An example of using server-side Go templating to serve a multi-tenanted Polymer client using AppEngine. Each client could be served from it's own custom domain or using a CNAME from a root service (e.g. tenant.service.com).

Examples:

• https://red-dot-go-poly-tenant.appspot.com/
• https://green-dot-go-poly-tenant.appspot.com/
• https://blue-dot-go-poly-tenant.appspot.com/

The dummy tenants are generated via the /app/warmup.go file.

Yes, those are some funky URLs, the '-dot-' part is todo with how AppEngine provides HTTPS for appspot.com domains. In reality you'd use a custom domain so you would have tenant URLs like red.myservice.com or www.red.com.

The index.html page and manifest.json file is generated dynamically for the domain it's being served from. All other static files are served by the AppEngine frontend edge cache (like a CDN).

Creating the index.html page from a template saves having to download the app and then make a separate request to get the runtime config for the tenant. We want fast and zippy and no waiting to render. This could also be used to add additional server-side meta-data for SEO, open-graph etc... by adding a little more server-side routing to the mix.

The app config and tenant data (for use within the app) is set to the MyApp global object. It can contain additional config settings such as api, auth or image endpoints.

You need to have

• Go SDK for AppEngine
• Polymer CLI

The /app folder contains the AppEngine application and also serves the polymer frontend SPA from a static folder which uses a symlink to point to the regular Polymer-CLI build folder. Create it in the /app folder using:

$ ln -s ../build/unbundled static

Build the polymer app using ./build.sh. This runs polymer build with the parameters to include the additonal files required (images and the webcomponent polyfill).

Start the app locally by running goapp serve within the /app folder

Go to one of the tenant sites:

• http://red.127.0.0.1.xip.io:8080/
• http://green.127.0.0.1.xip.io:8080/
• http://blue.127.0.0.1.xip.io:8080/

xip.io is a wildcard DNS service that can be used when developing locally.

I normally have the root index.html page set to use a dev tenant configuration.