Demonstration 2

Purpose

Demonstration 2 builds on the single step test sequence from the previous demo:

1. We'll run the test on two LXC containers instead of the local host. To do so, we'll introduce etce-lxc and the ETCE LXC Plan File for creating networks of LXC containers and Linux bridges.

2. Many Wrappers expose configuration parameters that can be conveniently set at run time. We'll use etce-wrapper to look at the utils.hello parameters and show how to set their values in steps.xml or with a separate ETCE Configuration File.

Activity 1 - Launch The Network

ETCE executes applications on test hosts over SSH. No matter whether the hosts are real, virtual, local or remote, if ETCE can connect to the target user account via public key authentication, it can use the host in tests.

While ETCE was initially developed on a rack of physical servers, the more recent evolution of multi-CPU systems means that ETCE can orchestrate relatively complex EMANE emulations of several dozen nodes, even on a single machine. Obviously virtualization is the key to this, and light-weight LXC containers are a favorite option.

etce-lxc eases the task of setting up LXC networks. Given a self-contained LXC Plan File, etce-lxc:

* Generates LXC version appropriate lxc.container.conf style
  configuration files from templates for multiple containers,
  optionally situated on multiple physical hosts.
* Generates an init script run by the containers on startup.
  For ETCE, this invariably means starting an `sshd` instance.
* Creates operating directories for each container in the
  ETCE Working Directory (under `lxcroot`).
* Runs `lxc-execute` to start the containers and creates
  the Linux Bridges to interconnect them. Bridges are
  named in the Plan File, explicity or implicitly
* Optionally populates /etc/hosts with Plan File marked interface
  addresses and host names.

Demonstration 2 is contained in the 02.hello_lxc subdirectory. The LXC Plan File for the demo is 02.hello_lxc/doc/lxcplan.xml:

<lxcplan>
  <hosts>
    <host hostname="localhost">
      <bridges>
        <bridge name="br.ctl" persistent="false">
          <ipaddress>
            <ipv4>10.76.0.200/24</ipv4>
          </ipaddress>
        </bridge>
      </bridges>

      <containers>
        <container lxc_name="node-${'%03d' % lxc_index}" lxc_indices="1-2">
          <parameters>
            <parameter name="lxc.console" value="none"/>
            <parameter name="lxc.tty" value="1"/>
            <parameter name="lxc.pts" value="128"/>
          </parameters>
          <interfaces>
            <interface bridge="br.ctl">
              <parameter name="lxc.network.type" value="veth"/>
              <parameter name="lxc.network.name" value="backchan0"/>
              <parameter name="lxc.network.flags" value="up"/>
              <parameter name="lxc.network.hwaddr" value="02:00:${'%02x' % lxc_index}:01:00:${'%02x' % lxc_index}"/>
              <parameter name="lxc.network.ipv4" value="10.76.0.${lxc_index}/16"/>
              <parameter name="lxc.network.veth.pair" value="veth.ctl.${lxc_index}"/>
            </interface>
          </interfaces>
          <initscript>#!/bin/bash

# make node for tun device
mkdir /dev/net
mknod /dev/net/tun c 10 200

pidfile="${lxc_directory}/var/run/sshd.pid"
/usr/sbin/sshd -o "PidFile=$pidfile" -o "PermitRootLogin=yes" -o "PasswordAuthentication=no"
          </initscript>
        </container>
      </containers>
    </host>
  </hosts>
</lxcplan>

The hosts element contains one or more host children. Each host corresponds to an available compute resource, typically a physical server, that will run the bridges and containers defined underneath.

The bridges section explicitly names Linux Bridges that will be created on the host, along with an optional IP Address.

[etceuser@host]$ ls /tmp/etce/lxcroot
etce.lxc.lock  node-001  node-002
[etceuser@host]$ tree /tmp/etce/lxcroot/node-001
/tmp/etce/lxcroot/node-001
|__ config
|__ init.sh
|__ log
|__ mnt
|__ var
    |__ lib
    |__ log
    |__ run
        |__ sshd.pid

[etceuser@host]$ cat /tmp/etce/lxcroot/node-001/config
lxc.utsname=node-001
lxc.console=none
lxc.tty=1
lxc.pts=128

# br.ctl interface
lxc.network.type=veth
lxc.network.flags=up
lxc.network.hwaddr=02:00:01:01:00:01
lxc.network.ipv4=10.76.0.1/16
lxc.network.name=backchan0
lxc.network.veth.pair=veth.ctl.1
lxc.network.link=br.ctl

# loopback interface
lxc.network.type=empty
lxc.network.flags=up

[etceuser@host]$ cat /tmp/etce/lxcroot/node-001/init.sh
#!/bin/bash
# make node for tun device
mkdir /dev/net
mknod /dev/net/tun c 10 200
pidfile="/tmp/etce/lxcroot/node-001/var/run/sshd.pid"
/usr/sbin/sshd -o "PidFile=$pidfile" -o "PermitRootLogin=yes" -o "PasswordAuthentication=no"

Activity 2 - Setting Wrapper Parameters

Activity 3 - Run The Demo

Activity 4 - Examine The Output