Learn the basics of nginx

1. What is nginx?

nginx is a high-performance http and reverse proxy web server that takes up little memory and has strong concurrency. There are reports that nginx can reach up to 50,000 concurrent connections.

2. What can nginx do?

• Reverse Proxy
• Load Balancing
• Separation of static and dynamic
• High availability cluster

2.1 What is a forward proxy?

The client (browser) configures the proxy server and accesses the Internet through the proxy server.

2.2 What is a reverse proxy?

The client sends the request to the reverse proxy server, which retrieves the data and returns it to the client.

2.3 Load Balancing

The client sends multiple requests to the server. The server processes the requests and needs to interact with the database for some data. After the server completes the processing, it returns the results to the client.

If a single server cannot solve the problem, build a server cluster to achieve

2.4 Separation of static and dynamic

In order to improve the parsing speed of the website, dynamic pages and static pages are parsed by different servers to reduce the pressure on the original single server.

3. Basic operations of nginx

1. Before use, enter the nginx directory
2. Check the version number of nginx

./nginx -v

3. Start nginx

./nginx

4. Shut down nginx

./nginx -s stop

5. Reload nginx

./nginx -s reload

6. Check the status of nginx

ps -ef | grep nginx

3.1 nginx configuration file nginx/conf/nginx.conf

1. Global Block

Content from the configuration file to the events block.

2. Events block

The events block directive mainly affects the network connection between the nginx server and the user. The maximum number of connections supported by worker connections is 1024.

3.http block

3.2 Firewall settings

// View the open port number firewall-cmd --list-all

// Set the open port number firewall-cmd --add-service=http –permanent // Permanently open the http service in the firewall firewall-cmd --add-port=80/tcp --permanent // Permanently open port 80 in the firewall // Restart the firewall firewall-cmd –reload

IV. Reverse proxy implementation case

4.1.Nginx reverse proxy implementation example 1

Effect: Enter an address and jump to the tomcat homepage

Nginx configures reverse proxy, mainly forwarding requests through proxy_pass configuration

1. Hosts file domain name configuration

Configure the correspondence between domain name and IP in the hosts file of Windows system (Windods/System32/driver/etc/hosts on C drive)

2. Configuration of request forwarding in nginx (reverse proxy configuration) nginx.conf

Mainly modify the server_name and proxy_pass configurations:

• server_name: host IP
• proxy_pass: nginx proxy address

Test success

4.2Nginx reverse proxy implementation case 2

Use nginx reverse proxy to jump to different service ports according to the access path. The nginx listening port is 9001

1. Preparation

Deploy tomcat 8080

Deploy tomcat8081

Because the default port number of Tomcat is 8080, when setting the port number of Tomcat, you need to modify some ports in server.xml and start Tomcat.

Find webapps in the two tomcat files, create two files edu and vod in its directory, put the html page in them, and test whether the page can be successfully accessed.

2. Find the nginx configuration file nginx.conf

server {
    listen 9001;
    server_name 192.168.25.101;

    location ~ /edu/ {
        proxy_pass http://127.0.0.1:8080;
    }

    location ~ /vod/ {
        proxy_pass http://127.0.0.1:8081;
    }
}   

3. Open access ports 8080 8081 9001, otherwise it will not be accessible

4. Restart nginx and test

5. Load balancing implementation case

1. Achieve results

Enter an address http://192.168.17.129/edu/a.html in the browser address, and the load balancing effect is evenly distributed to ports 8080 and 8081.

2. Preparation

1. Deploy tomcat 8080, deploy tomcat 8081

2. In the webapps directory of the two tomcats, create a folder named edu and create two pages a.html in the folder for testing

3. Make corresponding configuration in the nginx configuration file and configure it under http

Upstream myserver{
    //Add server name server 192.168.17.129;8080;
    server 192.168.17.129;8081;
}

Then configure under servers and Locationa

server_name 192.168.17.129:
location /{
    proxy_pass http://myserver;
}

5.1nginx load balancing strategy

• Polling (default)

Each request is assigned to a different backend server in chronological order. If a backend server goes down, it can be automatically removed.

• weight

Weight represents the weight, the default value is 1, the higher the weight, the more clients are assigned

use:

Upstream myserver{
    //Add server name server 192.168.17.129;8080 weight =10;
    server 192.168.17.129;8081 weight = 20;
}

• ip_hash

Each request is assigned according to the hash result of the access IP, so that subsequent access to a fixed backend server can be made

• fair

Allocate based on response time.

Upstream myserver{
    //Add server name server 192.168.17.129;8080;
    server 192.168.17.129;8081;
    fair;
}

6. nginx dynamic and static separation

6.1 Implementation process

Specify different suffixes by location to achieve different request forwarding. By configuring the expires parameter, you can set a browser cache expiration time to reduce requests and traffic between the server and the server.

6.2 Examples

1. Prepare static resources

2. Specific configuration

• 1. Configure nginx/conf in the nginx configuration file

• 2. Enter the URL to access

7. Nginx configuration high availability

7.1 What is Nginx high availability?

As can be seen from the figure, for the previous operation mode, when there is only one nginx, the user's request is forwarded to different tomcats through nginx. When one of the nginx goes down, the service forwarding will fail. Therefore, by building an nginx cluster, when the main server nginx goes down, the backup server's ngnix will re-forward the user's request to tomcat, thereby ensuring high availability.

7.2. Nginx configuration high availability preparation

• Prepare two servers 192.168.17.129 and 192.268.17.131
• Install nginx on both servers
• Configuring a virtual address
• Install keepalived on both servers directly through yum

yum install keepalive -y

7.3 High Availability Configuration

Complete the keepalive configuration and find the keepalive configuration file keepalive.conf

(1) Modify the /etc/keepalived/keepalivec.conf configuration file

global_defs {
	notification_email {
	[email protected]
	[email protected]
	[email protected]
	}
	notification_email_from [email protected]
	smtp_server 192.168.17.129
	smtp_connect_timeout 30
	router_id LVS_DEVEL
}

vrrp_script chk_http_port {
	script "/usr/local/src/nginx_check.sh"
	interval 2 # (interval between detection script execution)
	weight 2
}

vrrp_instance VI_1 {
	state BACKUP # Change MASTER to BACKUP on the backup server
	interface ens33 //Network card virtual_router_id 51 # The virtual_router_id of the master and backup machines must be the same priority 90 # The master and backup machines have different priorities, the master has a larger value and the backup has a smaller value advert_int 1
	authentication
		auth_type PASS
		auth_pass 1111
	}
	virtual_ipaddress {
		192.168.17.50 // VRRP H virtual address }
}

(2) Add a detection script in /usr/local/src

A=`ps -C nginx –no-header |wc -l`
if [ $A -eq 0 ];then
	/usr/local/nginx/sbin/nginx
	sleep 2
	if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
		killall keepalived
	fi
fi

(3) Start nginx and keepalived on both servers. Start nginx: ./nginx
Start keepalived: systemctl start keepalived.service

7.4 Testing

1). Enter the virtual IP address in the browser address: 192.168.17.50

You can directly access

2) When the main server nginx and keepalived are stopped, the page can still be accessed when the virtual address is entered again

8. Working principle of nginx

master & worker

8.1. One master and multiple workers have advantages

• For each worker process, an independent process does not need to be locked, so the overhead caused by the lock is saved. At the same time, it will be much more convenient when programming and finding problems. You can use nginx –s reload hot deployment and use nginx for hot deployment operations.
• Each worker is an independent process. If one of the workers has a problem, the other workers continue to compete independently to implement the request process without causing service interruption.

8.2 How many wokers should be set?

• It is most appropriate that the number of workers is equal to the number of CPUs on the server. (For example: If your computer has 4 cores, setting 4 workers is enough; if it has 8 cores, setting 8 workers is enough)

8.3. Number of connections worker_connection

First: How many connections of woker are occupied by sending a request?
Answer: 2 or 4 Second question: nginx has one master and four workers. Each worker supports a maximum of 1024 connections. What is the maximum number of concurrent connections it supports?

• The maximum number of concurrent static accesses is: worker_connections * worker_processes / 2.
• If HTTP is used as a reverse proxy, the maximum number of concurrent connections should be worker_connections * worker_processes/4.

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