VirtualBox

source: vbox/trunk/src/VBox/ValidationKit/docs/TestBoxImaging.html@ 67954

Last change on this file since 67954 was 64653, checked in by vboxsync, 8 years ago

TestBoxImaging.txt: Noted down the solution for PXE showing ARP troubles during TFTPing.

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340<body>
341<div class="document">
342
343
344<div class="section" id="testbox-imaging-backup-restore">
345<h1>Testbox Imaging (Backup / Restore)</h1>
346<div class="section" id="introduction">
347<h2>Introduction</h2>
348<p>This document is explores deloying a very simple drive imaging solution to help
349avoid needing to manually reinstall testboxes when a disk goes bust or the OS
350install seems to be corrupted.</p>
351</div>
352</div>
353<div class="section" id="definitions-glossary">
354<h1>Definitions / Glossary</h1>
355<p>See AutomaticTestingRevamp.txt.</p>
356</div>
357<div class="section" id="objectives">
358<h1>Objectives</h1>
359<blockquote>
360<ul class="simple">
361<li>Off site, no admin interaction (no need for ILOM or similar).</li>
362<li>OS independent.</li>
363<li>Space and bandwidth efficient.</li>
364<li>As automatic as possible.</li>
365<li>Logging.</li>
366</ul>
367</blockquote>
368</div>
369<div class="section" id="overview-of-the-solution">
370<h1>Overview of the Solution</h1>
371<p>Here is a brief summary:</p>
372<blockquote>
373<ul class="simple">
374<li>Always boot testboxes via PXE using PXELINUX.</li>
375<li>Default configuration is local boot (hard disk / SSD)</li>
376<li>Restore/backup action triggered by machine specific PXE config.</li>
377<li>Boots special debian maintenance install off NFS.</li>
378<li>A maintenance service (systemd style) does the work.</li>
379<li>The service reads action from TFTP location and performs it.</li>
380<li>When done the service removes the TFTP machine specific config
381and reboots the system.</li>
382</ul>
383</blockquote>
384<dl class="docutils">
385<dt>Maintenance actions are:</dt>
386<dd><ul class="first last simple">
387<li>backup</li>
388<li>backup-again</li>
389<li>restore</li>
390<li>refresh-info</li>
391<li>rescue</li>
392</ul>
393</dd>
394</dl>
395<p>Possible modifier that indicates a subset of disk on testboxes with other OSes
396installed. Support for partition level backup/restore is not explored here.</p>
397<div class="section" id="how-to-use">
398<h2>How to use</h2>
399<p>To perform one of the above maintenance actions on a testbox, run the
400<tt class="docutils literal"><span class="pre">testbox-pxe-conf.sh</span></tt> script:</p>
401<pre class="literal-block">
402/mnt/testbox-tftp/pxeclient.cfg/testbox-pxe-conf.sh 10.165.98.220 rescue
403</pre>
404<p>Then trigger a reboot. The box will then boot the NFS rooted debian image and
405execute the maintenance action. On success, it will remove the testbox hex-IP
406config file and reboot again.</p>
407</div>
408</div>
409<div class="section" id="storage-server">
410<h1>Storage Server</h1>
411<p>The storage server will have three areas used here. Using NFS for all three
412avoids extra work getting CIFS sharing right too (NFS is already a pain).</p>
413<blockquote>
414<ol class="arabic simple">
415<li>/export/testbox-tftp - TFTP config area. Read-write.</li>
416<li>/export/testbox-backup - Images and logs. Read-write.</li>
417<li>/export/testbox-nfsroot - Custom debian. Read-only, no root squash.</li>
418</ol>
419</blockquote>
420</div>
421<div class="section" id="tftp-export-testbox-tftp">
422<h1>TFTP (/export/testbox-tftp)</h1>
423<p>The testbox-tftp share needs to be writable, root squashing is okay.</p>
424<p>We need files from both PXELINUX and SYSLINUX to make this work now. On a
425debian system, the <tt class="docutils literal">pxelinux</tt> and <tt class="docutils literal">syslinux</tt> packages needs to be
426installed. We actually do this further down when setting up the nfsroot, so
427it's possible to get them from there by postponing this step a little. On
428debian 8.6.0 the PXELINUX files are found in <tt class="docutils literal">/usr/lib/PXELINUX</tt> and the
429SYSLINUX ones in <tt class="docutils literal">/usr/lib/syslinux</tt>.</p>
430<p>The initial PXE image as well as associated modules comes in three variants,
431BIOS, 32-bit EFI and 64-bit EFI. We'll only need the BIOS one for now.
432Perform the following copy operations:</p>
433<pre class="literal-block">
434cp /usr/lib/PXELINUX/pxelinux.0 /mnt/testbox-tftp/
435cp /usr/lib/syslinux/modules/*/ldlinux.* /mnt/testbox-tftp/
436cp -R /usr/lib/syslinux/modules/bios /mnt/testbox-tftp/
437cp -R /usr/lib/syslinux/modules/efi32 /mnt/testbox-tftp/
438cp -R /usr/lib/syslinux/modules/efi64 /mnt/testbox-tftp/
439</pre>
440<p>For simplicitly, all the testboxes boot using good old fashioned BIOS, no EFI.
441However, it doesn't really hurt to be prepared.</p>
442<p>The PXELINUX related files goes in the root of the testbox-tftp share. (As
443mentioned further down, these can be installed on a debian system by running
444<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
445typically found in <tt class="docutils literal">/usr/lib/PXELINUX/</tt> on debian systems (recent ones
446anyway). It is possible we may need one ore more fo the modules <a class="footnote-reference" href="#id6" id="id1">[1]</a> that
447ships with PXELINUX/SYSLINUX, so do copy <tt class="docutils literal">/usr/lib/syslinux/modules</tt> to
448<tt class="docutils literal"><span class="pre">testbox-tftp/modules</span></tt> as well.</p>
449<p>The directory layout related to the configuration files is dictated by the
450PXELINUX configuration file searching algorithm <a class="footnote-reference" href="#id7" id="id2">[2]</a>. Create a subdirectory
451<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
452<tt class="docutils literal">default</tt> with the following content:</p>
453<pre class="literal-block">
454PATH bios
455DEFAULT local-boot
456LABEL local-boot
457LOCALBOOT
458</pre>
459<p>This will make the default behavior to boot the local disk system.</p>
460<p>Copy the <tt class="docutils literal"><span class="pre">testbox-pxe-conf.sh</span></tt> script file found in the same directory as
461this document to <tt class="docutils literal"><span class="pre">/mnt/testbox-tftp/pxelinux.cfg/</span></tt>. Edit the copy to correct
462the IP addresses near the top, as well as any linux, TFTP and PXE details near
463the bottom of the file. This script will generate the PXE configuration file
464when performing maintenance on a testbox.</p>
465</div>
466<div class="section" id="images-and-logs-export-testbox-backup">
467<h1>Images and logs (/export/testbox-backup)</h1>
468<p>The testbox-backup share needs to be writable, root squashing is okay.</p>
469<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
470whether we've actually mounted the share or are just staring at an empty mount
471point directory.</p>
472<p>The <tt class="docutils literal"><span class="pre">testbox-maintenance.sh</span></tt> script maintains a global log in the root
473directory that's called <tt class="docutils literal">maintenance.log</tt>. Errors will be logged there as
474well as a ping and the action.</p>
475<p>We use a directory layout based on dotted decimal IP addresses here, so for a
476server with the IP 10.40.41.42 all its file will be under <tt class="docutils literal">10.40.41.42/</tt>:</p>
477<dl class="docutils">
478<dt><tt class="docutils literal">&lt;hostname&gt;</tt></dt>
479<dd>The name of the testbox (empty file). Help finding a testbox by name.</dd>
480<dt><tt class="docutils literal"><span class="pre">testbox-info.txt</span></tt></dt>
481<dd>Information about the testbox. Starting off with the name, decimal IP,
482PXELINUX style hexadecimal IP, and more.</dd>
483<dt><tt class="docutils literal">maintenance.log</tt></dt>
484<dd>Maintenance log file recording what the maintenance service does.</dd>
485<dt><tt class="docutils literal"><span class="pre">disk-devices.lst</span></tt></dt>
486<dd>Optional list of disk devices to consider backuping up or restoring. This is
487intended for testboxes with additional disks that are used for other purposes
488and should touched.</dd>
489<dt><tt class="docutils literal">sda.raw.gz</tt></dt>
490<dd>The gzipped raw copy of the sda device of the testbox.</dd>
491<dt><tt class="docutils literal"><span class="pre">sd[bcdefgh].raw.gz</span></tt></dt>
492<dd>The gzipped raw copy sdb, sdc, sde, sdf, sdg, sdh, etc if any of them exists
493and are disks/SSDs.</dd>
494<dt>Note! If it turns out we can be certain to get a valid host name, we might just</dt>
495<dd>switch to use the hostname as the directory name instead of the IP.</dd>
496</dl>
497</div>
498<div class="section" id="debian-nfs-root-export-testbox-nfsroot">
499<h1>Debian NFS root (/export/testbox-nfsroot)</h1>
500<p>The testbox-nfsroot share should be read-only and must <strong>not</strong> have root
501squashing enabled. Also, make sure setting the set-uid-bit is allowed by the
502server, or <tt class="docutils literal">su` and ``sudo</tt> won't work</p>
503<p>There are several ways of creating a debian nfsroot, but since we've got a
504tool like VirtualBox around we've just installed it in a VM, prepared it,
505and copied it onto the NFS server share.</p>
506<p>As of writing debian 8.6.0 is current, so a minimal 64-bit install of it was
507done in a VM. After installation the following modifications was done:</p>
508<blockquote>
509<ul>
510<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>
511and optionally <tt class="docutils literal"><span class="pre">apt-get</span> install smbclient <span class="pre">cifs-utils</span></tt>.</p>
512</li>
513<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
514<tt class="docutils literal">&quot;&quot;</tt> instead of <tt class="docutils literal">&quot;quiet&quot;</tt>. This allows us to see messages during boot
515and perhaps spot why something doesn't work on a testbox. Regenerate the
516grub configuration file by running <tt class="docutils literal"><span class="pre">update-grub</span></tt> afterwards.</p>
517</li>
518<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
519requring any password.</p>
520</li>
521<li><p class="first">Create the directory <tt class="docutils literal">/etc/systemd/system/getty&#64;tty1.service.d</tt> and create
522the file <tt class="docutils literal">noclear.conf</tt> in it with the following content:</p>
523<pre class="literal-block">
524[Service]
525TTYVTDisallocate=no
526</pre>
527<p>This stops getty from clearing VT1 and let us see the tail of the boot up
528messages, which includes messages from the testbox-maintenance service.</p>
529</li>
530<li><p class="first">Mount the testbox-nfsroot under <tt class="docutils literal">/mnt/</tt> with write privileges. (The write
531privileges are temporary - don't forget to remove them later on.):</p>
532<pre class="literal-block">
533mount -t nfs myserver.com:/export/testbox-nfsroot
534</pre>
535<p>Note! Adding <tt class="docutils literal"><span class="pre">-o</span> nfsvers=3</tt> may help with some NTFv4 servers.</p>
536</li>
537<li><p class="first">Copy the debian root and dev file system onto nfsroot. If you have ssh
538access to the NFS server, the quickest way to do it is to use <tt class="docutils literal">tar</tt>:</p>
539<pre class="literal-block">
540tar -cz --one-file-system -f /mnt/testbox-maintenance-nfsroot.tar.gz . dev/
541</pre>
542<p>An alternative is <tt class="docutils literal">cp <span class="pre">-ax</span> . /mnt/. &amp;&amp;&nbsp; cp <span class="pre">-ax</span> dev/. /mnt/dev/.</tt> but this
543is quite a bit slower, obviously.</p>
544</li>
545<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
546in as root later on.</p>
547</li>
548<li><p class="first">chroot into the nfsroot: <tt class="docutils literal">chroot /mnt/</tt></p>
549<blockquote>
550<ul>
551<li><p class="first"><tt class="docutils literal">mount <span class="pre">-o</span> proc proc /proc</tt></p>
552</li>
553<li><p class="first"><tt class="docutils literal">mount <span class="pre">-o</span> sysfs sysfs /sys</tt></p>
554</li>
555<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>
556</li>
557<li><p class="first">Recreate <tt class="docutils literal">/etc/fstab</tt> with:</p>
558<pre class="literal-block">
559proc /proc proc defaults 0 0
560/dev/nfs / nfs defaults 1 1
56110.42.1.1:/export/testbox-tftp /mnt/testbox-tftp nfs tcp,nfsvers=3,noauto 2 2
56210.42.1.1:/export/testbox-backup /mnt/testbox-backup nfs tcp,nfsvers=3,noauto 3 3
563</pre>
564<p>We use NFS version 3 as that works better for our NFS server and client,
565remove if not necessary. The <tt class="docutils literal">noauto</tt> option is to work around mount
566trouble during early bootup on some of our boxes.</p>
567</li>
568<li><p class="first">Do <tt class="docutils literal">mount <span class="pre">/mnt/testbox-tftp</span> &amp;&amp; mount <span class="pre">/mnt/testbox-backup</span></tt> to mount the
569two shares. This may be a good time to execute the instructions in the
570sections above relating to these two shares.</p>
571</li>
572<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>
573value from <tt class="docutils literal">most</tt> to <tt class="docutils literal">netboot</tt>.</p>
574</li>
575<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
576multi-layered unification filesystem (aufs) enables us to use a
577read-only NFS root. <a class="footnote-reference" href="#id8" id="id3">[3]</a> <a class="footnote-reference" href="#id9" id="id4">[4]</a> <a class="footnote-reference" href="#id10" id="id5">[5]</a></p>
578</li>
579<li><p class="first">Create <tt class="docutils literal"><span class="pre">/etc/initramfs-tools/scripts/init-bottom/00_aufs_init</span></tt> as
580an executable file with the following content:</p>
581<pre class="literal-block">
582#!/bin/sh
583# Don't run during update-initramfs:
584case &quot;$1&quot; in
585 prereqs)
586 exit 0;
587 ;;
588esac
589
590modprobe aufs
591mkdir -p /ro /rw /aufs
592mount -t tmpfs tmpfs /rw -o noatime,mode=0755
593mount --move $rootmnt /ro
594mount -t aufs aufs /aufs -o noatime,dirs=/rw:/ro=ro
595mkdir -p /aufs/rw /aufs/ro
596mount --move /ro /aufs/ro
597mount --move /rw /aufs/rw
598mount --move /aufs /root
599exit 0
600</pre>
601</li>
602<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>
603<dl class="docutils">
604<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>
605<dd><p class="first last">this operation succeed.</p>
606</dd>
607</dl>
608</li>
609<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>
610</li>
611<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
612document to <tt class="docutils literal">/root/scripts/</tt> (need to create the dir) and make it
613executable.</p>
614</li>
615<li><p class="first">Create the systemd service file for the maintenance service as
616<tt class="docutils literal"><span class="pre">/etc/systemd/system/testbox-maintenance.service</span></tt> with the content:</p>
617<pre class="literal-block">
618[Unit]
619Description=Testbox Maintenance
620After=network.target
621Before=getty&#64;tty1.service
622
623[Service]
624Type=oneshot
625RemainAfterExit=True
626ExecStart=/root/scripts/testbox-maintenance.sh
627ExecStartPre=/bin/echo -e \033%G
628ExecReload=/bin/kill -HUP $MAINPID
629WorkingDirectory=/tmp
630Environment=TERM=xterm
631StandardOutput=journal+console
632
633[Install]
634WantedBy=multi-user.target
635</pre>
636</li>
637<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>
638</li>
639<li><p class="first">xxxx ... more ???</p>
640</li>
641<li><p class="first">Before leaving the chroot, do <tt class="docutils literal">mount /proc /sys <span class="pre">/mnt/testbox-*</span></tt>.</p>
642</li>
643</ul>
644</blockquote>
645</li>
646<li><p class="first">Testing the setup from a VM is kind of useful (if the nfs server can be
647convinced to accept root nfs mounts from non-privileged clinet ports):</p>
648<blockquote>
649<ul>
650<li><p class="first">Create a VM using the 64-bit debian profile. Let's call it &quot;pxe-vm&quot;.</p>
651</li>
652<li><p class="first">Mount the TFTP share somewhere, like M: or /mnt/testbox-tftp.</p>
653</li>
654<li><p class="first">Reconfigure the NAT DHCP and TFTP bits:</p>
655<pre class="literal-block">
656VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/AboveDriver NAT
657VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/Action mergeconfig
658VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/Config/TFTPPrefix M:/
659VBoxManage setextradata pxe-vm VBoxInternal/PDM/DriverTransformations/pxe/Config/BootFile pxelinux.0
660</pre>
661</li>
662<li><p class="first">Create the file <tt class="docutils literal"><span class="pre">testbox-tftp/pxelinux.cfg/0A00020F</span></tt> containing:</p>
663<pre class="literal-block">
664PATH bios
665DEFAULT maintenance
666LABEL maintenance
667 MENU LABEL Maintenance (NFS)
668 KERNEL maintenance-boot/vmlinuz-3.16.0-4-amd64
669 APPEND initrd=maintenance-boot/initrd.img-3.16.0-4-amd64 ro ip=dhcp aufs=tmpfs \
670 boot=nfs root=/dev/nfs nfsroot=10.42.1.1:/export/testbox-nfsroot
671LABEL local-boot
672LOCALBOOT
673</pre>
674</li>
675</ul>
676</blockquote>
677</li>
678</ul>
679</blockquote>
680</div>
681<div class="section" id="troubleshooting">
682<h1>Troubleshooting</h1>
683<dl class="docutils">
684<dt><tt class="docutils literal"><span class="pre">PXE-E11</span></tt> or something like <tt class="docutils literal">No ARP reply</tt></dt>
685<dd>You probably got the TFTP and DHCP on different machines. Try move the TFTP
686to the same machine as the DHCP, then the PXE stack won't have to do any
687additional ARP resolving. Google results suggest that a congested network
688could use the ARP reply to get lost. Our suspicion is that it might also be
689related to the PXE stack shipping with the NIC.</dd>
690</dl>
691<hr class="docutils" />
692<table class="docutils footnote" frame="void" id="id6" rules="none">
693<colgroup><col class="label" /><col /></colgroup>
694<tbody valign="top">
695<tr><td class="label"><a class="fn-backref" href="#id1">[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>
696</tbody>
697</table>
698<table class="docutils footnote" frame="void" id="id7" rules="none">
699<colgroup><col class="label" /><col /></colgroup>
700<tbody valign="top">
701<tr><td class="label"><a class="fn-backref" href="#id2">[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>
702</tbody>
703</table>
704<table class="docutils footnote" frame="void" id="id8" rules="none">
705<colgroup><col class="label" /><col /></colgroup>
706<tbody valign="top">
707<tr><td class="label"><a class="fn-backref" href="#id3">[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>
708</tbody>
709</table>
710<table class="docutils footnote" frame="void" id="id9" rules="none">
711<colgroup><col class="label" /><col /></colgroup>
712<tbody valign="top">
713<tr><td class="label"><a class="fn-backref" href="#id4">[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>
714</tbody>
715</table>
716<table class="docutils footnote" frame="void" id="id10" rules="none">
717<colgroup><col class="label" /><col /></colgroup>
718<tbody valign="top">
719<tr><td class="label"><a class="fn-backref" href="#id5">[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>
720</tbody>
721</table>
722<hr class="docutils" />
723<table class="docutils field-list" frame="void" rules="none">
724<col class="field-name" />
725<col class="field-body" />
726<tbody valign="top">
727<tr class="field"><th class="field-name">Status:</th><td class="field-body">$Id: TestBoxImaging.html 64653 2016-11-11 21:57:24Z vboxsync $</td>
728</tr>
729<tr class="field"><th class="field-name">Copyright:</th><td class="field-body">Copyright (C) 2010-2016 Oracle Corporation.</td>
730</tr>
731</tbody>
732</table>
733</div>
734</div>
735</body>
736</html>
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