/etc/nginx/nginx.conf

Configuration contexts

Contexts found in an nginx configuration file include

global
event, contained within the global context
http
server, contained within the http, mail and/or stream context. Used to define virtual servers.
location, contained within a server context or nested within a parent location context
upstream
if, for conditional execution
limit_except
stream
mail

I believe that a context is formulated as a block with curly braces (so the hattp context is http { … }).

Compare these contexts with the value of type in ngx_module_s.

Testing syntax of configuration file

The syntax of the configuration file can be tested like so:

# /usr/sbin/nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

Reload config file after modification

After a modification of the config file, the (running) nginx process can be informed to reload it with

# /usr/sbin/nginx -s reload

Simple example

This is a simple example of an nginx configuration file. It is basically a slightly adapted version of that which I found after installing ningx with sudo apt install -t nginx.

#
# Specify the user and group by which worker processes are run.
# Because the group is omitted here, it defaults to the name
# of the user.
#
user www-data;

#
# Define the number of worker processes.
# Use the special value «auto» to bind worker processes
# automatically to available CPUs.
#
worker_processes auto;

#
# Specify the file where the main process' ID is stored:
#
pid /run/nginx.pid;

#
# The *.conf files included from /etc/nginx/modules-enabled
# typically contain a load_module statement which
# loads a shared library.
# These shared libraries are usually found in /usr/share/nginx/modules.
#
include /etc/nginx/modules-enabled/*.conf;

events {
        worker_connections 768;
        # multi_accept on;
}

http {

      #
      # Enable sendfile()
      # which is required when enabling tcp_nopush
      #
        sendfile on;

      #
      # Set the socket option TCP_CORK (or TCP_NOPUSH in BSD).
      # Requires sendfile to be set when enabled. 
      #
        tcp_nopush on;

      #
      # See this link.
      #
      # server_names_hash_bucket_size   64;
        types_hash_max_size           2048;

      # server_tokens off;

      # server_name_in_redirect off;

      #
      # Specify MIME types (default and depending on file suffix)
      #
        include /etc/nginx/mime.types;
        default_type application/octet-stream;

      #
      # SSL settings
      #
      # Enable the specified protocols (do not add SSLv3 because of Poodle attack)
      #
        ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;

        ssl_prefer_server_ciphers on;

      #
      # Specify location of log files.
      #
        access_log /var/log/nginx/access.log;
        error_log  /var/log/nginx/error.log;

      #
      # Enable compression
      #
        gzip on;

      #
      # Specify the MIME types which will be compressed.
      #
      # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;
        gzip_types *;

      # gzip_vary on;
      # gzip_proxied any;
      # gzip_comp_level 6;
      # gzip_buffers 16 8k;
      # gzip_http_version 1.1;

      #
      # Virtual Host Configs
      #
        include /etc/nginx/conf.d/*.conf;

      #
      # In a default configuration, the following directive
      # causes /etc/nginx/sites-available/default to be
      # included because /etc/nginx/sites-available/default is
      # a symbolic link to that file.
      #
        include /etc/nginx/sites-enabled/*;
}


#mail {
#       # See sample authentication script at:
#       # http://wiki.nginx.org/ImapAuthenticateWithApachePhpScript
#
#       # auth_http localhost/auth.php;
#       # pop3_capabilities "TOP" "USER";
#       # imap_capabilities "IMAP4rev1" "UIDPLUS";
#
#       server {
#               listen     localhost:110;
#               protocol   pop3;
#               proxy      on;
#       }
#
#       server {
#               listen     localhost:143;
#               protocol   imap;
#               proxy      on;
#       }
#}

Links

Configuration pitfalls and common mistakes.

https://wiki.debian.org/Nginx/DirectoryStructure