Can an htpasswd apply to all URLs except one? - apache

Question

I have an htaccess setup for my domain, but I want one specific URL to not have htpasswd protection. That URL is a rewritten URL and doesn't have an actual directory associated with it.
Is there a way to use the root htaccess to htpasswd protect the entire site except for that one specific URL?
Edit (my code, including Jon Lin's suggestion, which isn't working for me):
RewriteCond %{SERVER_NAME} =subdomain.example.com
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php/$1 [L]
SetEnvIf Request_URI "^/messenger/parse" NOPASSWD=true
AuthUserFile /xxx/xxx/xxx/xxxxxx/subdomain.example.com/.htpasswd
AuthName "Staging Server"
AuthType Basic
Order Deny,Allow
Satisfy any
Deny from all
Require valid-user
Allow from env=NOPASSWD

Answer 1

You can setup something like SetEnvIf to set an environment variable for a given Request URI. Then in the auth definition, you can use the Satisfy Any and Allow from env directives to tell apache that access can be granted either by authentication or if the environment variable exists (which is only set for a specific URI). Example:
# set the NOPASSWD variable if the request is for a specific URI
SetEnvIf Request_URI "^/specific/uri/nopasswd/$" NOPASSWD=true
# Auth directives
AuthUserFile /var/www/htpasswd
AuthName "Password Protected"
AuthType Basic
Order Deny,Allow
# Any requirment satisfies
Satisfy any
# Deny all requests
Deny from all
# except if user is authenticated
Require valid-user
# or if NOPASSWD is set
Allow from env=NOPASSWD