy your application to the web.

Build for deployment

Run the following Polymer CLI command to perform a number of steps to prepare your application for deployment:

polymer build

This command minifies the HTML, JS, and CSS dependencies of your application, and generates a service worker that precaches all of the dependencies of your application so that it can work offline.

The built files are output to the following folders:

build/unbundled. Contains granular resources suitable for serving via HTTP/2 with server push.
build/bundled. Contains bundled (concatenated) resources suitable for serving from servers or to clients that do not support HTTP/2 server push.

Deploy to a server

Polymer applications can be deployed to any web server.

This template utilizes the <app-location> element to enable URL-based routing, which requires that the server serve the index.html entry point for all routes.

You can follow one of the sections below to deploy this app to either Google AppEngine or Firebase Static Hosting, which are both free and secure approaches for deploying a Polymer app. The approach is similar for other hosting providers.

Deploy with AppEngine

Download the Google App Engine SDK and follow the instructions for your platform to install it.
Sign up for an AppEngine account.
Open the project dashboard and create a new project
- Click the Create Project button.
- Type a project name.
- Click the Create button.
cd into your project directory.

Create an app.yaml file and instruct the server to serve up index.html for any URL's that don't otherwise end in a file extension. Replace {project name} with the name you chose in the previous step.

application: {project name}
version: 1
runtime: python27
api_version: 1
threadsafe: yes

handlers:
- url: /bower_components
  static_dir: build/bundled/bower_components
  secure: always

- url: /images
  static_dir: build/bundled/images
  secure: always

- url: /src
  static_dir: build/bundled/src
  secure: always

- url: /service-worker.js
  static_files: build/bundled/service-worker.js
  upload: build/bundled/service-worker.js
  secure: always

- url: /manifest.json
  static_files: build/bundled/manifest.json
  upload: build/bundled/manifest.json
  secure: always

- url: /.*
  static_files: build/bundled/index.html
  upload: build/bundled/index.html
  secure: always

Deploy.

appcfg.py -A {project name} update app.yaml

Deploy with Firebase

The instructions below are based on the Firebase hosting quick start guide.

Sign up for a Firebase account.
Install the Firebase command line tools.
```
npm install -g firebase-tools
```
The -g flag instructs npm to install the package globally so that you can use the firebase command from any directory. You may need to install the package with sudo privileges.
cd into your project directory.
Inititalize the Firebase application.
```
firebase login
firebase init
```
Firebase asks you which app you would like to use for hosting. If you just signed up, you should see one app with a randomly-generated name. You can use that one. Otherwise go to https://www.firebase.com/account to create a new app.
Firebase asks you the name of your app's public directory. Enter build/bundled. This works because when you run polymer build to build your application, Polymer CLI places your bundled application appropriate for serving on Firebase into the build/bundled folder.
Edit your firebase configuration to add support for URL routing. The final firebase.json file should look something like this:
```
{
  "hosting": {
    "public": "build/bundled/",
    "rewrites": [
      {
        "source": "**/!(*.*)",
        "destination": "/index.html"
      }
    ]
  }
}
```
This instructs Firebase to serve up index.html for any URLs that don't otherwise end in a file extension.
Deploy.
```
firebase deploy
```
The URL to your live site is listed in the output.