> For the complete documentation index, see [llms.txt](https://ankit-apdc.gitbook.io/system-design/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ankit-apdc.gitbook.io/system-design/building-blocks/nginx.md). # Nginx ## What is a web-server * When a user search for a page on a web-browser * Request is initiated by browser, leaving your LAN (Local Area Network) * DNS Lookup * TCP3 Handshake * SSL4 Handshake * HTTP and Get Request * Request then travel through Global Area Network * Then reaches to computer/server which needs to serve the request * Similar route in reverse direction for response * The server/computer that serve the web-pages or provide response to requests is web-server * Every web server has an IP address and a Domain name * Request is served by web-server, an application is required to make a computer, a web-server * Few examples for web-server software in market: * XAMPP * Apache * Nginx * Tornado * Caddy * Microsoft IIS ## what is Ngnix * Open source software, objective is to reduce web-page load time * Used for: * Reverse proxying, Caching, Load Balancing * Provides HTTP server capabilities * Also functions as proxy server for email (IMAP, POP and SMTP) * Mainly designed for maximum performance and stability * Uses a non-threaded and event-driven architecture ## Nginx Architecture * Uses master-slave architecture by supporting event-driven, asynchronous, and non-blocking model ![](https://679135566-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Ma8GKQU92FWew4_578V%2F-Mf1CmANKyvjRfs6aMVQ%2F-Mf1CvbvGk5qLyx8_6PS%2Fimage.png?alt=media\&token=435cd575-65d1-4d2c-9585-24e41f6d572a) **Master: Responsible for** * Reading and validating configuration * Starting, terminating and maintaining required number of workers and number of processes within each worker * Re-configuring without any service interruption * Re-opening for log files * Compile embedded for scripts **Cache Loader: responsible for** * Checking on-disc cache items and populating nginx in-memory database with the cache metadata * Prepares nginx instances to work with files already available in the disc, arranged in specific allocated directory structure * Cache loaded traverses the directory structure, checks cache content with the meta-data, updates relevant entry and also checks if everything is clean when system exists **Cache-Manager: responsible for** * Cache expiration and termination management ## **Why to use Nginx** * Easy to install and maintain * Improves Performance * Offers Scalability * Reduce the wait time for users * Load Balancing * On the fly upgrades (no downtime when upgrading) ## Nginx Installation * Install Nginx * Adjust Firewall * Check your server * Manage the Nginx Process ```bash sudo apt-get update sudo apt-get install nginx # install nginx sudo ufw enable # enable firewall nginx -v # check nginx installation status sudo ufx app list # listing apps with firewall sudo ufw allow "Nginx full" # to enable both encrypted and unencrypted graphic sudo ufw status sudo systemctl status nginx ``` ### Manage Nginx Processes, Basis Commands ```bash sudo systemctl stop nginx # stop nginx web-server sudo systemctl restart nginx # stop and start the service again sudo systemctl reload nginx # if making configuration changes, reload without stop sudo systemctl disable nginx # To not let nginx automatically start when server boots sudo systemctl enable nginx # to enable server automatically start at boot sudo nginx -t # to test config file ``` ### Important Directories and Files #### **Content** * ***/var/www/html***: The actual web content, which by default only consists of the default Nginx page you saw earlier, is served out of the /var/www/html directory. This can be changed by altering NGINX configuration files. #### **Server Configuration** * ***/etc/nginx***: The NGINX configuration directory. All of the Nginx configuration files reside here. * ***/etc/nginx/nginx.conf***: The main NGINX configuration file. This can be modified to make changes to the NGINX global configuration. * ***/etc/nginx/sites-available/***: The directory where per-site “server blocks” can be stored. NGINX will not use the configuration files found in this directory unless they are linked to the sites-enabled directory (see below). Typically, all server block configuration is done in this directory, and then enabled by linking to the other directory. * ***/etc/nginx/sites-enabled/***: The directory where enabled per-site “server blocks” are stored. Typically, these are created by linking to configuration files found in the sites-available directory. * ***/etc/nginx/snippets***: This directory contains configuration fragments that can be included elsewhere in the NGINX configuration. Potentially repeatable configuration segments are good candidates for refactoring into snippets. #### **Server Logs** * ***/var/log/nginx/access.log***: Every request to your web server is recorded in this log fil unless and until NGINX is configured to do otherwise. * ***/var/log/nginx/error.log***: Every NGINX error will be recorded in this log only. ### Configuration Settings * Core settings of the Nginx are mainly configured in the nginx.conf file * The configuration file is mainly structured into contexts * Most important settings are: * worker\_processes (How many workers, depends on number of core) * worker\_connections (How many requests can be served simultaneously) * access log and error log (for debugging) * gzip (compression of nginx responses) ### Load Balancing with Nginx ### Reverse Proxying with Nginx ## More Topics ### Web-Application Firewalls ### Cryptographic Sections - Certificates and SSL Terminations ### Security Aspects Related to Web-Servers ## Performance Tuning and Response Monitoring ## Reference for Further Reading * Edureka Youtube Video Lecture *