How to switch the IP address to the second server if the first one is unavailable if they are in different DCs?

Question

High availability

Hello! There are two servers in different DCs of different hosting providers (one physical, the second VPS). OS on both Debian. Is it possible to somehow switch the IP address so that it leads to the second server when the first one is unavailable?

Answer 1

Quite understandable. A person needs automatic switching between servers for their constant availability.
And so, the options are:
1. Understand what DM-VPN is
2. Set up a regular VPN Site-to-Site and google in the direction of OSPF and its settings.
3. Google towards IP SLA. By the way, this option can easily be made a banal bat-nickname or bash.
4. Google towards DDNS.
5. Spend a few thousand dollars and set up BGP :)
The only clarification. Should the servers be available from some third place and only from it, or from somewhere outside? I mean, will employees of one office or several will use the service on the servers? Or even third-party clients of the company?

Answer 2

And there is a terrible way, which, nevertheless, is successfully used by Content Delivery Networks - all these video hostings of yours.
The idea is to give the same IP address from different DCs via BGP.
Thus, the time of full guaranteed restoration of the service is approximately equal to the time of BGP convergence. This usually happens faster than fading entries in the caches of DNS servers.
Behind this address in both DCs, by the way, it is quite possible to hide balancers that are connected to both DCs, and scatter the services hidden behind the balancers across gray networks allocated for specific DCs.

Answer 3

It's not quite clear what "switch" means? to assign ip of one server to the second one?