.Net Core / IIS web config rewrite rules

Question

In my situation I have two domains:

domain.com
domain1.com

where domain1.com is the alias of domain.com

For domain1.com I want to allow only traffic for the urls starting with api/ and redirect all other traffic to domain.com with 301 status code.

i.e. I want to allow requests like domain1.com/api/products/list on the other hand I want to redirect domain1.com/products/list to domain.com

Can anyone please guide how to achieve this with web.config?

Answer 1

Following URL redirect rule should work.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="Domain1">
                    <match url="^(.+)" />
                    <conditions>
                        <add input="{HTTP_URL}" pattern="^/api/(.+)" negate="true" /> 
                    </conditions>
                    <action type="Redirect" url="http://domain/{R:1}" redirectType="Permanent" appendQueryString="true" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

Quick explanation.

• We capture the whole incoming URL with match pattern for back-reference for the redirect if needed.
• And in conditions we negate the API URLs pattern, hence the rule is applied to the URLs not containing /api.
• The redirect action takes the captured back-reference and appends it to the domain.

Notes.

• You might need to adjust slashes in the rule, I assume there will always be a slash after /api.
• Browsers heavily cache permanent redirects, make sure to use a new Incognito/Private session each time you modify the rule.