IIS Reverse Proxy Apply outbound rule on specific path - iis

Question

I have the following inbound and outbound rules defined to get my reverse proxy working.
<rewrite>
<rules>
<rule name="Route the requests for backend app" stopProcessing="true">
<match url="^foldera/folderb/(.*)" />
<conditions>
<add input="{HTTP_HOST}" pattern="www.site1.com" />
</conditions>
<action type="Rewrite" url="http://www.site2.com/{R:1}" />
<serverVariables>
<set name="HTTP_ACCEPT_ENCODING" value="" />
</serverVariables>
</rule>
</rules>
<outboundRules>
<rule name="RewriteRelativePaths" preCondition="ResponseIsHtml" enabled="true" stopProcessing="false">
<match filterByTags="A, Area, Base, Form, Frame, Head, IFrame, Img, Input, Link, Script" pattern="^/(.*)" />
<action type="Rewrite" value="/foldera/folderb/{R:1}" />
<conditions>
<add input="{URL}" pattern="^/foldera/folderb/.*" />
</conditions>
</rule>
<preConditions>
<preCondition name="ResponseIsHtml">
<add input="{RESPONSE_CONTENT_TYPE}" pattern="^text/html" />
</preCondition>
</preConditions>
</outboundRules>
</rewrite>
Now, the site "http://www.site2.com/" is correclty loaded in "http://www.site1.com/foldera/folderb/" and the outbound rule is making sure that every resource from site2 is rewritten to http://www.site1.com/foldera/folderb/{resourcefromsite1}
Unfortunately, the outbound rule is also crashing the rest of my site. Probably because he's trying to rewrite every native resource to this same "http://www.site1.com/foldera/folderb/" folderstructure.
How can I make the outbound rule only to respond to resources that are requested/loaded through path http://www.site1.com/foldera/folderb/ and for instance not through http://www.site1.com/foldera
Cheers
Jeroen

Answer 1

You were very close to solution. To solve this you must add {URL} as input inside your preCondition. Your rewrite rules should look like this finally:
<rewrite>
<rules>
<rule name="Route the requests for backend app" stopProcessing="true">
<match url="^foldera/folderb/(.*)" />
<conditions>
<add input="{HTTP_HOST}" pattern="www.site1.com" />
</conditions>
<action type="Rewrite" url="http://www.site2.com/{R:1}" />
<serverVariables>
<set name="HTTP_ACCEPT_ENCODING" value="" />
</serverVariables>
</rule>
</rules>
<outboundRules>
<rule name="RewriteRelativePaths" preCondition="ResponseIsHtml" enabled="true" stopProcessing="false">
<match filterByTags="A, Area, Base, Form, Frame, Head, IFrame, Img, Input, Link, Script" pattern="^/(.*)" />
<action type="Rewrite" value="/foldera/folderb/{R:1}" />
<!-- Removed condition from here -->
</rule>
<preConditions>
<preCondition name="ResponseIsHtml">
<add input="{RESPONSE_CONTENT_TYPE}" pattern="^text/html" />
<add input="{URL}" pattern="^/foldera/folderb/.*" /> <!-- Added your condition here -->
</preCondition>
</preConditions>
</outboundRules>
</rewrite>
This way Outbound Rule will be applied only when Response is HTML and current URL got specified pattern.