Nginx (pronounced "engine-x") is an open-source, high-performance **HTTP and reverse proxy server**, which can also be used as a mail proxy server. It is renowned for its stability, rich feature set, straightforward configuration, and low resource consumption. Nginx is good at handling high concurrency, and thanks to its event-driven and asynchronous architecture. This design allows Nginx to manage a large number of concurrent connections with minimal resource usage, making it an ideal choice for hosting high-traffic websites and applications. Nginx is also widely used for load balancing and HTTP caching, enhancing the performance of websites and applications. 

We have two ways to install Nginx: Yum installation and source code installation.

------------


# Yum installation (Recommended)

## Update yum version

```shell
sudo yum -y update
```

> Parameter `-y` is used to set all answer of confirmation question to 'yes'. It ensures that we can complete instruction steps continuously without being interrupted by confirmation question. If you want to view and confirm each question, do not use this parameter.

## Install EPEL repository

Nginx is not in the default yum source, we can use EPEL repository. Run this command to insatll EPEL repository:

```shell
sudo yum install -y epel-release
```

(In some Centos-like Linux system, ep: Redhat, Amazon Linux, installation of EPEL is not a necessary. If you find `No match for argument: epel-release `, you can just move to next step. ) 

## Install Nginx

Once the EPEL respsitory has been installed, we can now install Nginx:

```shell
sudo yum install -y nginx
```

After successful installation:
The default nginx website directory is: `/usr/share/nginx/html`
The default configuration file is: `/etc/nginx/nginx.conf`
The custom configuration file directory is: `/etc/nginx/conf.d/`

## Start Nginx Service

After Nginx benn installed, Nginx will not start automatically. To get Nginx running, use the `systemctl` command:

```shell
sudo systemctl enable nginx  // Set to start Nginx on boot
sudo systemctl start nginx  // Run nginx service
```

After Nginx service has been started, we can use this command to check its status:

```shell
sudo systemctl status nginx
```

The output should look like:

```shell
* nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2023-01-25 15:31:54 EST; 1min 20s ago
  Process: 22547 ExecStart=/usr/sbin/nginx (code=exited, status=0/SUCCESS)
  Process: 22544 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=0/SUCCESS)
  Process: 22542 ExecStartPre=/usr/bin/rm -f /run/nginx.pid (code=exited, status=0/SUCCESS)
 Main PID: 22550 (nginx)
   CGroup: /system.slice/nginx.service
           * 22550 nginx: master process /usr/sbin/nginx
           * 22551 nginx: worker process
           * 22552 nginx: worker process

Jan 25 15:31:54 User systemd[1]: Starting The nginx HTTP and reverse proxy server...
Jan 25 15:31:54 User nginx[22544]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
Jan 25 15:31:54 User nginx[22544]: nginx: configuration file /etc/nginx/nginx.conf test is successful
Jan 25 15:31:54 User systemd[1]: Started The nginx HTTP and reverse proxy server.
```

The active attribute on second row should be **active (running)**

Also, there are some useful `systemctl` command:

```shell
sudo systemctl restart nginx  // stop Nginx service
sudo systemctl reload nginx  // Reload, because generally after reconfiguration, you do not want to restart the service, you can use reload at this time.
```

## Config Nginx

Nginx configurations are located in `/etc/nginx/nginx.conf`. You might also want to look into the `/etc/nginx/conf.d/` directory for specific site configurations. Use a text editor like `vi` or `nano` to edit these files 

## Configure firewall to allow traffic (Optional)

If your server has opened a firewall, you need to run the following command to open ports 80 and 443

```shell
sudo firewall-cmd --permanent --zone=public --add-service=http
sudo firewall-cmd --permanent --zone=public --add-service=https
sudo firewall-cmd --reload
```

You can now test the Nginx installation by opening http://server_ip_or_domain_name/ in your web browser.
You should see the default Nginx welcome page.

Or you can check Nginx process:

```shell
ps -ef | grep nginx
```

The output should look like:


```shell
root     22550     1  0 15:31 ?        00:00:00 nginx: master process /usr/sbin/nginx
nginx    22551 22550  0 15:31 ?        00:00:00 nginx: worker process
nginx    22552 22550  0 15:31 ?        00:00:00 nginx: worker process
root     22558 22147  0 15:58 pts/0    00:00:00 grep --color=auto nginx

```

------------


# Source code installaton

## Install dependencies

Nginx depend on folloing module:

1. gcc
2. pcre-devel
3. zlib-devel
4. openssl
5. openssl-devel

Use this command to install necessery dependencies:

```shell
yum -y install gcc pcre-devel zlib-devel openssl openssl-devel
```

## Download and unzip the Nginx installation package

```shell
cd /
mkdir -p  www/server/nginx
cd /www/server/nginx
wget http://nginx.org/download/nginx-1.21.0.tar.gz
tar -xvf nginx-1.21.0.tar.gz
```

## Install Nginx service

```shell
cd /www/server/nginx/nginx-1.21.0	//Enter nginx directory
./configure --prefix=/usr/local/nginx	// installation configuration, check the system environment
make
make install
```

## Firewall enabled

Just like yum installation, use the same commands:

```shell
sudo firewall-cmd --permanent --zone=public --add-service=http
sudo firewall-cmd --permanent --zone=public --add-service=https
sudo firewall-cmd --reload
```

## Start Nginx service

```shell
cd /usr/local/nginx/sbin/
./nginx
```

Some useful command for change status of Nginx:

```shell
cd /usr/local/nginx/sbin	// Enter Nginx directory
./nginx				// Start Nginx service
./nginx -s stop		// Stop Nginx service
./nginx -s reload	// Reload Nginx service
./nginx -v			// Check Nginx version
```

After Nginx been installed, you can use the same way as yum installation to check if nginx has started successfully. Also, use the same way to set Nginx automaticlly start on boot.

Exploring the Efficient Installation and Configuration of Nginx: A Comprehensive Guide to Using Yum and Source Code Methods

Linux

Deploy Nginx on Centos 7