Rewrite image request to sub-directory structure in Nginx

Question

Given a location like this:

location ~ ^/user-content/img/) {
  root /srv/foo/bar/uploads/;
  autoindex off;
  access_log off;
  expires 30d;
}

Is it possible using nginx to have a request for

/user-content/img/3AF1D3A69CE92ADAED8B0D25C2411595C7C798A5.png

To be actually served from directory /srv/foo/bar/uploads/3A/F1/D3 which would involve taking the first two characters from the request filename and use them as first subfolder, then using characters 3-4 for the next deeper folder and finally append characters 5-6 for the last subfolder?

Just FYI, approach proposed by me works as well. Didn't understand first time that you need to preserve the full filename after the path forming of three subfolders. — Ivan Shatsky, Oct 23 '20 at 11:39
@IvanShatsky Well then I'll have to try it again. Didn't work the first time I tried it. — Oliver Weichhold, Oct 23 '20 at 13:31
That's because I didn't understand the question correctly and instead of `/srv/foo/bar/uploads/3A/F1/D3/3AF1D3A69CE92ADAED8B0D25C2411595C7C798A5.png` the first version was checking for `/srv/foo/bar/uploads/3A/F1/D3/A69CE92ADAED8B0D25C2411595C7C798A5.png` (trimming first 6 characters from filename). — Ivan Shatsky, Oct 23 '20 at 13:39

Ivan Shatsky · Accepted Answer · 2020-10-23T11:34:05.743

1

You can try (not tested)

location /user-content/img/ {
    rewrite "^/user-content/img/(\w{2})(\w{2})(\w{2})(.*)" /$1/$2/$3/$1$2$3$4 break;
    root /srv/foo/bar/uploads;
    autoindex off;
    access_log off;
    expires 30d;
}

Update

Just give it a test. Can confirm that this approach works too. As OP noted, regex with curly braces should be quoted in nginx config.

edited Oct 23 '20 at 11:34

answered Oct 22 '20 at 18:50

Ivan Shatsky

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Confirmed working and actually more elegant. – Oliver Weichhold Oct 23 '20 at 13:39

Tero Kilkanen · Answer 2 · 2020-10-23T21:09:13.217

1

This approach should work:

location ~ "^/user-content/img/([0-9A-F]{2})([0-9A-F]{2})([0-9A-F]{2})(.*)$" {
    root /srv/foo/bar/uploads;
    try_files /$1/$2/$3/$1$2$3$4 =404;
    autoindex off;
    access_log off;
    expires 30d;
}

In the location line, we capture parts of the filename to four different variables using regular expressions, first three parts being the directory and fourth part being the rest of the filename.

Variables are used in the try_files directive to create the path to the image name.

edited Oct 23 '20 at 21:09

answered Oct 22 '20 at 19:17

Tero Kilkanen

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Very cool. Thanks. – Oliver Weichhold Oct 22 '20 at 21:00
2

By the way. I had to quote the regex in the first line due to the use of curly braces. Perhaps you want to correct that in your answer. – Oliver Weichhold Oct 22 '20 at 22:14
Thanks! I use curly braces in my nginx regexes so rarely that I forget it... – Tero Kilkanen Oct 23 '20 at 21:09

Rewrite image request to sub-directory structure in Nginx

2 Answers2