debuntu-tools 0.4

Debian and Ubuntu system administration tools

The debuntu-tools package is my playground for experiments in automating system administration tasks on Debian and Ubuntu Linux systems. Right now there’s just four programs and no test suite, but I intend to keep working on this package in order make it a lot more useful. For usage instructions please refer to following sections and the documentation.

Contents

• Status

• Installation

  • Requirements

• Usage

  • debuntu-kernel-manager

  • debuntu-nodejs-installer

  • reboot-remote-system

  • unlock-remote-system

• Configuration files

• Contact

• License

Status

Right now debuntu-tools is just an experiment and as such I’m not making any claims about or commitments towards usability, reliability or backwards compatibility. I guess we’ll see how long it’s going to take me to consider this more than an experiment :-). The programs in this package have been manually tested on and are being used to manage headless Linux servers running Ubuntu 14.04 and 16.04.

Installation

The debuntu-tools package is available on PyPI which means installation should be as simple as:

$ pip install debuntu-tools

There’s actually a multitude of ways to install Python packages (e.g. the per user site-packages directory, virtual environments or just installing system wide) and I have no intention of getting into that discussion here, so if this intimidates you then read up on your options before returning to these instructions ;-).

Requirements

• Several Python packages are required by debuntu-tools but installation of the Python package should automatically pull in those dependencies for you.

• The debuntu-kernel-manager program expects to be running on a Debian or Ubuntu derived Linux distribution, more specifically you need a functional dpkg installation. This enables version sorting according to the semantics used by dpkg, which is quite significant if your goal is to remove older kernels but preserve newer ones :-). To actually install and remove kernel packages you need apt-get and sudo privileges on the system whose kernels are being managed.

• The unlock-remote-system program expects a remote Linux system that has been configured in such a way that the pre-boot environment (the initial ramdisk) enables a static IP address and starts an SSH server like dropbear.

Usage

There are two ways to use the debuntu-tools package:

1. The command line interfaces which are described below.

2. The Python API which is documented on Read the Docs.

The following programs are documented here:

• debuntu-kernel-manager

• debuntu-nodejs-installer

• reboot-remote-system

• unlock-remote-system

debuntu-kernel-manager

Usage: debuntu-kernel-manager [OPTIONS] – [APT_OPTIONS]

Detect and remove old Linux kernel header and image packages that can be safely removed to conserve disk space and speed up apt-get runs that install or remove kernels.

By default old packages are detected and reported on the command line but no changes are made. To actually remove old packages you need to use the -c, --clean or --remove option. Using the following command you can perform a dry run that shows you what will happen without actually doing it:

$ debuntu-kernel-manager --remove -- --dry-run

The debuntu-kernel-manager program is currently in alpha status, which means a first attempt at a usable program has been published but there are no guarantees about what it actually does. You have been warned :-).

Supported options:

Option	Description
-c, --clean, --remove	Remove Linux kernel header and/or image packages that are deemed to be safe to remove. The use of this option requires sudo access on the system in order to run the ‘apt-get remove’ command.
-f, --force	When more than one Linux kernel meta package is installed the -c, --clean and --remove options will refuse to run apt-get and exit with an error instead. Use the -f or --force option to override this sanity check.
-p, --preserve-count=NUMBER	Preserve the NUMBER newest versions of the kernel packages (defaults to 2).
-r, --remote-host=ALIAS	Detect and remove old Linux kernel header and image packages on a remote host over SSH. The ALIAS argument gives the SSH alias that should be used to connect to the remote host.
-v, --verbose	Increase verbosity (can be repeated).
-q, --quiet	Decrease verbosity (can be repeated).
-h, --help	Show this message and exit.

debuntu-nodejs-installer

Usage: debuntu-nodejs-installer [OPTIONS]

Install an up to date Node.js binary distribution on a Debian or Ubuntu system by configuring and using the NodeSource binary package repositories.

Due to the time it takes for new software releases to find their way into the Debian and Ubuntu ecosystems versus the speed with which the Node.js community is currently moving, the system packages that provide Node.js are hopelessly out of date. Fortunately the folks at NodeSource maintain Debian and Ubuntu package repositories that provide up to date Node.js binary distributions.

NodeSource makes installation scripts available and the suggested way to run these is to download and pipe them straight to a shell. That kind of rubs me the wrong way :-) but I’ve nevertheless had to set up NodeSource installations a dozen times now. One thing led to another and now there is this program.

Supported options:

Option	Description
-i, --install	Configure the system to use one of the NodeSource binary package repositories and install the ‘nodejs’ package from the repository.
-V, --version=NODEJS_VERSION	Set the version of Node.js to be installed. You can find a list of available versions on the following web page: https://github.com/nodesource/distributions/ Default: node_4.x
-s, --sources-file=FILENAME	Set the pathname of the ‘package resource list’ that will be added to the system during configuration of the NodeSource binary package repository. Default: /etc/apt/sources.list.d/nodesource.list
-r, --remote-host=ALIAS	Perform the requested action(s) on a remote host over SSH. The ALIAS argument gives the SSH alias that should be used to connect to the remote host.
-v, --verbose	Increase verbosity (can be repeated).
-q, --quiet	Decrease verbosity (can be repeated).
-h, --help	Show this message and exit.

reboot-remote-system

Usage: reboot-remote-system [OPTIONS] [SSH_ALIAS]

Reboot a remote system and wait for the system to come back online. If the SSH alias matches a section in the ‘unlock-remote-system’ configuration, the root disk encryption of the remote system will be unlocked after it is rebooted.

Supported options:

Option	Description
-s, --shell	Start an interactive shell on the remote system after it has finished booting.
-v, --verbose	Increase logging verbosity (can be repeated).
-q, --quiet	Decrease logging verbosity (can be repeated).
-h, --help	Show this message and exit.

unlock-remote-system

Usage: unlock-remote-system [OPTIONS] PRE_BOOT [POST_BOOT]

Boot a remote Linux system that’s waiting for the root disk encryption password to be entered into an interactive prompt by connecting to the remote system over the network using SSH and entering the password non-interactively. The remote Linux system needs to be configured in such a way that the pre-boot environment enables a static IP address and starts an SSH server like Dropbear.

The PRE_BOOT argument defines how to connect to the pre-boot environment:

• Its value is assumed to be a host name, IP address or SSH alias.

• It can optionally start with a username followed by an ‘@’ sign.

• It can optionally end with a ‘:’ followed by a port number.

The default username is ‘root’ and the default port number 22. The optional POST_BOOT argument defines how to connect to the post-boot environment, this is useful when the pre and post-boot environments run SSH servers on different port numbers.

If the PRE_BOOT argument matches the name of a user defined configuration section the options in that section define how unlock-remote-system operates.

Supported options:

Option	Description
-i, --identity-file=KEY_FILE	Use the private key stored in KEY_FILE for SSH connections to the pre-boot environment. The post-boot environment is expected to use your default private key or have a suitable configuration in ~/.ssh/config.
-k, --known-hosts=HOSTS_FILE	Use HOSTS_FILE as the “known hosts file” for SSH connections to the pre-boot environment. When this option is not given host key verification will be disabled to avoid conflicts between the host keys of the different SSH servers running in the pre-boot and post-boot environments.
-p, --password=NAME	Get the password for the root disk encryption of the remote system from the local password store in ~/.password-store using the ‘pass’ program. The NAME argument gives the full name of the password.
-r, --remote-host=SSH_ALIAS	Connect to the remote system through an SSH proxy.
-s, --shell	Start an interactive shell on the remote system after it has finished booting.
-w, --watch	Start monitoring the remote system and automatically unlock the root disk encryption when the remote system is rebooted. The monitoring continues indefinitely.
-a, --all	Enable monitoring of all configured systems when combined with --watch.
-v, --verbose	Increase logging verbosity (can be repeated).
-q, --quiet	Decrease logging verbosity (can be repeated).
-h, --help	Show this message and exit.

Configuration files

unlock-remote-system

Configuration files are text files in the subset of ini syntax supported by Python’s configparser module. They can be located in the following places:

Directory	Main configuration file	Modular configuration files
/etc	/etc/unlock-remote-system.ini	/etc/unlock-remote-system.d/*.ini
~	~/.unlock-remote-system.ini	~/.unlock-remote-system.d/*.ini
~/.config	~/.config/unlock-remote-system.ini	~/.config/unlock-remote-system.d/*.ini

The available configuration files are loaded in the order given above, so that user specific configuration files override system wide configuration files.

Each section of the configuration applies to a single host. The following options are supported in these sections:

Configuration option	Default value
boot-timeout	5 minutes
connect-timeout	60 seconds
cryptroot-config	/conf/conf.d/cryptroot
cryptroot-program	/scripts/local-top/cryptroot
key-script	/tmp/keyscript.sh
known-hosts-file	(no value)
named-pipe	/lib/cryptsetup/passfifo
password	(no value)
password-name	(no value)
password-store	(no value)
post-boot	(no value)
pre-boot	(no value)
retry-interval	1 second
scan-timeout	5 seconds
ssh-proxy	(no value)

The links in the table above lead to the Python API documentation which explains the purpose of each of these options.

Contact

The latest version of debuntu-tools is available on PyPI and GitHub. The documentation is hosted on Read the Docs. For bug reports please create an issue on GitHub. If you have questions, suggestions, etc. feel free to send me an e-mail at [e-mail].

License

This software is licensed under the MIT license.

© 2018 Peter Odding.