user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;

# Load modules
include              /etc/nginx/modules-enabled/*.conf;

events {
    worker_connections 1024;
    multi_accept on;
}

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

    charset                utf-8;
    sendfile               on;
    tcp_nopush             on;
    tcp_nodelay            on;
    server_tokens          off;

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

    log_format cloudflare '$remote_addr - $remote_user [$time_local] "$request" '
                          '$status $body_bytes_sent "$http_referer" '
                          '"$http_user_agent" $http_cf_ray $http_cf_connecting_ip '
                          '$http_x_forwarded_for $http_x_forwarded_proto ' 
                          '$http_true_client_ip $http_cf_ipcountry '
                          '$http_cf_visitor $http_cdn_loop';

    log_format json_combined escape=json '{'
        '"method":"$request_method",'
        '"scheme":"$scheme",'
        '"domain":"$host",'
        '"uri":"$request_uri",'
        '"query_string":"$query_string",'
        '"referer":"$http_referer",'
        '"content_type":"$sent_http_content_type",'
        '"status": $status,'
        '"bytes_sent":$body_bytes_sent,'
        '"request_time":$request_time,'
        '"user_agent":"$http_user_agent",'
        '"cache":"$upstream_cache_status",'
        '"upstream_time": "$upstream_response_time",'
        '"timestamp":"$time_iso8601",'
        '"ip":"$http_x_forwarded_for"'
    '}';

    # log_format VCOMBINED '$host:$server_port '
    #                  '$remote_addr $remote_user [$time_local] '
    #                  '"$request" $status $body_bytes_sent '
    #                  '"$http_referer" "$http_user_agent"';


    # track every client request and are vital for traffic analysis and performance monitoring.
    access_log  /var/log/nginx/access.log json_combined;
    # capture internal server issues and help with troubleshooting.
    error_log   /var/log/nginx/error.log debug;
    
    # SSL
    # Mozilla Intermediate configuration
    ssl_protocols          TLSv1.2 TLSv1.3;
    ssl_ciphers            ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;
    ssl_prefer_server_ciphers on;
    # enable session resumption to improve https performance
    ssl_session_timeout    10m;
    ssl_session_cache      shared:SSL:10m;
    ssl_session_tickets    off;

    # Diffie-Hellman parameter for DHE ciphersuites
    # ssl_dhparam            /etc/nginx/dhparam.pem;

    # OCSP Stapling 
    # ssl_stapling           on;
    # ssl_stapling_verify    on;
    resolver               127.0.0.11 1.1.1.1 1.0.0.1 8.8.8.8 8.8.4.4 208.67.222.222 208.67.220.220 valid=60s;
    resolver_timeout       2s;


    #       CONTROL RESOURCES AND LIMITS / CONTROLLING BUFFER OVERFLOW ATTACKS
    # specify the client request body buffer size; default 8k/16k
    client_body_buffer_size 1k;
    # sets the headerbuffer size for the request header from client.
    # 1K sufficient for most requests. 
    # Increase this if you have a custom header or a large cookie sent from the client (e.g., wap client).
    client_header_buffer_size 1k;
    # assigns the maximum accepted body size of client request, indicated by the line Content-Length in the header of request. 
    # If size is greater the given one, then the client gets the error “Request Entity Too Large” (413). 
    # Increase this when you are getting file uploads via the POST method. e.g harbor image push, minio uploads
    client_max_body_size 1k;
    # assigns the maximum number and size of buffers for large headers to read from client request. 
    # By default the size of one buffer is equal to the size of page, depending on platform this either 4K or 8K, 
    # if at the end of working request connection converts to state keep-alive, 
    # then these buffers are freed. 2x1k will accept 2kB data URI. 
    # This will also help combat bad bots and DoS attacks. 
    large_client_header_buffers 4 4k;

    client_header_timeout  60;
    client_body_timeout    60;
    send_timeout           60;

    #       PROXY BUFFERING
    # NGINX stores the response from a server in internal buffers as it comes in, 
    # and doesn't start sending data to the client until the entire response is buffered

    # With proxy_buffering disabled, data received from the server is immediately relayed by NGINX, 
    # allowing for minimum Time To First Byte (TTFB). 
    # TLDR - Buffering is needed to ensure that the upstream server can be set free after delivering the response to NGINX, 
    #        and NGINX will proceed to deliver the response to the slow client.
    proxy_buffering off; # for a single server setup (SSL termination of Varnish), where no caching is done in NGINX itself
    # Defines the amount of memory that NGINX will allocate for each request to the proxied server. 
    # This small chunk of memory will be used for reading and storing the tiny fraction of response – the HTTP headers.
    # tuning solves the upstream sent too big header while reading response header from upstream error.
    proxy_buffer_size 8k; # defaults: 4k/8k, should be enough for most PHP websites, or adjust as above
    # size of buffers, in kilobytes, which can be used for delivering the response to clients 
    # while it was not fully read from the upstream server.
    proxy_busy_buffers_size 16k; # essentially, proxy_buffer_size + 2 small buffers of 4k
    # The rule of thumb with this setting is that while we make use of buffering, 
    # it is best that the complete response from upstream can be held in memory, to avoid disk I/O.
    proxy_buffers 8 4k; # Default: 8 4k|8k; should be enough for most PHP websites, adjust as above to get an accurate value

    # Time to establish TCP connection
    # Increase only if your app has slow endpoints
    proxy_connect_timeout 60s;
    # Time between successive writes to upstream
    proxy_send_timeout 60;
    # Time between successive reads from upstream
    proxy_read_timeout 60;

    # Gzip Settings
    gzip on;
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_types text/plain text/css text/xml text/javascript application/json application/javascript application/xml+rss application/rss+xml font/truetype font/opentype application/vnd.ms-fontobject image/svg+xml;

    # Include all server configurations
    # include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;
}