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Introduction
By default, your containers are accessible only from the host. For serious use you will want to expose some containers to the outside world. There are various ways of doing this. Currently I have settled on the following,
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Make sure to change the password or better remove the default ubuntu account generated by the lxc creation script before making the container accessible to the Internet. |
Port Forwarding using IP Tables
You might want to use one IP Address on the host and then map specific ports out from the containers. As a pre-requisite you will need to setup Static LXC Assigned IP address.
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sudo iptables -t nat -D PREROUTING -p tcp -i eth0 --dport 22 -j DNAT --to-destination 10.0.3.11:23 |
macvlan with Additional IP
For further isolation you may have purchased an additional IP address. In most hosting services this is not expensive, but they will likely not give you a dedicated network card. In this example we purchase an additional static IP from the hosting company and use the same network card as the host.
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- 1 macvlan mapped to 1 container interface
- each interface must have different static IP addresses
macvlan mac address
The first thing to do is to create a mac address for the macvlan interface we will create on the host.
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You can not use the same MAC interface on multiple containers on the same host. Otherwise, you will not be able to start you container and receive the error message about your interface already being in use. |
Command Line macvlan
You can use the command line inside your container to quickly create a macvlan and test, but it will disappear after reboot,
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ip link add mvlan0 link eth0 address 8a:38:2a:cc:d7:aa type macvlan mode bridge ifconfig mvlan0 up |
Create a Permanent macvlan on the Host
Add to the bottom of the /etc/network/interfaces file of the host,
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Notice mvlan0 is present with the hardware address you specified.
Connect Container to macvlan on Host
Now one container may connect to the mvlan0 interface on the host and they will get their IPs directly from the same network connected to the host (if DHCP) or you can assign static IPs inside the container that are reserved for you.
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Above we now have two interfaces. The static interface is the public IP address purchased called eth0 and second is the internal LXC assigned address. The other entries can be obtained from Add Additional IP Addresses to Ubuntu Server.
Update dnsmasq
Make sure to check your dnsmasq and make modifications accordingly. Using the example since we modified a container that was already using dnsmasq we needed to change the original /etc/lxc/dnsmasq.conf,
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Multiple Interfaces
In most cases you will want multiple interfaces. In this example, we built a front-end container called "web", gave it a public IP address using mavlan. In addition, we create an "app" container which has an lxc internal IP address. In order for web and app to communicate, web must have a second interface that also uses an lxc provided internal IP address.
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I got this all working, but need to document.
macvtap
This looks promising... The most prominent user of macvtap interfaces seems to be libvirt/KVM, which allows guests to be connected to macvtap interfaces. Doing so allows for (almost) bridged-like behaviour of guests but without the need to have a real bridge on the host, as a regular ethernet interface can be used as the macvtap's lower device.
References
Networking - https://help.ubuntu.com/lts/serverguide/lxc.html#lxc-network
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