Reverse proxy responding with 404 error and response URL incorrect when error

Question

I have a site1 which is a web client application. site1 calls some site2 APIs which is running into CORS issue.

I have written rewrite rules in IIS to rewrite the request matching string extFlow in the URL.

From https://site1/xyz/extFlow/Test.svc/testAPI to https://site2/extFlow/Test.svc/testAPI

Following is my rewrite rule. The response seems to be written back to https://site1/extFlow/Test.svc/testAPI and not https://site1/xyz/extFlow/Test.svc/testAPI. If site2 responds with 500, the final response from IIS reverse proxy is 404.

<rewrite> 
        <rules> 
            <rule name="Route the requests for WFL" stopProcessing="true"> 
                <match url="extFlow/(.*)" /> 
                <conditions> 
                </conditions> 
                <action type="Rewrite" url="https://site2/extFlow/{R:1}" logRewrittenUrl="true" />
                <serverVariables>
                    <set name="HTTP_X_ORIGINAL_ACCEPT_ENCODING" value="{HTTP_ACCEPT_ENCODING}" />
                    <set name="HTTP_ACCEPT_ENCODING" value="" />
                </serverVariables> 
        </rules> 
        <outboundRules> 
            <rule name="ReverseProxyOutboundRule1" preCondition="NeedsResportingAcceptResp" stopProcessing="true"> 
                <match filterByTags="A" serverVariable="HTTP_ACCEPT_ENCODING" pattern="^(.*)" /> 
                <action type="Rewrite" value="{HTTP_X_ORIGINAL_ACCEPT_ENCODING}" /> 
            </rule> 
            <preConditions> 
                <preCondition name="NeedsResportingAcceptResp">
                    <add input="{HTTP_X_ORIGINAL_ACCEPT_ENCODING}" pattern=".+" />
                </preCondition> 
            </preConditions> 
        </outboundRules> 
</rewrite>  

<handlers>
        <remove name="svc-ISAPI-4.0_64bit" />
        <remove name="svc-ISAPI-4.0_32bit" />
        <remove name="svc-Integrated-4.0" />
</handlers>

gouigoui gouigoui · Accepted Answer · 2018-03-07T13:23:34

Maybe is an outbound rule missing?

<rule name="ReverseProxyOutboundRule1" preCondition="ResponseIsHtml1"> 
    <match filterByTags="None" pattern="^https://site2/extFlow($|/(.*))" /> 
    <action type="Rewrite" value="https://site1/xyz/extFlow/{R:2}" /> 
 </rule>

Reverse proxy responding with 404 error and response URL incorrect when error

1 Answers