T4904: keepalived virtual-server allow multiple ports with fwmark

[sever-sever]

Allow multiple ports for high-availability virtual-server The current implementation allows balance only one "virtual" address and port between several "real servers"
Allow matching "fwmark" to set traffic which should be balanced.

Allow setting port 0 (all traffic) if we use "fwmark" Add health-check script.

Change Summary

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://phabricator.vyos.net/T4904

Component(s) name

keepalive, virtual-server

Proposed changes

How to test

We can mark just required ports without IP addresses or with them
And use fwmark value for virtual-server
Also, we use "port 0" as we mark several ports

VyOS config:

set interfaces ethernet eth0 address '192.0.2.1/24'
set interfaces ethernet eth0 description 'LAN'
set interfaces ethernet eth4 address 'dhcp'
set interfaces ethernet eth4 description 'WAN'

set policy route PR interface 'eth4'
set policy route PR rule 10 destination port '80,2222,8888'
set policy route PR rule 10 protocol 'tcp'
set policy route PR rule 10 set mark '111'

set high-availability virtual-server 203.0.113.1 fwmark '111'
set high-availability virtual-server 203.0.113.1 protocol 'tcp'
set high-availability virtual-server 203.0.113.1 real-server 192.0.2.11 health-check script '/bin/true'
set high-availability virtual-server 203.0.113.1 real-server 192.0.2.11 port '0'
set high-availability virtual-server 203.0.113.1 real-server 192.0.2.12 health-check script '/bin/true'
set high-availability virtual-server 203.0.113.1 real-server 192.0.2.12 port '0'

set nat source rule 100 outbound-interface 'eth4'
set nat source rule 100 source address '192.0.2.0/24'
set nat source rule 100 translation address 'masquerade'

Keepal;lived config

vyos@r1# cat /run/keepalived/keepalived.conf 
...
# Virtual-server configuration
# Vserver 203.0.113.1
virtual_server fwmark 111 {
    delay_loop 10
    lb_algo lc
    lb_kind NAT
    persistence_timeout 300
    protocol TCP
    real_server 192.0.2.11 0 {
        weight 1
        MISC_CHECK {
            misc_path /bin/true
        }
    }
    real_server 192.0.2.12 0 {
        weight 1
        MISC_CHECK {
            misc_path /bin/true
        }
    }
}

Show virtual-server

vyos@r1# run show virtual-server 
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
FWM  111 lc persistent 300
  -> 192.0.2.11:0                 Masq    1      0          0         
  -> 192.0.2.12:0                 Masq    1      1          0
[edit]
vyos@r1# 

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly