I am in the process of spinning up a new home lab, and I have a need for several Linux-based applications. Since I do not have a plethora of resources (and since I want to try something new), I plan to use containers. What better way to get started than with LXC!

What is LXC? LXC (short for Linux Containers) is an operating system level virtualization method for running multiple isolated Linux containers that share a single Linux kernel. There is a good read here which explains the features and components of LXC.

In order to provide connectivity to my containers, I need to first create a network bridge. There are two main types of bridges that can be used for connectivity: a Host Bridge and an Independent Bridge (aka masqueraded bridge). I won’t go into detail as to the differences between the two. For the purposes of my lab I’ll be using a Host Bridge, which allow my containers to connect directly to the host network.

There are plenty of great articles to create Linux bridges. For mine, I made a copy my current ifcfg-eth0 script with some minor edits:

cat /etc/sysconfig/network-interfaces/ifcfg-eth0
TYPE="Ethernet"
NAME="eth0"
DEVICE="eth0"
ONBOOT="yes"
BRIDGE="br0"

Note: The BRIDGE=”br0″ parameter sets what my physical eth0 interface is bound to.

cat /etc/sysconfig/network-interfaces/ifcfg-br0
DEVICE="br0"
ONBOOT="yes"
TYPE="Bridge"
BOOTPROTO="static"
IPADDR="192.168.133.129"
PREFIX="24"
GATEWAY="192.168.133.1"
DNS1="192.168.133.1"
STP="on"
DELAY="0"

Initialize the bridge by restarting the network:

service network restart
brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.000g69ae8810       yes             eth0

Now on to installing LXC:

yum install epel-release
yum install debootstrap perl libvirt
yum install lxc lxc-templates
yum install lxc-extra-1.0.11-2.el7.x86_64

Once installed, I start and enable the services for startup:

systemctl start lxc.service
systemctl start libvirtd 
systemctl enable lxc.service
systemctl enable libvirtd

Give the configuration a quick check with lxc-checkconfig:

Kernel configuration not found at /proc/config.gz; searching...
Kernel configuration found at /boot/config-3.10.0-1127.8.2.el7.x86_64
--- Namespaces ---
Namespaces: enabled
Utsname namespace: enabled
Ipc namespace: enabled
Pid namespace: enabled
User namespace: enabled
Warning: newuidmap is not setuid-root
Warning: newgidmap is not setuid-root
Network namespace: enabled
Multiple /dev/pts instances: enabled

--- Control groups ---
Cgroup: enabled
Cgroup clone_children flag: enabled
Cgroup device: enabled
Cgroup sched: enabled
Cgroup cpu account: enabled
Cgroup memory controller: enabled
Cgroup cpuset: enabled

--- Misc ---
Veth pair device: enabled
Macvlan: enabled
Vlan: enabled
Bridges: enabled
Advanced netfilter: enabled
CONFIG_NF_NAT_IPV4: enabled
CONFIG_NF_NAT_IPV6: enabled
CONFIG_IP_NF_TARGET_MASQUERADE: enabled
CONFIG_IP6_NF_TARGET_MASQUERADE: enabled
CONFIG_NETFILTER_XT_TARGET_CHECKSUM: enabled

--- Checkpoint/Restore ---
checkpoint restore: enabled
CONFIG_FHANDLE: enabled
CONFIG_EVENTFD: enabled
CONFIG_EPOLL: enabled
CONFIG_UNIX_DIAG: enabled
CONFIG_INET_DIAG: enabled
CONFIG_PACKET_DIAG: enabled
CONFIG_NETLINK_DIAG: enabled
File capabilities: enabled

Looking good! Now I can configure LXC to use the newly created Host Bridge. Edit /etc/lxc/default.conf and change lxc.network.link to br0.

lxc.network.type = veth
lxc.network.link = br0
lxc.network.flags = up

Now we can move on to creating our first container!

lxc-create -n centos01 -t centos

Start the container:

lxc-start -n centos01  

And check the status:

[root@lnx01 ~]# lxc-info -n centos01
Name:           centos01
State:          RUNNING
PID:            1772
IP:             192.168.133.134
CPU use:        0.13 seconds
BlkIO use:      0 bytes
Memory use:     1.04 MiB
KMem use:       0 bytes
Link:           vethN4UYM8
 TX bytes:      1.39 KiB
 RX bytes:      1.87 KiB
 Total bytes:   3.26 KiB

And there we have it! LXC is up, and our test CentOS container is running on our host system.