Mycpen

1. Install
[root@cPen_A lianxi]# yum install nfs-utils
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2. Modify the configuration file /etc/exports
[root@cPen_A lianxi]# vim /etc/exports        # Note: Configuration file
/opt/www 192.168.255.0/24(rw,no_root_squash)                
# Note: 192.168.255.0/24 shared, rw permission read and write, no_root_squash treats remote root users as local root users, i.e., does not restrict root.
First, create the /opt/www directory and create an index.html file under it with the content "this is test nfs".
Then add the exports configuration, NFS configuration: vim /etc/exports
Add the following line:
 /opt/www 192.168.255.0/24(rw)
Indicates sharing the /opt/www directory, allowing hosts in the 192.168.255.0/24 subnet to access my local /opt/www directory via NFS.
The options in parentheses () indicate options, rw means read and write.

Activate configuration:
exportfs -a or restart the service

[root@cPen_A opt]# cd /opt
[root@cPen_A opt]# mkdir www
[root@cPen_A opt]# cd www
[root@cPen_A www]# vim index.html
this is test nfs
[root@cPen_A www]# pwd
/opt/www

# Note: /opt is the directory for additional packages.
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3. Start the NFS service
[root@cPen_A www]# service nfs start        # Note: Start the service
[root@cPen_A www]# showmount -e            # Note: Check if it can connect
Export list for cPen_A:
/opt/www 192.168.255.0/24
# Note: Under centos8, start [root@cPen_B ~]# service nfs-server start
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NFS connection check
You can first self-test on the server side to see if it can connect.
Command: showmount [-ae] [hostname | IP]
-a: Display the current host and client NFS connection sharing status.
-e: Display the directory data shared by a certain host's /etc/exports.
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4. Test on another machine
If a return appears, it indicates ok.
[root@cPen_C ~]# showmount -e 192.168.255.28    # Note: Specify the IP address of the machine to analyze
Export list for 192.168.255.28:                    # Note: If this situation appears, it indicates that it can connect, and connectivity is not an issue.
 /opt/www 192.168.255.0/24

5. Mount network files
On another machine
[root@cPen_C ~]# mkdir /mnt2
[root@cPen_C ~]# mount -t nfs 192.168.255.28:/opt/www /mnt2        # Note: Mount network files
[root@cPen_C ~]# df            # Note: Use the df command to check disk mount status (this is a network disk mount).
192.168.255.28:/opt/www 17811456 2165760 15645696   13% /mnt2

[root@cPen_C ~]# cd /mnt2
[root@cPen_C mnt2]# ls
index.html
[root@cPen_C mnt2]# cat index.html 
this is test nfs
[root@cPen_C mnt2]# ls
index.html
[root@cPen_A ~]# cd /opt/www/                    # Note: Server A host operation
[root@cPen_A www]# touch index2.html            # Note: Server operation
[root@cPen_C mnt2]# ls
index2.html  index.html
[root@cPen_C mnt2]# mkdir index2.html
mkdir: cannot create directory "index2.html": Permission denied
# Note: Client C does not have permission to operate on server A files.
# If there is no permission, set no_root_squash in /etc/exports, and it can be operated.
no_root_squash treats remote root users as local root users, i.e., does not restrict root.
# Note: Let the server recognize the remote root user as the local root user.
# Note: After modifying the configuration file, you need to use exportfs -a to activate the configuration; then remount (first unmount, then remount).

# Example: Unmount
[root@cPen_C mnt2]# cd ..            # Note: Exit the mnt2 directory first, otherwise it will report busy.
[root@cPen_C /]# umount /mnt2        # Note: Then unmount.

# After modifying the configuration file, you need to use exportfs -a to activate.
# Remount:
    First exit the /mnt2 directory, then execute:
    umount /mnt2
    Then execute the mount.

Machine B becomes the proxy machine.
Step 1: Start port 8080.
Modify the nginx configuration on machines A, B, and C to start port 8080, binding the domain name www.sc.com.
# Note: Configuration file directory: /etc/nginx
# Note: Enter the /etc/nginx/conf.d directory and create sc.conf.
Enter the following content:
[root@cPen_A ~]# cd /etc/nginx/
[root@cPen_A nginx]# cd conf.d/
[root@cPen_A conf.d]# vim sc.conf        # Note: The suffix must be .conf, automatically loaded to read this configuration file.
server {
    listen  8080;                        # Note: Listen on port 8080.
    server_name  www.sc.com;            # Note: Specify the domain name.

    root /opt/www;                        # Note: Specify the website home directory, default to look for index.html in the home directory.

}
[root@cPen_A conf.d]# nginx -t            # Note: Perform syntax check.
[root@cPen_A conf.d]# nginx -s reload        # Note: Activate configuration.
[root@cPen_A conf.d]# lsof -i:8080        # Note: Port 8080 is up.
COMMAND  PID  USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
nginx   3193  root    6u  IPv4  50354      0t0  TCP *:webcache (LISTEN)
nginx   3194 nginx    6u  IPv4  50354      0t0  TCP *:webcache (LISTEN)
nginx   3195 nginx    6u  IPv4  50354      0t0  TCP *:webcache (LISTEN)

Use lsof -i:8080 to check if the port is started.
Use curl -H "Host: www.sc.com" http://192.168.0.73:8080 to check if the returned content is consistent.
Access port 8080 of 192.168.0.68 using the domain name www.sc.com.
[root@cPen_A ~]# curl -H "Host: www.sc.com" http://192.168.0.73:8080
this is test nfs
# Note: The content returned by the three machines is the same, all are this is test nfs.

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# Note: Add reverse proxy on machine B.
Perform load balancing on machine B: forward requests to other machines (proxy forwarding) (high availability).
[root@cPen_B conf.d]# vim sc.conf 
server {
    listen  8080;
    server_name  www.sc.com;    

    root /opt/www;

}

upstream sc {                        # Note: Proxy forwarding, naming upstream as sc.
    server 192.168.0.73:8080;
    server 192.168.0.53:8080;
    server 192.168.0.79:8080;
}
# Note: Virtual host, allowing different domain names to do different things.
server {                            
    listen  80;
    server_name  www.sc.com;        

    root /opt/www;

    location / {                        # Note: Accessing the / directory of the website will be forwarded to sc.
        proxy_set_header Host $host;    # Note: Header information, if not added, it may become the address of machine B.
        # Note: Ensure that the header host field information sent by the client and the header host field of the forwarded packet remain consistent.
        proxy_pass http://sc;            # Note: Set the backend proxy server.
    }
}

server {
    listen  80;
    server_name  www.sc1.com;

    root /usr/share/www;

    location / {
        proxy_set_header Host $host;
        proxy_pass http://sc;
    }
}

# Note: When outputting www.sc.com, the request will have the packet storing the host header information: www.sc.com. After receiving this packet on port 80, it knows to forward it to port 8080. Machine B helps you request the 8080 ports of A, B, and C.
# Note: The client initiates a request to www.sc.com, the host header information is www.sc.com (the header information carried by the request packet), machine B hands it to the corresponding server for processing, requesting machine B's port 80 for processing, forwarding to port 8080. When machine B receives the packet, it hands it to the server for processing. At this time, the header information of the packet initiated by A may be the IP address of B (not www.sc.com), and the server_name of port 8080 will fail to forward if it does not have B's IP address. Therefore, proxy_set_header Host $host keeps their header information consistent.

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# Activate configuration
[root@cPen_B conf.d]# nginx -t
[root@cPen_B conf.d]# nginx -s reload

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# Then access port 80 multiple times to check if the returned content is consistent, and check if each machine's /var/log/nginx/access.log log has new requests coming in. tail -f /var/log/nginx/access.log

[root@cPen_B conf.d]# curl -H "Host: www.sc.com" http://192.168.0.79
this is test nfs
# Note: Proxy forwarding, accessing port 80, forwarding to port 8080, distributed to 3 machines for execution (load balancing).

[root@cPen_C conf.d]# tail -f /var/log/nginx/access.log     # Note: On machine C, machine B helps request.
192.168.0.79 - - [01/Dec/2020:17:21:54 +0800] "GET / HTTP/1.0" 200 17 "-" "curl/7.61.1" "-"
# Note: Average distribution to 3 machines, default round-robin.