SEO – Is your Azure WebSites hosted AngularJS App ready for Google :-)

Every AngularJS application is just a website which is generated by executing javascript. The google crawler and also other crawlers are not able to collect information from these sites. To handle this problem a couple of services like AjaxSnapshots or Prerender.io are trying to fill the gap. Basically these services are generating a snapshot of a website without any javascript in it. Whenever the search engine visits the page, the system delivers a plain html page without any javascript. Many technical details on how search engines crawl a page can be found here. Users who are hosting on Azure WebSites and trying to use this kind of pre-rendering tools may stuck with some configuration issues.

The required rewrite rules for the web.conf are written very fast or can be found in the AjaxSnapshots documentation:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="AjaxSnapshotsProxy" stopProcessing="true">
                    <!-- test all requests -->
                    <match url="(.*)" />
                    <conditions trackAllCaptures="true">
                        <!-- only proxy requests with an _escaped_fragment_ query parameter -->
                        <add input="{QUERY_STRING}" pattern="(.*_escaped_fragment_=.*)" />
                        <!-- used to capture the scheme/protocol for use in the rewrite below --> 
                        <add input="{CACHE_URL}" pattern="^(https?://)" />
                    </conditions>
                    <!-- send the request to the AjaxSnapshots service -->
                    <action type="Rewrite" 
                    url="http://api.ajaxsnapshots.com/makeSnapshot?url={UrlEncode:{C:2}{HTTP_HOST}:{SERVER_PORT}{UNENCODED_URL}}&amp;apikey=<YOUR API KEY>" 
                    logRewrittenUrl="true" appendQueryString="false" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

An example for Prerender.io can be found here.

After applying the web.conf to the website, the browser returns directly a 404 which means that the website behind the target URI is wrong. This is because Azure Websites enabled the redirect module but rewriting URLs to external target requires a revers proxy module additionally. This module which is part of the application request routing in IIS is not activated in Azure WebSites by default. Thanks to the following nice trick it’s possible to use the reverse proxy module also in Azure WebSites:

http://ruslany.net/2014/05/using-azure-web-site-as-a-reverse-proxy/

As usual all technical frameworks, components or services described in this blog are used in production for several weeks in different applications, e.g. the Azure Cost Monitor. These steps should help to get every AngularJS application ready for google and other bots when the site is hosted on Azure WebSites.

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