How to configure IP addresses for IP Pools?

[bakgaard]

According to the documentation, I must setup my server to handle extra IPs I want to use in my IP Pools.

What does this mean?

I take I have to do something like adding it to /etc/network/interfaces, but I have absolutely no idea what I need to do about it.
I am running Postal through docker-compose which might only make this a bit more tricky.

Quick note for the following - I have external IPs, and I have an internal IP.
My external IP1 and IP2 will for this example be 123.123.123.1 and 123.123.123.2.
My internal IP will be 10.10.10.1.

When you hit postal.mysite.com you actually hit 123.123.123.1, and it will forward you to 10.10.10.1.
From here Nginx will send you into my container.
I have setup 123.123.123.2 to also forward to 10.10.10.1

I would like to add 123.123.123.2 to my IP Pool - what do I do?

If I run the command ifconfig on my host, I get something like this:

br-50e152d57bed: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.22.0.1  netmask 255.255.0.0  broadcast 172.22.255.255

docker0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 172.17.0.1  netmask 255.255.0.0  broadcast 172.17.255.255

ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.10.10.1  netmask 255.255.255.0  broadcast 10.10.10.255

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
...

[willpower232]

The IP addresses will need to come from your server provider. They will usually have instructions for how to configure them as they will have specific network settings. You should ask them first.

[creative-andrew]

I am using Contabo as my VPS ( I am not affiliated with them and I don't endorse them), but they have "great" documentation (or least beginner-friendly ) regarding setting up extra IPs.

https://contabo.com/blog/configuring-additional-ip-addresses/

[TuguldurJ]

Add interface like this:

auto eth0:0
iface eth0:0 inet static
        address IP_address
        netmask 255.255.255.255
        post-up /sbin/ifconfig eth0:0 IP_address netmask 255.255.255.255 broadcast IP_address
        pre-down /sbin/ifconfig eth0:0 down