Freeswitch HA mode based on Keepalived.

Idea to have 2 instances of Freeswitch in Master-Slave mode, if one node dies, second will automatically takeover calls with 2-3 seconds lag. Yep, media would be restored.

Main scheme is looks like this

We need 3 IP's. 2 for nodes and 1 for floating.

Solution based on this, but with a bit of additional config.
Used Debian 8x64 as a host OS.
Assume, that we have FreeSWITCH'es already installed.

Install keepalived on both nodes.

apt-get install keepalived

Create files on both nodes

/etc/keepalived/keepalived.conf

global_defs {
    router_id FREESW
}

vrrp_script chk_fs {
    script "/etc/keepalived/scripts/ka-status.pl"
    interval 1
}

vrrp_instance VI_FREESW {
    # replace with SLAVE on a slave node
    state MASTER
    # change to SLAVE on slave node
    interface <YOUR_INTERFACE_HERE>
    #interface eth0
    virtual_router_id <YOUR_ROUTER_ID>
    # virtual_router_id 15
    # higher is preferred for master
    # disable to have failover be sticky
    priority 1
    advert_int 1
    unicast_src_ip <CURRENT_NODE_IP>
    #unicast_src_ip 192.168.10.10
    unicast_peer {
        <SLAVE_NODE_IP>
        #192.168.10.11
    }
    authentication {
        auth_type PASS
        auth_pass YourPassHere
    }
    notify "/etc/keepalived/scripts/ka-notify.pl"
    virtual_ipaddress {
        <FLOATING_IP/CIDR> dev <YOUR_INTERFACE_HERE>
       # 192.168.0.15/24 dev eth0 - Example
    }
    track_script {
        chk_fs
    }
}

/etc/keepalived/scripts/ka-notify.pl
#!/usr/bin/perl

# INSTANCE|VI_FREESW|BACKUP|50
my ($what,$id,$state,$prio) = @ARGV;
open(STDOUT, "|/usr/bin/logger -t ka-notify");

print "what($what) id($id) state($state) prio($prio)\n";

if ( $state eq "MASTER" )
{
    print "Instance went to master, issuing sofia recover.\n";
    system("/usr/bin/fs_cli", "-x", "sofia recover");
}


/etc/keepalived/scripts/ka-status.pl
#!/usr/bin/perl

use Sys::Syslog;
openlog "ka-status", "ndelay,pid", "local0";

my @required = ("internal", "external");

my %saw = ();
open(my $in, "-|") || exec("/usr/bin/fs_cli", "-x", "sofia xmlstatus");
while ( defined(my $line = <$in>) )
{
    if ( $line =~ m|<name>(.*)</name>|o )
    {
        $saw{$1} = 1;
    }
}
close($in);

foreach my $profile ( @required )
{
    if ( ! $saw{$profile} )
    {
        syslog(LOG_INFO, "sip profile $profile not found, marking failure");
        exit(1);
    }
}
exit(0);


chmod +x /etc/keepalived/scripts/*.pl
echo "net.ipv4.ip_nonlocal_bind = 1" >>  /etc/sysctl.conf 

Make sure, that FreeSWITCH'es uses same runtime database and uses same hostname in switch.conf Also profiles you control, need to listen on FLOATING_IP address.
Better reboot here.

service keepalived start

To check state, best is to use ip addr show. On which node FLOATING_IP address is, this is master :)

You can play with priority parameter in keepalived.conf file to make one node Master at all cases.
Point, there is a issue, when you restore calls on one node, you can't get same calls back with sofia recover.