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--- linux:debian:automatic-installation [2013/06/20 07:10] – [When things go wrong - unusual/additional questions asked] reword and clarify some things, especially regarding 7.1 problems stybla
+++ linux:debian:automatic-installation [2013/06/25 05:06] (current) – finish up - foreword, conclusion and some other stuff stybla
@@ Line 1: / Line 1: @@
 ====== Debian - Automatic Installation ======
-<note warning>
+===== Foreword of sorts =====
-**WORK IN PROGRESS**
-  * NOTE to myself - preseed file can be supplied by DHCP
-  * NOTE to myself - preseed generated by CGI script
-</note>
 As a pretty much any mainstream GNU/Linux distribution, even Debian allows you to automate
-system installation. You can either use Preseed or build a custom ramdisk and use debootstrap
+system installation. You can either use Preseed or a custom built ramdisk and use debootstrap
 directly.
-No doubt each approach has its own pros and cons. Personally, I think Preseed is sufficient for
+When I told my friend I'm looking into preseeding Debian he was like: //What's wrong with debootstrap?//
-most cases and basic OS installation is what you (should) want. After OS is sucessfully installed,
+The answer is there is nothing wrong with deboostrap and custom built ramdisk except it's a bit of work.
-Ansible/Chef/Puppet will take over and finish the job. I really seek nothing else from OS
+So why not to use Preseeding if it can do the job?
-installation. Preseed is capable of handling not only partitions, but software RAID and LVM as well.
-You can also run commands and do stuff, although admitingly in limited scope.
+No doubt each approach has its pros and cons. I'm positive custom build ramdisk and deboostrap
+will be faster than installer. Also, you can add tools you need, eg. tools for HW RAID, but you
+can do a bit of scripting(and magic) as well, eg. assemble HW RAID prior to installation. Ramdisk can be used for
+rescue and debugging. As a con I see maintenance - you have to create it, script(automate) it and keep it up-to-date.
+Preseeding has pretty much the same capabilities. It allows you to install base Debian which is, in my opinion,
+all you need and fine-tune the rest with Ansible/Chef/Puppet/or-alike after installation; install additional
+packages; support for LVM and Linux SW RAID; run additional commands; what have you. I'd almost forget you
+can use Preseed for installation from USB/DVD/CD as well! And it's all maintained for you.
+Now, here are some cons which, despite solveable, are a bit annoying.
+==== Cons of Debian Preseeding ====
+=== Things don't always work out-of-the-box ===
+For example I didn't have much of success with network console. It just kept segfaulting on me at "random" points.
+You might want to use different kernel, although replacing kernel should be the least warry and quite easy.
+Something can be or get broken or there is going to be some sort of regression.
+=== More than one Preseed configuration might be necessary ===
+This might be due to the differences in hardware configuration. The thing is, you must specify target drive in case
+there is more than one drive present. And I'm sure this isn't uncommon case. However, this can be solved by simple
+CGI/script preseed generator which will return correct Preseed configuration file, eg. based on hostname.
+=== Missing tools ===
+I believe you could easilly add whatever you want and pretty much modify netboot ramdisk in way you like.
+=== MD5 sum of Preseed config must be kept up to date ===
+Yes, this is particularly annoying one. You can solve it in two ways. Don't use MD5 sum, however then you can't be sure
+about integrity of preseed file you've just downloaded. Or just integrate it into your script you have for updating TFTP
+boot configuration. I don't really think this is a hard one to do.
+=== Can't be used for rescue and/or debugging ===
+I'm not entirely sure this is true. I also think with a bit of work and modification it very well could be.
+===== Conclusion of sorts =====
-On the other hand, customized ramdisk can provide you with universal solution - one rules them all.
+I find Debian Preseeding to be enough. It does basic Debian installation which is all I need, because after installation
-You can add vendor specific tools, assemble HW RAIDs, debug/fix broken OS, run pre/post install tasks
+is finished, I hand it over to Ansible/Chef/Puppet/whatever to fine tune system for specific task. I don't mind the time it takes
-via your favourite management tool etc. and create one ramdisk for OS install and rescue.
+to install Debian via Installer, although I will look into custom built ramdisk sooner or later. More out of
+curiosity rather than actual need, I guess. As I mentioned, not every time things work out-of-the-box. However,
+the same can be said about everything and it's something you have to accept and be aware of - always.
-Now, you might argue every server(hardware configuration) is different and requires specific approach.
-I'd counter-argue it's more about profiling and you end up with only couple profiles. I agree
-stuff like HW RAID assembly and vendor specific tools to do that might be a problem. However, you can
-modify Debian's netboot ramdisk and add these. Preseed allows you to run early command(s). Is it early
-enough to assembly HW RAID? Would installer notice/update its device list? I don't know, I haven't tried.
-I still think rolling with Preseed for basic OS installation is better and easier to maintain way than
-having to maintain your customized ramdisk. Althouhg, once you automate its [ramdisk] creation, then
-it won't matter that much.
 ===== Customized ramdisk and debootstrap =====
@@ Line 43: / Line 71: @@
 a way it boots into shell instead of installer, add stuff you need want, remove stuff you don't need,
 pack it, run with it.
 ===== Preseeding =====
@@ Line 48: / Line 78: @@
   * TFTP, DHCP, web server
+  * [[linux:debian:apt-mirror|local Debian mirror]] can be handy, but isn't mandatory
   * time
   * patience
 ==== Example of preseed file ====
+I've removed pretty much all comments. What's below is my preseed file.
+Please, see example preseed files/documentation for explanation, hints
+and, actually, more.
 <code>
-# Preseeding only locale sets language, country and locale.
+### l18n, i18n, keyboard
 d-i debian-installer/locale string en_US
-# The values can also be preseeded individually for greater flexibility.
 d-i debian-installer/language string en
 d-i debian-installer/country string CZ
-# Keyboard selection.
 # keymap is an alias for keyboard-configuration/xkb-keymap
 d-i keymap select us
 ### Network configuration
-# netcfg will choose an interface that has link if possible. This makes it
+# netcfg will choose an interface that has link if possible.
-# skip displaying a list if there is more than one interface.
 d-i netcfg/choose_interface select auto
-# If you have a slow dhcp server and the installer times out waiting for
+# In case of a slow dhcp server
-# it, this might be useful.
 d-i netcfg/dhcp_timeout string 60
-# Any hostname and domain names assigned from dhcp take precedence over
+# despite defined here, it must be preseeded via cmd line as well
-# values set here. However, setting the values still prevents the questions
-# from being shown, even if values come from dhcp.
 d-i netcfg/get_hostname string unassigned-hostname
 d-i netcfg/get_domain string unassigned-domain
-# Disable that annoying WEP key dialog.
 d-i netcfg/wireless_wep string
-# If non-free firmware is needed for the network or other hardware, you can
+# load non-free firmware without asking
-# configure the installer to always try to load it, without prompting. Or
-# change to false to disable asking.
 d-i hw-detect/load_firmware boolean true
@@ Line 86: / Line 114: @@
 d-i mirror/protocol string http
 d-i mirror/country string cz
-d-i mirror/http/hostname string debian.mirror.dkm.cz
+d-i mirror/http/hostname string test-deb-01.vm.zeratul.czf
 d-i mirror/http/directory string /debian
 d-i mirror/http/proxy string
@@ Line 98: / Line 126: @@
 ### Clock and time zone setup
-# Controls whether or not the hardware clock is set to UTC.
 d-i clock-setup/utc boolean true
-# You may set this to any valid setting for $TZ; see the contents of
-# /usr/share/zoneinfo/ for valid values.
 d-i time/zone string UTC
-# Controls whether to use NTP to set the clock during the install
 d-i clock-setup/ntp boolean true
-# NTP server to use. The default is almost always fine here.
 d-i clock-setup/ntp-server ntp.vm.zeratul.czf
 ### Partitioning
-## Partitioning example
+# this must be set in case you have more than one HDD present
-# If the system has free space you can choose to only partition that space.
+d-i partman-auto/disk string /dev/vda
-# This is only honoured if partman-auto/method (below) is not set.
+# possible values: regular, lvm, crypto
-#d-i partman-auto/init_automatically_partition select biggest_free
-# Alternatively, you may specify a disk to partition. If the system has only
-# one disk the installer will default to using that, but otherwise the device
-# name must be given in traditional, non-devfs format (so e.g. /dev/hda or
-# /dev/sda, and not e.g. /dev/discs/disc0/disc).
-# For example, to use the first SCSI/SATA hard disk:
-#d-i partman-auto/disk string /dev/sda
-# In addition, you'll need to specify the method to use.
-# The presently available methods are:
-# - regular: use the usual partition types for your architecture
-# - lvm:     use LVM to partition the disk
-# - crypto:  use LVM within an encrypted partition
 d-i partman-auto/method string lvm
-# If one of the disks that are going to be automatically partitioned
-# contains an old LVM configuration, the user will normally receive a
-# warning. This can be preseeded away...
 d-i partman-lvm/device_remove_lvm boolean true
-# The same applies to pre-existing software RAID array:
 d-i partman-md/device_remove_md boolean true
-# And the same goes for the confirmation to write the lvm partitions.
 d-i partman-lvm/confirm boolean true
 d-i partman-lvm/confirm_nooverwrite boolean true
-# You can choose one of the three predefined partitioning recipes:
-# - atomic: all files in one partition
+# possible values - atomic, home, multi
-# - home:   separate /home partition
-# - multi:  separate /home, /usr, /var, and /tmp partitions
 d-i partman-auto/choose_recipe select atomic
-# This makes partman automatically partition without confirmation, provided
-# that you told it what to do using one of the methods above.
 d-i partman-partitioning/confirm_write_new_label boolean true
 d-i partman/choose_partition select finish
 d-i partman/confirm boolean true
 d-i partman/confirm_nooverwrite boolean true
-# This makes partman automatically partition without confirmation.
 d-i partman-md/confirm boolean true
 d-i partman-partitioning/confirm_write_new_label boolean true
@@ Line 166: / Line 168: @@
 d-i grub-installer/only_debian boolean true
 d-i grub-installer/with_other_os boolean true
-d-i grub-installer/bootdev string (hd0,0)
 ### Finishing up the installation
 # Avoid that last message about the install being complete.
 d-i finish-install/reboot_in_progress note
-# This will prevent the installer from ejecting the CD during the reboot,
+# don't eject CD as there isn't any
-# which is useful in some situations.
 d-i cdrom-detect/eject boolean false
 # Setup SSH keys for root; the last command to be run before reboot
-d-i preseed/late_command string wget http://test-deb-01.vm.zeratul.czf/set-ssh-keys.sh; sh set-ssh-keys.sh;
+d-i preseed/late_command string wget http://test-deb-01.vm.zeratul.czf/preseed/set-ssh-keys.sh; sh set-ssh-keys.sh;
 </code>
@@ Line 187: / Line 187: @@
   APPEND initrd=img/debian64-7.1.0-wheezy-initrd.img \
     auto \
-    url=http://test-deb-01.vm.zeratul.czf/preseed.cfg \
+    url=http://test-deb-01.vm.zeratul.czf/preseed/preseed.cfg \
     preseed-md5=299d7a67793464e7e1e013a79660b64e \
     fb=false \
@@ Line 214: / Line 214: @@
   * **netcfg/dhcp_timeout** - just for sure
   * **netcfg/get_hostname**, **netcfg/get_domain** - despite set from DHCP, installer kept asking for confirmation unless defaults were passed as kernel param
+Turning off Frame Buffer(''fb'') in installer is usefull when eg. ''curses'' is used instead of ''SDL'' to display VGA output.
+However, turning Frame Buffer off means graphics in installer will go wonky from time to time even when running in SDL window.
+==== How to configure network-console, how can it be used? ====
+<code>
+### Network console
+# Use the following settings if you wish to make use of the network-console
+# component for remote installation over SSH. This only makes sense if you
+# intend to perform the remainder of the installation manually.
+d-i anna/choose_modules string network-console
+d-i network-console/authorized_keys_url string http://test-deb-01.vm.zeratul.czf/preseed/authorized_keys
+#d-i network-console/password password r00tme
+#d-i network-console/password-again password r00tme
+</code>
+This happens before APT repository is configured. You're presented with instructions and I believe as long
+as you don't click //Continue// installer will wait indefinitely. Then you can login via SSH as user
+''installer'' and either continue installation(I believe Preseed will be used), you can continue installation
+manually, or switch into shell.
+Note, however, network-console has segfaulted(Wheezy 7.1) on my on several occasions. The first was when
+I attempted to get into shell and second when I've clicked //Continue// in installer and tried to log-in
+via SSH when installation proceeded.
+==== When is ''early_command'' being executed? ====
+Before APT repository is configured.
+==== When is ''late_command'' being executed? ====
+Just before machine is about to be rebooted. However ''/target'' is still mounted.