Nginx: Difference between revisions

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Nginx [engine x] is an HTTP and reverse proxy server, as well as a mail proxy server, written by Igor Sysoev. The nginx project started with a strong focus on high concurrency, high performance and low memory usage. It is licensed under the 2-clause BSD-like license and it runs on Linux, BSD variants, Mac OS X, Solaris, AIX, HP-UX, as well as on other *nix flavours. It also has a proof of concept port for Microsoft Windows.

The following is community-contributed documentation on Nginx configuration. Amendments and additions are welcome.

Nginx configuration

PHP-FPM

Nginx is usually configured to interface with PHP via php-fpm. This is both fast and robust.

PHP-FPM's default behaviour for pools is usually to restrict the execution of scripts to a specific extension, i.e. .php. You should ensure that this behaviour is configured within your particular package/distribution, e.g. for debian,

/etc/php/7.4/fpm/pool.d/www.conf

security.limit_extensions = .php

Nginx

Add the following 'slash arguments' compatible 'location' block to your vhosts 'server' in your nginx configuration (further explanation at 'Using slash arguments').

nginx.conf location:

location ~ [^/]\.php(/|$) {
    fastcgi_split_path_info  ^(.+\.php)(/.+)$;
    fastcgi_index            index.php;
    fastcgi_pass             127.0.0.1:9000 (or your php-fpm socket);
    include                  fastcgi_params;
    fastcgi_param   PATH_INFO       $fastcgi_path_info;
    fastcgi_param   SCRIPT_FILENAME $document_root$fastcgi_script_name;
}

If the above does not work try the following: Note: This was for CentOS 7.6 (1804), MariaDB 10.3, Nginx 1.15 and PHP 7.3.5

location ~ ^(.+\.php)(.*)$ {
    root /usr/share/nginx/html/moodle/;
    fastcgi_split_path_info  ^(.+\.php)(.*)$;
    fastcgi_index            index.php;
    fastcgi_pass             127.0.0.1:9000;
    include /etc/nginx/mime.types;
    include                  fastcgi_params;
    fastcgi_param   PATH_INFO       $fastcgi_path_info;
    fastcgi_param   SCRIPT_FILENAME $document_root$fastcgi_script_name;
}

If you find that this does not work (scripts, styles, and images not loading) and that there are open() "..." failed (20: Not a directory) lines appearing in your logs: Check whether there are any directives related to static content before this block and try moving them after this block.

Another potential pitfall is the use of try_files. Many guides recommend configurations like

try_files $fastcgi_script_name =404;

. But if try_files is used, nginx deletes the content of the $fastcgi_path_info variable (this is intended behavior). This causes PATH_INFO to also be empty, so slash arguments don't work. An alternative is the use of

if(!-f $document_root$fastcgi_script_name) {return 404;}

as recommended by the nginx documentation, although the nginx documentation also recommends not using if.

Error pages

# This passes 404 pages to Moodle so they can be themed
error_page 404 /error/index.php;    error_page 403 =404 /error/index.php;

Hiding internal files

# Hide all dot files but allow "Well-Known URIs" as per RFC 5785
location ~ /\.(?!well-known).* {
    return 404;
}
 
# This should be after the php fpm rule and very close to the last nginx ruleset.
# Don't allow direct access to various internal files. See MDL-69333
location ~ (/vendor/|/node_modules/|composer\.json|/readme|/README|readme\.txt|/upgrade\.txt|db/install\.xml|/fixtures/|/behat/|phpunit\.xml|\.lock|environment\.xml) {
    deny all;
    return 404;
}

XSendfile aka X-Accel-Redirect

Setting Moodle and Nginx to use XSendfile functionality is a big win as it frees PHP from delivering files allowing Nginx to do what it does best, i.e. deliver files.

Enable xsendfile for Nginx in Moodles config.php, this is documented in the config-dist.php, a minimal configuration look like this,

$CFG->xsendfile = 'X-Accel-Redirect';
$CFG->xsendfilealiases = array(
    '/dataroot/' => $CFG->dataroot
);

Accompany this with a matching 'location' block in your nginx server configuration.

location /dataroot/ {
    internal;
    alias <full_moodledata_path>; # ensure the path ends with /
}

The definition of 'internal' here is critical as it prevents client access to your dataroot.

Load Balancer Hints (AWS)

If you're using an AWS load balancer in front your infrastructure, you can set up some of the configuration above, preventing traffic to go forward. Here is the configuration applied to hide files, with a few considerations due to known limitations:

100 total rules per application load balancer
5 condition values per rule
5 wildcards per rule
5 weighted target groups per rule:

[
    {
        "Conditions": [
            {
                "Field": "path-pattern", 
                "Values": [
                    "*/.*", 
                    "*/upgrade.txt", 
                    "*/db/install.xml",
                    "*/README.md"
                ], 
                "PathPatternConfig": {
                    "Values": [
                        "*/.*", 
                        "*/upgrade.txt", 
                        "*/db/install.xml",
                        "*/README.md"
                    ]
                }
            }
        ], 
        "Actions": [
            {
                "Type": "fixed-response", 
                "Order": 1, 
                "FixedResponseConfig": {
                    "ContentType": "text/html", 
                    "MessageBody": "<html>\n<head><title>404 Not Found</title></head>\n<body>\n<center><h1>404 Not Found</h1></center>\n<hr>\n</body>\n</html>", 
                    "StatusCode": "404"
                }
            }
        ]
    }, 
    {
        "Conditions": [
            {
                "Field": "path-pattern", 
                "Values": [
                    "*/composer.json", 
                    "*/Gruntfile.js",
                    "*.lock", 
                    "*/environtment.xml",
                    "*/readme.txt"
                ], 
                "PathPatternConfig": {
                    "Values": [
                        "*/composer.json", 
                        "*/Gruntfile.js",
                        "*.lock", 
                        "*/environtment.xml",
                        "*/readme.txt"
                    ]
                }
            }
        ], 
        "Actions": [ #### Same as above
            ...
        ]
    }, 
    {
        "Conditions": [
            {
                "Field": "path-pattern", 
                "Values": [
                    "*/fixtures/*", 
                    "*/behat/*", 
                    "*/phpunit.xml"
                ], 
                "PathPatternConfig": {
                    "Values": [
                        "*/fixtures/*", 
                        "*/behat/*", 
                        "*/phpunit.xml"
                    ]
                }
            }
        ], 
        "Actions": [ #### Same as above
            ...
        ]
    }
]

Documentation