What if every host goes down

+table sorry_server {
+       check icmp
+       host 127.0.0.1
+}
+
 service www {
         virtual host $public_addr port http interface trunk0
         table webhosts
+       backup table sorry_server
 }

result in hoststatectl's output:

Type      Id    Name                            Avlblty Status
service    0    www                                     active (using backup table)
table      0    webhosts                                empty
host       1    10.1.1.101                      0.00%   down
host       0    10.1.1.100                      0.00%   down
table      2    sorry_server:80                         active (1 hosts up)
host       3    127.0.0.1                       100.00% up

Bringing things down

Forcible disabling of hosts is useful for maintenance updates

# hoststatectl table disable webhosts:80 
command succeeded
# hoststatectl show su                   
Type      Id    Name                            Avlblty Status
service    0    www                                     active (using backup table)
table      2    webhosts:80                             disabled
table      3    sorry_server:80                         active (1 hosts up)
host       5    127.0.0.1                       100.00% up

Layer 7 Features

• Generic TCP relaying.
• HTTP/HTTPS relaying.
• DNS relaying.

Generic UDP relaying can not be achieved due to the stateless datagram based nature of the protocol.

Sample HTTPS Relaying configuration

ext_addr="172.16.1.1"
webhost1="10.1.1.100"
webhost2="10.1.1.101"

table webhosts {
        check http "/" code 200
        host $webhost1
        host $webhost2
}

protocol http {
        protocol http
        header append "$REMOTE_ADDR" to "X-Forwarded-For"
        header append "$SERVER_ADDR:$SERVER_PORT" to "X-Forwarded-By"
        header change "Connection" to "close"
}

relay wwwssl {
        listen on $ext_addr port http
        protocol http

        table webhosts loadbalance
}

Relaying methods

• Fixed forwarding.
• Table forwarding, with either roundrobin, loadbalance or hash method.
• Service: use address of specified service.