Introduction to Nginx

Main Functions: Reverse Proxy, Load Balancing, Static/Dynamic Separation

1. Installlation and startup of Nginx
2. Common commands for Nginx, navigate to /usr/local/nginx/sbin

./nginx -- start Nginx

./nginx -s stop -- stop Nginx

./nginx -s quit -- graceful shut down Nginx

./nginx -s reload -- reload configuration, useful after config file changes

ps -ef|grep nginx -- check running Nginx processes

3. Overview of Nginx Features

Reverse Proxy: Handles requests directed to backend servers

Forward Proxy: Manages client-side requests

Different business needs can be addressed through customized routing rules

4. Load Balancing Strategies

Typical methods include: Round Robin (common), Weighted Round Robin (common), IP Hash

5. Configuration File Structure: nginx.conf

...              # Global context

events {         # Events context
   ...
}

http      # HTTP context
{
    ...   # HTTP global context
    server        # Server context
    { 
        ...       # Server global context
        location [PATTERN]   # Location context
        {
            ...
        }
        location [PATTERN] 
        {
            ...
        }
    }
    server
    {
      ...
    }
    ...     # HTTP global context
}

1. Global Context: Directives that affect the entire Nginx instance. Includes settings like user/group, PID file path, log directory, inclusion of config files, and number of worker processes.
2. Events Context: Controls network connections between Nginx and clients. Configures maximum connections per process, event handling model (e.g., epoll), and concurrent connection acceptance.
3. HTTP Context: Contains most configurasions for HTTP functionalities and third-party modules. Includes file inclusions, MIME types, custom logging, sendfile usage, timeout values, and request limits per connection.
4. Server Context: Defines virtual host parameters. Multiple servers can exist within one HTTP block.
5. Location Context: Specifies how to handle different URL paths and related page responses.

Sample Configuration:

########### Each directive must end with a semicolon #########
#user administrator administrators;  # User/group settings, default is nobody nobody.
#worker_processes 2;  # Number of worker processes, default is 1
#pid /nginx/pid/nginx.pid;   # Path to the PID file
error_log log/error.log debug;  # Log path and level. Can be set globally, in http, or server blocks. Levels: debug|info|notice|warn|error|crit|alert|emerg
events {
    accept_mutex on;   # Serialize network connections to prevent thundering herd, default is on
    multi_accept on;  # Allow a process to accept multiple connections, default is off
    #use epoll;      # Event model selection: select|poll|kqueue|epoll|resig|/dev/poll|eventport
    worker_connections  1024;    # Maximum connections per worker, default is 512
}
http {
    include       mime.types;   # File extension to MIME type mapping
    default_type  application/octet-stream; # Default MIME type, default is text/plain
    #access_log off; # Disable access logs    
    log_format myFormat '$remote_addr–$remote_user [$time_local] $request $status $body_bytes_sent $http_referer $http_user_agent $http_x_forwarded_for'; # Custom log format
    access_log log/access.log myFormat;  # 'combined' is the default format
    sendfile on;   # Enable sendfile transfer, default is off. Can be used in http, server, or location blocks.
    sendfile_max_chunk 100k;  # Max chunk size per transfer, default is 0 (no limit).
    keepalive_timeout 65;  # Connection timeout, default is 75s, configurable in http, server, or location blocks.

    upstream mysvr {   
      server 127.0.0.1:7878;
      server 192.168.10.121:3333 backup;  # Hot standby
    }
    error_page 404 https://www.baidu.com; # Error page redirection
    server {
        keepalive_requests 120; # Max requests per connection.
        listen       4545;   # Listening port
        server_name  127.0.0.1;   # Listening address       
        location  ~*^.+$ {       # URL filtering via regex, ~ case-sensitive, ~* case-insensitive.
           #root path;  # Root directory
           #index vv.txt;  # Default page
           proxy_pass  http://mysvr;  # Forward request to defined server group
           deny 127.0.0.1;  # Deny specific IPs
           allow 172.18.5.54; # Allow specific IPs           
        } 
    }
}