How can I prevent error when subdomain does not exist?

Question

Every subdomain is in a separate folder. I capture the subdomain and set the root to the correct folder with this code:

server_name ~^(?<sub>.+)\.mysite\.com$;
root "/path/to/my/site/$sub";

When the sub domain does not exist, it throws a 404 error, but not using my 404 error page because the root is set to a directory that does not exist.

I can solve the problem with this code:

server_name ~^(?<sub>.+)\.mysite\.com$;
if (!-d "/path/to/my/site/$sub") {
    set $sub www;
    #set $sub "";
}
root "/path/to/my/site/$sub";

but obviously, it is wrong because if is evil, or have I found an exception where it is correct of me to use if.

Why do you need to do it in the same `server` block? Use a catch-all `server` block. See [this answer](https://serverfault.com/questions/783346/prevent-default-server-or-wildcard-in-nginx/783375#783375), but make the response anything you like. — Richard Smith, Apr 22 '18 at 11:23
@MichaelHampton I have tried with `error_page` and it doesn't work. It only works if the error page is static, and it needs to be a `.php` file. — Dan Bray, Apr 22 '18 at 20:00

score 0 · Answer 1 · answered Apr 23 '18 at 23:18

There was a problem with the code for my error page. That now works, which has allowed me to fix a different problem (extensionless php with redirects).

error_page 404 =200 /404.php;    
location = /404 {
    #root "/path/to/404/page";
}

I tried setting the root inside location = /404 but that does not work. I have found no way to avoid the if statement and still make it work correctly.

if (!-d "/path/to/my/site/$sub") {
    return 301 https://www.example.com$request_uri;
}

I guess it's better to have a very small amount of if statements for redirects, than to have a broken website.

Even Plesk Onyx's auto generated code used an if statement:

if ($host ~* ^example\.com$) {
    return 301 https://www.$host$request_uri;
}

However, I would still prefer to avoid if statements altogether, if i can get my site to work 100% correctly without them.

How can I prevent error when subdomain does not exist?

1 Answers1