Default Nginx Configuration

To examine the default configuration files for Nginx, inspect /etc/nginx/nginx.conf. The end of this file typically includes directives that load all .conf file from /etc/nginx/conf.d/.

Check the contents of /etc/nginx/conf.d/:

ls /etc/nginx/conf.d/

By default, two configuration files exist: nginx.conf and default.conf.

The primary sections of the nginx.conf file are:

Section One:

• user: Sets the system user under which Nginx operates
• worker_processes: Defines the number of worker processes
• error_log: Specifies the path to the error log
• pid: Indicates where the process ID file is stored

Section Two (Events):

• worker_connections: Sets the maximum number of connections per worker
• use: Determines the event model used (e.g., epoll, select)

Section Three:

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    keepalive_timeout  65;

    include /etc/nginx/conf.d/*.conf;
}

Detailed File Analysis

Below is an annotated version of a typical nginx.conf configuration:

# User and group for running Nginx
user www www;

# Number of worker processes, ideally matching CPU cores
worker_processes 8;

# Global error logging level
error_log /usr/local/nginx/logs/error.log info;

# Process identifier file
pid /usr/local/nginx/logs/nginx.pid;

# Maximum number of open file descriptors per worker
worker_rlimit_nofile 65535;

events {
    # Event handling model (epoll recommended for Linux)
    use epoll;

    # Maximum connections per worker
    worker_connections 65535;

    # Keep-alive timeout
    keepalive_timeout 60;

    # Buffer size for client headers
    client_header_buffer_size 4k;

    # Open file cache settings
    open_file_cache max=65535 inactive=60s;
    open_file_cache_valid 80s;
    open_file_cache_min_uses 1;
    open_file_cache_errors on;
}

http {
    # MIME types mapping
    include /etc/nginx/mime.types;

    # Default content type
    default_type application/octet-stream;

    # Hash table size for server names
    server_names_hash_bucket_size 128;

    # Client header buffer size
    client_header_buffer_size 32k;

    # Large client header buffers
    large_client_header_buffers 4 64k;

    # Maximum body size
    client_max_body_size 8m;

    # Enable sendfile for efficient file transfer
    sendfile on;

    # TCP optimizations
    tcp_nopush on;
    tcp_nodelay on;

    # Keep-alive timeout
    keepalive_timeout 120;

    # FastCGI parameters
    fastcgi_connect_timeout 300;
    fastcgi_send_timeout 300;
    fastcgi_read_timeout 300;
    fastcgi_buffer_size 64k;
    fastcgi_buffers 4 64k;
    fastcgi_busy_buffers_size 128k;
    fastcgi_temp_file_write_size 128k;

    # Gzip compression
    gzip on;
    gzip_min_length 1k;
    gzip_buffers 4 16k;
    gzip_http_version 1.0;
    gzip_comp_level 2;
    gzip_types text/plain application/x-javascript text/css application/xml;
    gzip_vary on;

    # Load balancing setup
    upstream piao.jd.com {
        server 192.168.80.121:80 weight=3;
        server 192.168.80.122:80 weight=2;
        server 192.168.80.123:80 weight=3;
    }
}

Virtual Host Configuration

The virtual host configuration is located at /etc/nginx/conf.d/default.conf:

server {
    listen 80;
    server_name www.jd.com jd.com;
    index index.html index.htm index.php;
    root /data/www/jd;

    location ~ .*\.(php|php5)?$ {
        fastcgi_pass 127.0.0.1:9000;
        fastcgi_index index.php;
        include fastcgi.conf;
    }

    location ~ .*\.(gif|jpg|jpeg|png|bmp|swf)$ {
        expires 10d;
    }

    location ~ .*\.(js|css)?$ {
        expires 1h;
    }

    log_format access '$remote_addr - $remote_user [$time_local] "$request" '
                     '$status $body_bytes_sent "$http_referer" '
                     '"$http_user_agent" $http_x_forwarded_for';

    access_log  /usr/local/nginx/logs/host.access.log  main;
    access_log  /usr/local/nginx/logs/host.access.404.log  log404;

    location / {
        proxy_pass http://127.0.0.1:88;
        proxy_redirect off;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $host;
        client_max_body_size 10m;
        client_body_buffer_size 128k;
        proxy_intercept_errors on;
        proxy_connect_timeout 90;
        proxy_send_timeout 90;
        proxy_read_timeout 90;
        proxy_buffer_size 4k;
        proxy_buffers 4 32k;
        proxy_busy_buffers_size 64k;
        proxy_temp_file_write_size 64k;
    }

    location /NginxStatus {
        stub_status on;
        access_log on;
        auth_basic "NginxStatus";
        auth_basic_user_file confpasswd;
    }

    location ~ .\.(jsp|jspx|do)?$ {
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://127.0.0.1:8080;
    }

    location ~ .*\.(htm|html|gif|jpg|jpeg|png|bmp|swf|ioc|rar|zip|txt|flv|mid|doc|ppt|
    pdf|xls|mp3|wma)$ {
        expires 15d;
    }

    location ~ .*\.(js|css)?$ {
        expires 1h;
    }
}

Log Format Definitions

HTTP Request Structure

Nginx handles HTTP requests built upon TCP. A complete HTTP request consists of a request and resposne.

Request components: Request line, headers, and body.

Response components: Status line, headers, and body.

Viewing a full HTTP request via command line:

curl -v https://coding.imooc.com > /dev/null

The output shows the request (> part) and response (< part).

Nginx Log Types

• error.log: Records errors related to HTTP requests and Nginx service issues
• access_log: Logs each HTTP request processed

Log formatting uses log_format to combine variables into readable logs.

Example configuration:

Syntax: log_format name [escape=default|json] string …;
Default: log_format combined "...";
Context: http

Available Variables in Log Formats

• HTTP request variables like arg_PARAMETER, http_HEADER, send_http_HEADER
• Built-in variables provided by Nginx
• Custom-defined variables

Sample custom log format:

log_format custom '$remote_addr [$time_local] $request $status';

After saving changes, validate the configuration:

nginx -t -c /etc/nginx/nginx.conf

Then reload the service:

nginx -s reload -c /etc/nginx/nginx.conf

Testing the configuration:

curl 127.0.0.1
curl 127.0.0.1

Default log format variables:

• $remote_addr: Client IP address
• $remote_user: Authenticated username
• $time_local: Time of request
• $request: Request line
• $status: Response status code
• $body_bytes_sent: Size of response body sent
• $http_referer: Referring page
• $http_user_agent: Browser agent string
• $http_x_forwarded_for: Forwarded IP addresses

Built-in Variables

• $args: Query string from URL
• $content_length: Content-Length header
• $content_type: Content-Type header
• $document_root: Root directory of currrent request
• $host: Host header or server name
• $http_user_agent: User-Agent header
• $http_cookie: Cookie header
• $limit_rate: Connection rate limit
• $request_method: HTTP method (GET, POST)
• $remote_addr: Client IP address
• $remote_port: Client port
• $remote_user: Authenticated user
• $request_filename: Full path to requested file
• $scheme: Protocol (http, https)
• $server_protocol: HTTP protocol version
• $server_addr: Server IP address
• $server_name: Server name
• $server_port: Port number
• $request_uri: Original URI including query string
• $uri: Current URI without query string
• $document_uri: Same as $uri

Example with URL http://localhost:88/test1/test2/test.php:

• $host: localhost
• $server_port: 88
• $request_uri: http://localhost:88/test1/test2/test.php
• $document_uri: /test1/test2/test.php
• $document_root: /var/www/html
• $request_filename: /var/www/html/test1/test2/test.php