Nginx autoindex only with specific URI argument?

Question

This is a bit hard to describe. I basically want nginx to respond with the autoindex instead of the set index.html file, if there's ?listing=true in the URI.

I already tried having this inside my location / {...}, to make it not have any index to show:

if ($arg_listing = "true") { index =404; add_header Content-Type application/json; return 200; } 

But that made the nginx service not start, because apparently you cannot have index or autoindex inside an if block. I know that the if block works at least, because the 200 is returned if I remove the index.

I'm not that experienced in using nginx, so I have no idea what I should do. Here's the full /etc/nginx/sites-enabled/default configuration: https://pastebin.com/iRiMpCk9

Edit: Changed the Pastebin link, because it was the wrong one before.

Answer 1

Actually, an if nginx directive, when being used in location context, has a very little in common with similar constructions from imperative programming languages. One of the best explanations of how this directive actually works was provided by Yichun Zhang, the author of the famous lua-nginx-module and the OpenResty bundle. In fact, every if directive implicitly creates a nested location that tries to inherit all the declarations from the parent location. There are, however, certain limitations on which directives can be used in the so-called "if in location" context (if they can, it will be explicitly stated in documentation), and you have just encountered one of them (the autoindex directive cannot be used in this context). The most common solution to such situations is to use variables as arguments for these directives.

Unfortunately, not all nginx directives allow the use of variables as their parameters (as a rule, if this is possible, it is explicitly stated in the documentation for the corresponding directive). In particular, the autoindex directive does not support specifying its parameter as a variable whose value could be either on or off. Therefore, indeed, the solution involving the use of two separate named locations with different configurations for this directive is most likely the only possible option. However, as I already said, you can't jump to the named location via rewrite directive. Instead, you can do it via the try_files directive, as described here:

map $arg_listing $autoindex { true @autoindex_on; default @autoindex_off; } server { ... listen, server_name, root and other common "server" block parameters here location / { try_files "" $autoindex; } location @autoindex_on { autoindex on; autoindex_format json; } location @autoindex_off { return 403; } ... your other locations here } 

But keep in mind, that in order for autoindex directive to take effect, there must not be an index file (index.html by default) in the requested web server directory.

Answer 2

try this:

server { listen 80; server_name example.com; root /var/www/html; # Default behavior: Serve files or the index.html location / { try_files $uri $uri/ /index.html; } # Named location for autoindex location @listing { autoindex on; autoindex_exact_size off; # Optional: Makes file sizes human-readable autoindex_localtime on; # Optional: Displays local times for files } # Rewrite based on the presence of the query parameter location / { if ($arg_listing = "true") { rewrite ^ /@listing last; } try_files $uri $uri/ /index.html; } }