Nginx -- static file serving confusion with root & alias
Just a quick addendum to @good_computer's very helpful answer, I wanted to replace to root of the URL with a folder, but only if it matched a subfolder containing static files (which I wanted to retain as part of the path).
For example if file requested is in /app/js
or /app/css
, look in /app/location/public/[that folder]
.
I got this to work using a regex.
location ~ ^/app/((images/|stylesheets/|javascripts/).*)$ {
alias /home/user/sites/app/public/$1;
access_log off;
expires max;
}
There is a very important difference between the root
and the alias
directives. This difference exists in the way the path specified in the root
or the alias
is processed.
root
- the
location
part is appended toroot
part - final path =
root
+location
alias
- the
location
part is replaced by thealias
part - final path =
alias
To illustrate:
Let's say we have the config
location /static/ {
root /var/www/app/static/;
autoindex off;
}
In this case the final path that Nginx will derive will be
/var/www/app/static/static
This is going to return 404
since there is no static/
within static/
This is because the location part is appended to the path specified in the root
. Hence, with root
, the correct way is
location /static/ {
root /var/www/app/;
autoindex off;
}
On the other hand, with alias
, the location part gets dropped. So for the config
location /static/ {
alias /var/www/app/static/;
autoindex off; ↑
} |
pay attention to this trailing slash
the final path will correctly be formed as
/var/www/app/static
In a way this makes sense. The alias
just lets you define a new path to represent an existing "real" path. The location part is that new path, and so it gets replaced with the real path. Think of it as a symlink.
Root, on the other hand is not a new path, it contains some information that has to be collated with some other info to make the final path. And so, the location part is used, not dropped.
The case for trailing slash in alias
There is no definitive guideline about whether a trailing slash is mandatory per Nginx documentation, but a common observation by people here and elsewhere seems to indicate that it is.
A few more places have discussed this, not conclusively though.
https://serverfault.com/questions/376162/how-can-i-create-a-location-in-nginx-that-works-with-and-without-a-trailing-slas
https://serverfault.com/questions/375602/why-is-my-nginx-alias-not-working
In your case, you can use root
directive, because $uri
part of the location
directive is the same with last root
directive part.
Nginx documentation advices it as well:
When location matches the last part of the directive’s value:location /images/ { alias /data/w3/images/; }
it is better to use the root directive instead:
location /images/ { root /data/w3; }
and root
directive will append $uri
to the path.
as say as @treecoder
In case of the
root
directive, full path is appended to the root including the location part, whereas in case of thealias
directive, only the portion of the path NOT including the location part is appended to the alias.
A picture is worth a thousand words
for root
:
for alias
: