DigitalOcean – Fix NGINX Server Port 80 Refused on Ubuntu

Please don't post multiple questions in one.

The first step, when you don't know how something works, is to search for the documentation. In the case of nginx, directives are exhaustively explained through the official documentation directive index.

1. It depends on the location block nature. Prefixed location blocks order is not important, but regex location blocks order is, since the first one matching the request URI will be picked.

2. Configuration directives order does not matter except for few cases like if blocks. Gzip directives are not part of these.

3. In fact ssl on is the old way to do it and the listen directive parameter ssl is the new one. The usage of ssl on forces the server block to accept HTTPS only while the usage of the listen directive parameter allows to handle both HTTP and HTTPs in the same server block.

4. Actually you explicitely asked nginx to do this. Another way to have the same result is using return 301 https://domain.com$request_uri. The rewrite patten ^(.*) matches all URIs and capture them. Then it rewrites them permanently (301 redirect) to https://domain.com<uri>. Refer to the documentation to understand how the rewrite directive works if you are confused.

5. Opinion-based questions do not fit SF standards.

Found a much simpler solution. Following what CodeIgniter does behind the scenes for clean URL's; in Apache this rewrite works by sending each request as http://example.com/index.php?/controller/method which is then processed by CodeIgniter so your config.php should look like

$config['base_url'] = 'http://example.com'
$config['index_page'] = '';
$config['uri_protocol'] = 'REQUEST_URI';

To achieve the same in nginx you'd have to rewrite each request in identical way. Fine tuned my nginx configuration with:

location /example {

    root /var/www/html/;
    index index.php;

    location ~ ^/example/(.+\.php)$ {

        fastcgi_buffer_size 128k;
        fastcgi_buffers 256 4k;
        fastcgi_busy_buffers_size 256k;
        fastcgi_temp_file_write_size 256k;
        root /var/www/html/;
        include /etc/nginx/snippets/fastcgi-php.conf;
    }

    location ~* ^/example/(.+\.(jpg|jpeg|gif|css|png|js|ico|html|xml|txt)) {
        root /var/www/html/;
    }

    # Enforce SSL
    if ($scheme = http) {
        return 301 https://$host$request_uri;
    }

    # CI rewrite rules
    if ($host ~* ^www\.(.*)) {
        set $host_without_www $1;
        rewrite ^/(.*)$ $scheme://$host_without_www/$1 permanent;
    }

    if ($request_uri ~* ^(/example/(US|EU|INT)/(en|de)(.*))?$) {
        rewrite ^/(.*)$ /example/index.php?/$1 last;
    }

    if ($request_uri ~* ^(/example/(US|EU|INT)/(en|de)/(.*))?$) {
        rewrite ^/(.*)$ /example/index.php?/$1 last;
    }

    # catch all
    error_page 404 /index.php;
}

The missing link existed in nginx rewrite debug log so if you want to know about your rewrite rules and whether they are matched against your rule set add this to your nginx configuration:

server{
  ...
  rewrite_log on;
  error_log /var/log/nginx/error.log info;
  ...
}

And nginx will give you each request log with a match or no match against your PCRE regex. From here on you can tweak your configuration. I had to prepend path (directory) example in nginx configuration file for rewrite rules to work as expected.