Question

I’m working on a website that uses IIS 7’s URL rewriting feature to do a permanent redirect from example.com to http://www.example.com, as well as rewrites from similar domain names to the “main” one, such as from http://www.examples.com to http://www.example.com.

This rewrite rule – shown below – has worked well for some time now. However, we recently added HTTPS support and noticed that if users visit one of the URLs to be rewritten to http://www.example.com then HTTPS is dropped. For instance, if a user visits https://example.com they get redirected to http://www.example.com, whereas we would like them to be sent to https://www.example.com.

Here is the rewrite rule of interest (in Web.config):

<rule name="Canonical Host Name" stopProcessing="true">
    <match url="(.*)" />

    <conditions logicalGrouping="MatchAny">
        <add input="{HTTP_HOST}" pattern="^example\.com$" />
        <add input="{HTTP_HOST}" pattern="^(www\.)?example\.net$" />
        <add input="{HTTP_HOST}" pattern="^(www\.)?example\.info$" />
        <add input="{HTTP_HOST}" pattern="^(www\.)?examples\.com$" />
    </conditions>

    <action type="Redirect" url="http://www.example.com/{R:1}" redirectType="Permanent" />
</rule>

As you can see, the action element’s url attribute points directly to http://, so I get why https://example.com is redirected to http://www.example.com. My question is, how do I fix this? I tried (naively) to just drop the http:// part from the url attribute, but that didn’t work.

Answer 1

Figured out the answer with some help from my colleagues.

I needed to use multiple rules with a condition on {HTTPS}. Note the {HTTPS} condition in the rules below.

<rule name="Canonical Host Name (HTTP)" stopProcessing="true">
    <match url="(.*)" />

    <conditions logicalGrouping="MatchAny">
        <add input="{HTTPS}" pattern="OFF" />
        <add input="{HTTP_HOST}" pattern="^example\.com$" />
    </conditions>

    <action type="Redirect" url="http://www.example.com/{R:1}" redirectType="Permanent" />
</rule>

<rule name="Canonical Host Name (HTTPS)" stopProcessing="true">
    <match url="(.*)" />

    <conditions logicalGrouping="MatchAny">
        <add input="{HTTPS}" pattern="ON" />
        <add input="{HTTP_HOST}" pattern="^example\.com$" />
    </conditions>

    <action type="Redirect" url="https://www.example.com/{R:1}" redirectType="Permanent" />
</rule>

I then repeated the rule pair above for the alternate domain names.