Polymer + Firebase Makefile


I’m at the Polymer Summit in London today, and finally writing up a build process for Polymer apps hosted on Firebase that I’m satisfied with enough to recommend.

The problem is this: if you create an app using web components installed with Bower, and import each component using <link rel="import" href="bower_components/component-name/component-name.html">, the bower_components folder will be inside your app folder.

This is fine for development, but when you deploy the app to a remote server (e.g. Firebase), you don’t want all the files in the bower_components folder to be deployed to the public server as part of your app - not only does it take much longer to upload, but there could be security problems with demo files hiding in any of the component folders.

So you need a build process, which builds the public app in a build folder and deploys that folder instead, without the `bower_components` folder.

The Makefile for this build process is quite straightforward:

.PHONY: clean lint build deploy serve

all: build

    rm -rf build

    #   node_modules/polylint/bin/polylint.js

build: clean lint
    cp -r app build
    node_modules/vulcanize/bin/vulcanize --inline-scripts --inline-css app/elements.html -o build/elements.html

deploy: build
    firebase deploy --public build

    firebase serve

Running make build builds the app: first making a copy of the app folder called build, then running vulcanize on app/elements.html (which includes all the <link rel="import" href="…"> imports) to create a single build/elements.html file containing all the imported code. It inlines all the script and style dependencies of those components, so everything is imported from build/elements.html instead of individual files in bower_components.

There are a few more things the build process can/could do: lint the app using polylint (currently disabled as it finds too many errors in third-party components) and lint the JavaScript using standard. It could also run crisper to move all the inline JS and CSS into separate files, but I haven’t done that here.

Running make deploy runs firebase deploy, setting build as the public folder. The “ignore” setting in the firebase.json file (see below) tells it not to upload anything in bower_components, so in the end only a few files are uploaded and deployed.

  "hosting": {
    "public": "app",
    "ignore": [
    "rewrites": [ {
      "source": "**",
      "destination": "/index.html"
    } ]

index.html is untouched, leaving it readable as a manifest and allowing it to be loaded and parsed quickly.