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alancc
Asked: 2023-09-13 00:27:11 +0800 CST

How to disable .htaccess redirect for a specific folder

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I write the following .htaccess rules to redirect all URLs from www.a.com to www.b.com:

RewriteEngine on
RewriteCond %{http_host} ^www.a.com [NC,OR]
RewriteCond %{http_host} ^a.com [NC]
RewriteRule ^(.*)$ https://www.b.com/myfolder/ [R=301,NC,L]

Now there is a file under a subdir of a.com, as below:

www.a.com/.well-known/acme-challenge/#######

It is used for AutoSSL renewal. With the above redirection, the AutoSSL will not be able to find the file any more, so fail the renewal.

So, is it possible to disable the redirect under /.well-known/acme-challenge/?

.htaccess

1 Answers

  1. Best Answer

    Since you are redirecting everything to a fixed URL-path you might as well build the exception directly in the RewriteRule directive (there is no need to capture the URL-path as you are currently doing).

    For example:

    RewriteCond %{HTTP_HOST} ^(www\.)?a\.com [NC]
RewriteRule !^\.well-known/acme-challenge/ https://www.b.com/myfolder/ [R=301,L]

    The ! prefix on the RewriteRule pattern negates the expression, so it is successful when the regex does not match. In this case when the requested URL-path does not start .well-known/acme-challenge/. (However, see the "edge case" below.)

    I also combined your two conditions (RewriteCond directives) into one. There is no need for the NC flag on the rule itself (assuming you are on Linux, not Windows).

    Remember to backslash-escape literal dots in the regex.

    Edge case (Optional extra)

    Note that if you also have a front-controller pattern later in the .htaccess file (eg. WordPress, Joomla, most other frameworks/CMS, etc.) then you should also add a condition to the above rule to prevent rewrites to the front-controller being redirected when requesting a URL of the form /.well-known/acme-challenge/<non-existent-file>. For example:

    RewriteCond %{ENV:REDIRECT_STATUS} ^$
:

    Without this condition then a request for http://a.com/.well-known/acme-challenge/<non-existent-file> would otherwise be redirected to https://www.b.com/index.php (assuming index.php is the front-controller).

    Summary

    The complete rule would then become:

    RewriteEngine On

RewriteCond %{ENV:REDIRECT_STATUS} ^$
RewriteCond %{HTTP_HOST} ^(www\.)?a\.com [NC]
RewriteRule !^\.well-known/acme-challenge/ https://www.b.com/myfolder/ [R=301,L]

# Front-controller pattern follows...

    UPDATE:

    if the redirect is a simple line: redirect 301 / https://www.b.com/myfolder/, how to write the exception for /.well-known/acme-challenge/?

    Since the simple Redirect (mod_alias) directive itself does not provide the ability to make "exceptions", you would need to surround the directive in an <If> expression (requires Apache 2.4). For example:

    <If "%{REQUEST_URI} !~ m#^/\.well-known/acme-challenge/#">
    Redirect 301 / https://www.b.com/myfolder/
</If>

    Reference: https://httpd.apache.org/docs/2.4/expr.html

    (If you are using the Redirect directive like this then there is no "front-controller" pattern and no "edge case" as mentioned above.)

    Aside: Whilst they might look similar, this Redirect directive is quite different to the RewriteRule directive used earlier and produces different results. The RewriteRule directive above discards the requested URL-path, redirecting everything to https://www.b.com/myfolder/. However, the Redirect directive used here preserves the requested URL-path, prefixing the URL-path with /myfolder (eg. /foo/bar is redirected to https://www.b.com/myfolder/foo/bar)

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