Backup routing - Githubissues

yyyar / gobetween

:cloud: Modern & minimalistic load balancer for the Сloud era

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Backup routing #62

Open nickdoikov opened 7 years ago

nickdoikov commented 7 years ago

Need to implement backup server functionality. When all backends for server failed - use separate single host for backup connections. This will dramatically increase redundancy in big geo distributed infrastructures.

yyyar commented 7 years ago

http://blog.haproxy.com/2013/12/23/failover-and-worst-case-management-with-haproxy/

nickdoikov commented 7 years ago

backup is not a backend but more is a routing on disaster logic. we need use multiple backup hosts in list sequentially, not in parallel. because list of backup servers in most cases will be point to server frontend of different gobetween in nearest geo location , second backup farest away from first and so on.

illarion commented 7 years ago

Proposed config and simple rules:

[servers.sample]
...
[servers.sample.backup]
healthcheck_min_backends = 2
servers_list = [
     "foo.bar:8000",
     "foo.bar.cn:8000"
]

Backup will depend on configured healthchecks and gobetween will not start if it is not configured, but backup is specified.
Backup will be used only if all backends have failed healthchecks
Backup servers will be checked using same healthcheck mechanism as backends
Backup servers healthcheck will be turned on if there's less or equal than healthcheck_min_backends backends left alive
Only one backup server will be used -- first that have passed healthcheck

nickdoikov commented 7 years ago

Only one backup server will be used -- first that have passed healthcheck mechanism should not be dependable to health checks possible race conditions.

i think we should made a check optional for backup servers and not dependable to server checks (separate on/of for the backup sedvers)

[servers.sample]
...
[servers.sample.backup]
healthcheck_min_backends = 2
healthcheck_enable=true|false
servers_list = [
     "foo.bar:8000",
     "foo.bar.cn:8000"
]

illarion commented 7 years ago

What will happen if there's more than one backup server with heatlhchecks turned off, and first of them fails? How should gobetween decide to route traffic to the second one?

nickdoikov commented 7 years ago

need to take first one. rest other will be ignored .

illarion commented 7 years ago

[servers.sample]
...
[servers.sample.backup]
servers_list = [
    "foo.bar:8000",
    "foo.bar.cn:8000"
]

[servers.sample.backup.healthcheck]
enabled=true|false
min_backends = 2
#other options similar to usual backend healthcheck

praveenkumar2608 commented 4 years ago

This feature would be very helpful if it gets implemented.

illarion commented 4 years ago

I am planning to implement this using weight + priority and some additional configuration