Using OpenNJet HA Copilot to achieve high availability deployment (1)

From data to large model application, on November 25th, Hangzhou Yuanchuang Conference was held to share development tips.

NGINX evolves to cloud native, All in OpenNJet

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1. Introduction to HA

When deploying server applications, in order to achieve high availability of the service, a common solution is to additionally install Keepalived, monitor the running status of the server application through Keepalived, and set up a virtual IP (VIP). The client accesses the server through VIP. Example. Taking the open source Nginx as an example, the diagram is as follows:

 

Keepalived is based on the VRRP protocol, which stands for Virtual Router Redundancy Protocol. The virtual routing redundancy protocol can be considered as a protocol to achieve high availability of routers. N routers that provide the same functions are formed into a router group. This group has a master and multiple backups. The master has a VIP (VIP) that provides services to the outside world. Virtual IP Address) (the default route of other machines in the LAN where the router is located is VIP), the master will send multicast, and when the backup cannot receive the VRRP packet, it will consider the master to be down. At this time, it is necessary to prioritize the VRRP level to elect a backup as master. In this way, the high availability of the router can be ensured.

In order to simplify deployment and configuration, NJet implements the HA module of the VRRP protocol through the Copilot extension mechanism. As long as HA Copilot is loaded and the corresponding configuration file is provided, the high availability function can be achieved. The schematic diagram is as follows:

2. Configuration instructions

To enable the HA function, you need to add the following instructions in the main block of njet.conf

helper ha modules/njt_helper_ha_module.so conf/vrrp.conf;

And provide the vrrp configuration file in the conf directory. The description of the configuration items is as follows.

 

Configuration items	Required	Configuration instructions
vrrp_instance	yes	The string of vrrp_instance is the set VRRP instance name.
state	yes	Set the initialization status of the current node, the status is MASTER or BACKUP
interface	yes	You can bind the VIP interface name, such as eth0, bond0, br0. View your network card information through IP -a
nopreempt	no	Set whether to preempt the virtual IP. If added, it will not preempt.
virtual_router_id	yes	Set the unique ID of the virtual router, range: 0-255. Multiple njet nodes belonging to the same cluster have the same ID. The value must be different in different njet clusters. Be sure to confirm that this value must be unique in the same network.
priority	yes	Set the priority of the current njet node, range: [1-254], the larger the value, the higher the priority.
virtual_ipaddress	yes	Set the subnet mask corresponding to the virtual IP

For configuration sample files, see the test verification chapter below.

3. Test verification

• Configure three server test machines, the IPs are:

1. 192.168.40.157
2. 192.168.40.158
3. 192.168.40.149

• Use virtual IP:

1. 192.168.40.50

The 192.168.40.157 server vrrp.conf configuration is as follows:

vrrp_instance m{
    state MASTER
    interface eth192
    virtual_router_id 32 
    priority 200 
    virtual_ipaddress {
         192.168.40.50/24 
    }
}

 

The 192.168.40.158 server vrrp.conf configuration is as follows:

vrrp_instance m{
    state BACKUP
    interface eth192
    virtual_router_id 32 
    priority 100 
    virtual_ipaddress {
          192.168.40.50/24 
    }
}

The 192.168.40.149 server vrrp.conf configuration is as follows:

vrrp_instance m{
    state BACKUP
    interface eth192
    virtual_router_id 32 
    priority 10 
    virtual_ipaddress {
        192.168.40.50/24 
    }
}

When NJet is started on all three servers , since 40.157 is the MASTER , the host will obtain the VIP :

 

 

 

After stopping the NJet instance on the 40.157 host, since the priority of the 40.158 host is higher, 40.158 will get the VIP:

 

 

 

After restarting the NJet instance on the 40.157 host, 40.157 will regain the VIP.

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OpenNJet was first based on the basic fork of NGINX1.19 and evolved independently. It has the characteristics of high performance, stability, and easy expansion. It also solves the long-standing problems of NGINX such as difficulty in dynamic configuration and management functions affecting business.

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