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<div class="document">
<div class="section" id="testbox-imaging-backup-restore">
<h1>Testbox Imaging (Backup / Restore)</h1>
<div class="section" id="introduction">
<h2>Introduction</h2>
<p>This document is explores deploying a very simple drive imaging solution to help
avoid needing to manually reinstall testboxes when a disk goes bust or the OS
install seems to be corrupted.</p>
</div>
</div>
<div class="section" id="definitions-glossary">
<h1>Definitions / Glossary</h1>
<p>See AutomaticTestingRevamp.txt.</p>
</div>
<div class="section" id="objectives">
<h1>Objectives</h1>
<blockquote>
<ul class="simple">
<li>Off site, no admin interaction (no need for ILOM or similar).</li>
<li>OS independent.</li>
<li>Space and bandwidth efficient.</li>
<li>As automatic as possible.</li>
<li>Logging.</li>
</ul>
</blockquote>
</div>
<div class="section" id="overview-of-the-solution">
<h1>Overview of the Solution</h1>
<p>Here is a brief summary:</p>
<blockquote>
<ul class="simple">
<li>Always boot testboxes via PXE using PXELINUX.</li>
<li>Default configuration is local boot (hard disk / SSD)</li>
<li>Restore/backup action triggered by machine specific PXE config.</li>
<li>Boots special debian maintenance install off NFS.</li>
<li>A maintenance service (systemd style) does the work.</li>
<li>The service reads action from TFTP location and performs it.</li>
<li>When done the service removes the TFTP machine specific config
and reboots the system.</li>
</ul>
</blockquote>
<dl class="docutils">
<dt>Maintenance actions are:</dt>
<dd><ul class="first last simple">
<li>backup</li>
<li>backup-again</li>
<li>restore</li>
<li>refresh-info</li>
<li>rescue</li>
</ul>
</dd>
</dl>
<p>Possible modifier that indicates a subset of disk on testboxes with other OSes
installed. Support for partition level backup/restore is not explored here.</p>
<div class="section" id="how-to-use">
<h2>How to use</h2>
<p>To perform one of the above maintenance actions on a testbox, run the
<tt class="docutils literal"><span class="pre">testbox-pxe-conf.sh</span></tt> script:</p>
<pre class="literal-block">
/mnt/testbox-tftp/pxeclient.cfg/testbox-pxe-conf.sh 10.165.98.220 rescue
</pre>
<p>Then trigger a reboot. The box will then boot the NFS rooted debian image and
execute the maintenance action. On success, it will remove the testbox hex-IP
config file and reboot again.</p>
</div>
</div>
<div class="section" id="storage-server">
<h1>Storage Server</h1>
<p>The storage server will have three areas used here. Using NFS for all three
avoids extra work getting CIFS sharing right too (NFS is already a pain).</p>
<blockquote>
<ol class="arabic simple">
<li>/export/testbox-tftp - TFTP config area. Read-write.</li>
<li>/export/testbox-backup - Images and logs. Read-write.</li>
<li>/export/testbox-nfsroot - Custom debian. Read-only, no root squash.</li>
</ol>
</blockquote>
</div>
<div class="section" id="tftp-export-testbox-tftp">
<h1>TFTP (/export/testbox-tftp)</h1>
<p>The testbox-tftp share needs to be writable, root squashing is okay.</p>
<p>We need files from both PXELINUX and SYSLINUX to make this work now. On a
debian system, the <tt class="docutils literal">pxelinux</tt> and <tt class="docutils literal">syslinux</tt> packages needs to be
installed. We actually do this further down when setting up the nfsroot, so
it's possible to get them from there by postponing this step a little. On
debian 8.6.0 the PXELINUX files are found in <tt class="docutils literal">/usr/lib/PXELINUX</tt> and the
SYSLINUX ones in <tt class="docutils literal">/usr/lib/syslinux</tt>.</p>
<p>The initial PXE image as well as associated modules comes in three variants,
BIOS, 32-bit EFI and 64-bit EFI. We'll only need the BIOS one for now.
Perform the following copy operations:</p>
<pre class="literal-block">
cp /usr/lib/PXELINUX/pxelinux.0 /mnt/testbox-tftp/
cp /usr/lib/syslinux/modules/*/ldlinux.* /mnt/testbox-tftp/
cp -R /usr/lib/syslinux/modules/bios /mnt/testbox-tftp/
cp -R /usr/lib/syslinux/modules/efi32 /mnt/testbox-tftp/
cp -R /usr/lib/syslinux/modules/efi64 /mnt/testbox-tftp/
</pre>
<p>For simplicity, all the testboxes boot using good old fashioned BIOS, no EFI.
However, it doesn't really hurt to be prepared.</p>
<p>The PXELINUX related files goes in the root of the testbox-tftp share. (As
mentioned further down, these can be installed on a debian system by running
<tt class="docutils literal"><span class="pre">apt-get</span> install pxelinux syslinux</tt>.) We need the <tt class="docutils literal">*pxelinux.0</tt> files
typically found in <tt class="docutils literal">/usr/lib/PXELINUX/</tt> on debian systems (recent ones
anyway). It is possible we may need one ore more fo the modules <a class="footnote-reference" href="#footnote-1" id="footnote-reference-1">[1]</a> that
ships with PXELINUX/SYSLINUX, so do copy <tt class="docutils literal">/usr/lib/syslinux/modules</tt> to
<tt class="docutils literal"><span class="pre">testbox-tftp/modules</span></tt> as well.</p>
<p>The directory layout related to the configuration files is dictated by the
PXELINUX configuration file searching algorithm <a class="footnote-reference" href="#footnote-2" id="footnote-reference-2">[2]</a>. Create a subdirectory
<tt class="docutils literal">pxelinux.cfg/</tt> under <tt class="docutils literal"><span class="pre">testbox-tftp</span></tt> and create the world readable file
<tt class="docutils literal">default</tt> with the following content:</p>
<pre class="literal-block">
PATH bios
DEFAULT local-boot
LABEL local-boot
LOCALBOOT
</pre>
<p>This will make the default behavior to boot the local disk system.</p>
<p>Copy the <tt class="docutils literal"><span class="pre">testbox-pxe-conf.sh</span></tt> script file found in the same directory as
this document to <tt class="docutils literal"><span class="pre">/mnt/testbox-tftp/pxelinux.cfg/</span></tt>. Edit the copy to correct
the IP addresses near the top, as well as any linux, TFTP and PXE details near
the bottom of the file. This script will generate the PXE configuration file
when performing maintenance on a testbox.</p>
</div>
<div class="section" id="images-and-logs-export-testbox-backup">
<h1>Images and logs (/export/testbox-backup)</h1>
<p>The testbox-backup share needs to be writable, root squashing is okay.</p>
<p>In the root there must be a file <tt class="docutils literal"><span class="pre">testbox-backup</span></tt> so we can easily tell
whether we've actually mounted the share or are just staring at an empty mount
point directory.</p>
<p>The <tt class="docutils literal"><span class="pre">testbox-maintenance.sh</span></tt> script maintains a global log in the root
directory that's called <tt class="docutils literal">maintenance.log</tt>. Errors will be logged there as
well as a ping and the action.</p>
<p>We use a directory layout based on dotted decimal IP addresses here, so for a
server with the IP 10.40.41.42 all its file will be under <tt class="docutils literal">10.40.41.42/</tt>:</p>
<dl class="docutils">
<dt><tt class="docutils literal"><hostname></tt></dt>
<dd>The name of the testbox (empty file). Help finding a testbox by name.</dd>
<dt><tt class="docutils literal"><span class="pre">testbox-info.txt</span></tt></dt>
<dd>Information about the testbox. Starting off with the name, decimal IP,
PXELINUX style hexadecimal IP, and more.</dd>
<dt><tt class="docutils literal">maintenance.log</tt></dt>
<dd>Maintenance log file recording what the maintenance service does.</dd>
<dt><tt class="docutils literal"><span class="pre">disk-devices.lst</span></tt></dt>
<dd>Optional list of disk devices to consider backuping up or restoring. This is
intended for testboxes with additional disks that are used for other purposes
and should touched.</dd>
<dt><tt class="docutils literal">sda.raw.gz</tt></dt>
<dd>The gzipped raw copy of the sda device of the testbox.</dd>
<dt><tt class="docutils literal"><span class="pre">sd[bcdefgh].raw.gz</span></tt></dt>
<dd>The gzipped raw copy sdb, sdc, sde, sdf, sdg, sdh, etc if any of them exists
and are disks/SSDs.</dd>
<dt>Note! If it turns out we can be certain to get a valid host name, we might just</dt>
<dd>switch to use the hostname as the directory name instead of the IP.</dd>
</dl>
</div>
<div class="section" id="debian-nfs-root-export-testbox-nfsroot">
<h1>Debian NFS root (/export/testbox-nfsroot)</h1>
<p>The testbox-nfsroot share should be read-only and must <strong>not</strong> have root
squashing enabled. Also, make sure setting the set-uid-bit is allowed by the
server, or <tt class="docutils literal">su` and ``sudo</tt> won't work</p>
<p>There are several ways of creating a debian nfsroot, but since we've got a
tool like VirtualBox around we've just installed it in a VM, prepared it,
and copied it onto the NFS server share.</p>
<p>As of writing debian 8.6.0 is current, so a minimal 64-bit install of it was
done in a VM. After installation the following modifications was done:</p>
<blockquote>
<ul>
<li><p class="first"><tt class="docutils literal"><span class="pre">apt-get</span> install pxelinux syslinux <span class="pre">initramfs-tools</span> zip gddrescue sudo joe</tt>
and optionally <tt class="docutils literal"><span class="pre">apt-get</span> install smbclient <span class="pre">cifs-utils</span></tt>.</p>
</li>
<li><p class="first"><tt class="docutils literal">/etc/default/grub</tt> was modified to set <tt class="docutils literal">GRUB_CMDLINE_LINUX_DEFAULT</tt> to
<tt class="docutils literal">""</tt> instead of <tt class="docutils literal">"quiet"</tt>. This allows us to see messages during boot
and perhaps spot why something doesn't work on a testbox. Regenerate the
grub configuration file by running <tt class="docutils literal"><span class="pre">update-grub</span></tt> afterwards.</p>
</li>
<li><p class="first"><tt class="docutils literal">/etc/sudoers</tt> was modified to allow the <tt class="docutils literal">vbox</tt> user use sudo without
requring any password.</p>
</li>
<li><p class="first">Create the directory <tt class="docutils literal">/etc/systemd/system/getty@tty1.service.d</tt> and create
the file <tt class="docutils literal">noclear.conf</tt> in it with the following content:</p>
<pre class="literal-block">
[Service]
TTYVTDisallocate=no
</pre>
<p>This stops getty from clearing VT1 and let us see the tail of the boot up
messages, which includes messages from the testbox-maintenance service.</p>
</li>
<li><p class="first">Mount the testbox-nfsroot under <tt class="docutils literal">/mnt/</tt> with write privileges. (The write
privileges are temporary - don't forget to remove them later on.):</p>
<pre class="literal-block">
mount -t nfs myserver.com:/export/testbox-nfsroot
</pre>
<p>Note! Adding <tt class="docutils literal"><span class="pre">-o</span> nfsvers=3</tt> may help with some NTFv4 servers.</p>
</li>
<li><p class="first">Copy the debian root and dev file system onto nfsroot. If you have ssh
access to the NFS server, the quickest way to do it is to use <tt class="docutils literal">tar</tt>:</p>
<pre class="literal-block">
tar -cz --one-file-system -f /mnt/testbox-maintenance-nfsroot.tar.gz . dev/
</pre>
<p>An alternative is <tt class="docutils literal">cp <span class="pre">-ax</span> . /mnt/. && cp <span class="pre">-ax</span> dev/. /mnt/dev/.</tt> but this
is quite a bit slower, obviously.</p>
</li>
<li><p class="first">Edit <tt class="docutils literal">/etc/ssh/sshd_config</tt> setting <tt class="docutils literal">PermitRootLogin</tt> to <tt class="docutils literal">yes</tt> so we can ssh
in as root later on.</p>
</li>
<li><p class="first">chroot into the nfsroot: <tt class="docutils literal">chroot /mnt/</tt></p>
<blockquote>
<ul>
<li><p class="first"><tt class="docutils literal">mount <span class="pre">-o</span> proc proc /proc</tt></p>
</li>
<li><p class="first"><tt class="docutils literal">mount <span class="pre">-o</span> sysfs sysfs /sys</tt></p>
</li>
<li><p class="first"><tt class="docutils literal">mkdir <span class="pre">/mnt/testbox-tftp</span> <span class="pre">/mnt/testbox-backup</span></tt></p>
</li>
<li><p class="first">Recreate <tt class="docutils literal">/etc/fstab</tt> with:</p>
<pre class="literal-block">
proc /proc proc defaults 0 0
/dev/nfs / nfs defaults 1 1
10.42.1.1:/export/testbox-tftp /mnt/testbox-tftp nfs tcp,nfsvers=3,noauto 2 2
10.42.1.1:/export/testbox-backup /mnt/testbox-backup nfs tcp,nfsvers=3,noauto 3 3
</pre>
<p>We use NFS version 3 as that works better for our NFS server and client,
remove if not necessary. The <tt class="docutils literal">noauto</tt> option is to work around mount
trouble during early bootup on some of our boxes.</p>
</li>
<li><p class="first">Do <tt class="docutils literal">mount <span class="pre">/mnt/testbox-tftp</span> && mount <span class="pre">/mnt/testbox-backup</span></tt> to mount the
two shares. This may be a good time to execute the instructions in the
sections above relating to these two shares.</p>
</li>
<li><p class="first">Edit <tt class="docutils literal"><span class="pre">/etc/initramfs-tools/initramfs.conf</span></tt> and change the <tt class="docutils literal">MODULES</tt>
value from <tt class="docutils literal">most</tt> to <tt class="docutils literal">netboot</tt>.</p>
</li>
<li><p class="first">Append <tt class="docutils literal">aufs</tt> to <tt class="docutils literal"><span class="pre">/etc/initramfs-tools/modules</span></tt>. The advanced
multi-layered unification filesystem (aufs) enables us to use a
read-only NFS root. <a class="footnote-reference" href="#footnote-3" id="footnote-reference-3">[3]</a> <a class="footnote-reference" href="#footnote-4" id="footnote-reference-4">[4]</a> <a class="footnote-reference" href="#footnote-5" id="footnote-reference-5">[5]</a></p>
</li>
<li><p class="first">Create <tt class="docutils literal"><span class="pre">/etc/initramfs-tools/scripts/init-bottom/00_aufs_init</span></tt> as
an executable file with the following content:</p>
<pre class="literal-block">
#!/bin/sh
# Don't run during update-initramfs:
case "$1" in
prereqs)
exit 0;
;;
esac
modprobe aufs
mkdir -p /ro /rw /aufs
mount -t tmpfs tmpfs /rw -o noatime,mode=0755
mount --move $rootmnt /ro
mount -t aufs aufs /aufs -o noatime,dirs=/rw:/ro=ro
mkdir -p /aufs/rw /aufs/ro
mount --move /ro /aufs/ro
mount --move /rw /aufs/rw
mount --move /aufs /root
exit 0
</pre>
</li>
<li><p class="first">Update the init ramdisk: <tt class="docutils literal"><span class="pre">update-initramfs</span> <span class="pre">-u</span> <span class="pre">-k</span> all</tt></p>
<dl class="docutils">
<dt>Note! It may be necessary to do <tt class="docutils literal">mount <span class="pre">-t</span> tmpfs tmpfs /var/tmp</tt> to help</dt>
<dd><p class="first last">this operation succeed.</p>
</dd>
</dl>
</li>
<li><p class="first">Copy <tt class="docutils literal">/boot</tt> to <tt class="docutils literal"><span class="pre">/mnt/testbox-tftp/maintenance-boot/</span></tt>.</p>
</li>
<li><p class="first">Copy the <tt class="docutils literal"><span class="pre">testbox-maintenance.sh</span></tt> file found in the same directory as this
document to <tt class="docutils literal">/root/scripts/</tt> (need to create the dir) and make it
executable.</p>
</li>
<li><p class="first">Create the systemd service file for the maintenance service as
<tt class="docutils literal"><span class="pre">/etc/systemd/system/testbox-maintenance.service</span></tt> with the content:</p>
<pre class="literal-block">
[Unit]
Description=Testbox Maintenance
After=network.target
Before=getty@tty1.service
[Service]
Type=oneshot
RemainAfterExit=True
ExecStart=/root/scripts/testbox-maintenance.sh
ExecStartPre=/bin/echo -e \033%G
ExecReload=/bin/kill -HUP $MAINPID
WorkingDirectory=/tmp
Environment=TERM=xterm
StandardOutput=journal+console
[Install]
WantedBy=multi-user.target
</pre>
</li>
<li><p class="first">Enable our service: <tt class="docutils literal">systemctl enable <span class="pre">/etc/systemd/system/testbox-maintenance.service</span></tt></p>
</li>
<li><p class="first">xxxx ... more ???</p>
</li>
<li><p class="first">Before leaving the chroot, do <tt class="docutils literal">mount /proc /sys <span class="pre">/mnt/testbox-*</span></tt>.</p>
</li>
</ul>
</blockquote>
</li>
<li><p class="first">Testing the setup from a VM is kind of useful (if the nfs server can be
convinced to accept root nfs mounts from non-privileged clinet ports):</p>
<blockquote>
<ul>
<li><p class="first">Create a VM using the 64-bit debian profile. Let's call it "pxe-vm".</p>
</li>
<li><p class="first">Mount the TFTP share somewhere, like M: or /mnt/testbox-tftp.</p>
</li>
<li><p class="first">Reconfigure the NAT DHCP and TFTP bits:</p>
<pre class="literal-block">
VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/AboveDriver NAT
VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/Action mergeconfig
VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/Config/TFTPPrefix M:/
VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/Config/BootFile pxelinux.0
</pre>
</li>
<li><p class="first">Create the file <tt class="docutils literal"><span class="pre">testbox-tftp/pxelinux.cfg/0A00020F</span></tt> containing:</p>
<pre class="literal-block">
PATH bios
DEFAULT maintenance
LABEL maintenance
MENU LABEL Maintenance (NFS)
KERNEL maintenance-boot/vmlinuz-3.16.0-4-amd64
APPEND initrd=maintenance-boot/initrd.img-3.16.0-4-amd64 ro ip=dhcp aufs=tmpfs \
boot=nfs root=/dev/nfs nfsroot=10.42.1.1:/export/testbox-nfsroot
LABEL local-boot
LOCALBOOT
</pre>
</li>
</ul>
</blockquote>
</li>
</ul>
</blockquote>
</div>
<div class="section" id="troubleshooting">
<h1>Troubleshooting</h1>
<dl class="docutils">
<dt><tt class="docutils literal"><span class="pre">PXE-E11</span></tt> or something like <tt class="docutils literal">No ARP reply</tt></dt>
<dd>You probably got the TFTP and DHCP on different machines. Try move the TFTP
to the same machine as the DHCP, then the PXE stack won't have to do any
additional ARP resolving. Google results suggest that a congested network
could use the ARP reply to get lost. Our suspicion is that it might also be
related to the PXE stack shipping with the NIC.</dd>
</dl>
<hr class="docutils" />
<table class="docutils footnote" frame="void" id="footnote-1" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-1">[1]</a></td><td>See <a class="reference external" href="http://www.syslinux.org/wiki/index.php?title=Category:Modules">http://www.syslinux.org/wiki/index.php?title=Category:Modules</a></td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="footnote-2" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-2">[2]</a></td><td>See <a class="reference external" href="http://www.syslinux.org/wiki/index.php?title=PXELINUX#Configuration">http://www.syslinux.org/wiki/index.php?title=PXELINUX#Configuration</a></td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="footnote-3" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-3">[3]</a></td><td>See <a class="reference external" href="https://en.wikipedia.org/wiki/Aufs">https://en.wikipedia.org/wiki/Aufs</a></td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="footnote-4" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-4">[4]</a></td><td>See <a class="reference external" href="http://shitwefoundout.com/wiki/Diskless_ubuntu">http://shitwefoundout.com/wiki/Diskless_ubuntu</a></td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="footnote-5" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-5">[5]</a></td><td>See <a class="reference external" href="http://debianaddict.com/2012/06/19/diskless-debian-linux-booting-via-dhcppxenfstftp/">http://debianaddict.com/2012/06/19/diskless-debian-linux-booting-via-dhcppxenfstftp/</a></td></tr>
</tbody>
</table>
<hr class="docutils" />
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Status:</th><td class="field-body">$Id: TestBoxImaging.html $</td>
</tr>
<tr class="field"><th class="field-name">Copyright:</th><td class="field-body">Copyright (C) 2010-2023 Oracle Corporation.</td>
</tr>
</tbody>
</table>
</div>
</div>
</body>
</html>
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