Virtual IP address failover for Applications Manager

Overview

Failover is an alternative monitoring mechanism that facilitates switching to a secondary/backup server when the primary server becomes unavailable. Configuring Applications Manager’s dual server failover system ensures constant availability so you can monitor all your business-critical applications without any interruptions. Learn more.

A Virtual IP address for failover is a shared IP address used by primary and secondary servers that belong to the same subnet. The virtual IP points to the secondary/backup server in case the primary server goes down. This way, the user can access both the primary and secondary/backup servers using a single IP address.

How it works

• If the primary Applications Manager server is up and working, a Virtual IP address will be assigned to it.
• In case the primary Applications Manager server goes down, the Virtual IP address will be dissociated from it and will instead be assigned to the secondary/backup server which will then take over the primary server’s function.
• This way the end user will always be able to access the application via a single IP address.

Prerequisites

The following are the prerequisites that need to be implemented before configuring the VIP Failover mode:

• Virtual IP Address and Hostname:
  
  • Virtual IP address: A shared IP address for both primary and secondary servers on the same subnet. It points to the active server when the other is down.
  • Virtual Host Name (optional): The hostname for the Virtual IP address. It should resolve to the corresponding Virtual IP address and vice versa.
• Hardware and software requirements:
  • Install the same edition of Applications Manager on both servers.
  • Ensure both servers use the same port and protocol (http/https).
• Network requirements:
  • Both the primary and secondary servers must have static IPv4 addresses.
  • The Virtual IP must also be static and in IPv4 format.
  • Both servers should be able to determine each other's IP addresses and hostnames.
  • The IP and Virtual IP addresses of both servers must belong to the same subnet.
  • Both servers should have high-speed connectivity and sufficient bandwidth.
  • Ensure the incoming traffic flow, including EUM, RUM, APM insight agents, and SNMP traps, is configured to use the VIP as the destination.
• Firewall Configuration:
  • Once the VIP is operational, traffic and polling can be initiated using either the Virtual IP (VIP) address or the Primary/Secondary IP address.
  • Include the VIP address in all firewall requests alongside the Primary/Secondary IP address.
• Time Zone and Hardware Configurations (Optional):
  • Recommended but not mandatory for both primary and secondary APM installed machines to be in the same time zone.
  • Having identical hardware is advisable but not strictly required for the primary and secondary APM servers.
• Prerequisites for Linux build: In Linux, the addition of a Virtual IP Address requires SUDO permission. Follow the steps given below in both the primary and secondary servers.
  1. Edit the sudo configuration file using the command:

     sudo visudo

  2. Add the following line to the end of the file:

     <USERNAME> ALL= NOPASSWD:/usr/sbin/ip

     Here, <USERNAME> refers to the username of the machine.
     For example:
     

  Note: The above steps are not required if the setup has been installed with ROOT user privilege. Ensure to implement the prerequisites correctly, or else the setup might not start/stop properly.

Configure Virtual IP address for Failover

1. To configure the Virtual IP address for Failover in Applications Manager go to Settings → Server Settings → High Availability Settings.
2. Fill in the following details to associate Virtual IP for the Failover option:
   • Virtual IP address: The IP address that does not belong to a physical network interface. The IP and the Virtual IP addresses of both servers must belong to the same subnet.
   • Virtual Hostname (optional): The hostname of the Virtual IP address. The hostname must recognize the corresponding Virtual IP address and vice versa.
   • Retry Count: The number of failed association attempts that must be made before initiating the failover mode.
   • Retry Interval in secs: Time interval required to reattempt connecting to the associated Virtual IP address.
3. Next, follow the steps mentioned below for the changes to take effect:
   • Stop the backup / secondary server first (if running). Next, stop the primary server.
   • Now start the primary server. Once it's up and running, proceed to start the secondary server.
   • Once the product has been started successfully it can be accessed via https://<vip>:<port>.