mjhennig / hostname-setup

Hostname Setup At Boot Time

Hostname Setup At Boot Time

The hostname-setup package provides an easy way to setup the hostname of a system at boot time. This can be quite usefull when creating a prototype image that is to be used as the base for multiple systems, especially when one wants to avoid the creation of a custom installer.

Contents

Below please find a list of the main contents of the hostname-setup package:

• /etc/default/hostname-setup
  The main configuration. A detailled explanation can be found in the Configuration section below.

• /etc/init.d/hostname-prompt
  A wrapper around hostname-setup to be registered with initrd. When invoked, it will check whether the current persistent hostname already fulfills the HOSTNAME_SETUP_ALLOW and HOSTNAME_SETUP_DENY patterns and, if not, prompt the for a new hostname to setup.

• /etc/init.d/hostname-persist
  A wrapper around hostname-setup to be registered with initrd. When invoked, it updates /etc/hostname, /etc/hosts and /etc/mailname, according to the current hostname.

• /sbin/hostname-setup
  The main script. When invoked directly, it will perform all operations at once, just like hostname-prompt and hostname-persist when one's invoking them in sequence.

Please note that the wrapper scripts are independent from each other. One could, for example, use hostname-prompt only - in order to always request a hostname to be entered when the system is started, not only during the first boot. Anyway, the primary reason for this separation is the fact that the system determines it's own hostname when /etc is still mounted read-only. Thus; persisting the configuration, if required, needs to be done later.

Requirements

Currently, the hostname-setup script works with Debian and derivates like Ubuntu, requiring only a base system. The following releases have been tested and verified so far:

• Debian GNU/Linux 7.x "wheezy"
• Debian GNU/Linux 6.x "squeeze"
• Debian GNU/Linux 5.x "lenny"
• Ubuntu 12.10 "Quantal Quetzal"
• Ubuntu 12.04 "Precise Pangolin"

The package should work with any initrd-based system that's using the /etc/hostname and /etc/hosts files, without or with minor adjustments.

Other systems haven't been adopted yet. Contributions are welcome!

Installation

Installation differs between various OS and init mechanisms. This package does NOT include an official installation process, and manual modifications of boot scripts should be done by experienced operators only!

Anyway, below please find an example for Debian Squeeze, which should work for most derivates using initrd:

# Fetching latest source from master
user@host:~$ git clone git://github.com/mjennig/hostname-setup.git

# Installing the init scripts
user@host:~$ sudo cp -i hostname-setup/etc/init.d/hostname-* /etc/init.d/
# Installing the configuration files
user@host:~$ sudo cp -i hostname-setup/etc/default/hostname-* /etc/default/
# Installing the main script
user@host:~$ sudo cp -i hostname-setup/sbin/hostname-* /sbin/

# Custom configuration
user@host:~$ sudo vim /etc/default/hostname-setup

# Enable prompting at boot time
user@host:~$ sudo update-rc.d hostname-prompt start 01 S
# Enable persisting at boot time
user@host:~$ sudo update-rc.d hostname-persist start 01 S

Note: On any initrd based system, one should verify the compatibility of each script's LSB header! See http://wiki.debian.org/LSBInitScripts for more information about this topic.

Configuration

All configuration is done by modifying /etc/default/hostname-setup. The contents of this file are pretty self-explanatory:

# The default hostname whitelist pattern
: ${HOSTNAME_SETUP_ALLOW:="[[:alnum:]\\-]\\+"}

# The default hostname blacklist pattern
: ${HOSTNAME_SETUP_DENY:="localhost"}

# The default prompt to ask for a new hostname
: ${HOSTNAME_SETUP_PROMPT:="Please enter a new name for this host: "}

# The path to the hostname(1) executable
: ${HOSTNAME_SETUP_HOSTNAME:="`which hostname 2>/dev/null`"}

Note that the (POSIX) regular expressions are interpreted with implicit leading ^ and trailing $, so they must apply to the entire hostname.

Resources

Below please find a list of resources associated with the hostname-setup package:

• Source-Code: https://github.com/mjennig/hostname-setup
• Issue-Tracker: https://github.com/mjennig/hostname-setup/issues

Copyright & License

Copyright (c) 2013 Mathias J. Hennig

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.