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Description:

updatedotdee 6.0

The update-dotdee program makes it easy to manage configuration files with
modular contents in the style of Debian and dotdee. The program takes the
pathname of a configuration file and updates that file based on the contents of
the files in the directory with the same name as the file but ending in .d.
It’s currently tested on cPython 2.7, 3.5+ and PyPy (2.7).

Installation
Usage
Example
How it works
Use cases
Read only alternative
Contact
License

Installation
The update-dotdee package is available on PyPI which means installation
should be as simple as:
$ pip install update-dotdee
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 ;-).

Usage
There are two ways to use the update-dotdee package: As the command line
program update-dotdee and as a Python API. For details about the Python API
please refer to the API documentation available on Read the Docs. The
command line interface is described below.
Usage: update-dotdee FILENAME
Generate a (configuration) file based on the contents of the files in the
directory with the same name as FILENAME but ending in ‘.d’.
If FILENAME exists but the corresponding directory does not exist yet, the
directory is created and FILENAME is moved into the directory so that its
existing contents are preserved.
Supported options:

Option
Description

-f, --force
Update FILENAME even if it contains local modifications,
instead of aborting with an error message.

-u, --use-sudo
Enable the use of “sudo” to update configuration files that are not
readable and/or writable for the current user (or the user logged
in to a remote system over SSH).

-r, --remote-host=SSH_ALIAS
Operate on a remote system instead of the local system. The
SSH_ALIAS argument gives the SSH alias of the remote host.

-v, --verbose
Increase logging verbosity (can be repeated).

-q, --quiet
Decrease logging verbosity (can be repeated).

-h, --help
Show this message and exit.

Example
The /etc/hosts file is a simple example of a configuration file that can be
managed using update-dotdee. Individual files in the /etc/hosts.d directory
contain snippets that are added to the configuration file on each run. For
example:
peter@macbook> sudo update-dotdee /etc/hosts
2013-07-06 19:32:03 macbook INFO Reading file: /etc/hosts.d/1-local
2013-07-06 19:32:03 macbook INFO Reading file: /etc/hosts.d/2-work
2013-07-06 19:32:03 macbook INFO Reading file: /etc/hosts.d/3-ipv6
2013-07-06 20:59:24 macbook INFO Checking for local changes to /etc/hosts
2013-07-06 19:32:03 macbook INFO Writing file: /etc/hosts

How it works
Some notes about how update-dotdee works:

If the given file exists but the corresponding directory does not exist yet,
the directory is created and the file is moved into the directory (and
renamed to local) so that its existing contents are preserved.
If the generated file has been modified since the last run, update-dotdee
will refuse to overwrite its contents (unless you use the -f or
--force option).
The files in the .d directory are concatenated in the natural sorting
order of the filenames (as implemented by the naturalsort package).
Executable files in the .d directory are executed and their standard
output is incorporated into the generated contents (since version 4.0).

Use cases
Here are some example use cases for update-dotdee:

SSH client configuration
The update-dotdee program was created in 2013 to provide modular SSH client
configurations. It was used to generate the ~/.ssh/config file from the
contents of the files in the ~/.ssh/config.d directory. This functionality
was needed because I developed an SSH client configuration generator based on
a database of server metadata and I was looking for a way to update the user’s
~/.ssh/config without trashing the existing (carefully handcrafted)
contents.

System wide configuration files
Linux system configuration files like /etc/crypttab, /etc/fstab and
/etc/hosts lack modularity and manipulating them using command line tools
like awk and sed can be fragile and/or become unwieldy :-). However if you
can get your configuration sources (for example Ansible playbooks, Debian
packages and manual configuration) to agree on the use of update-dotdee then
you have an elegant, robust and predictable alternative.

Read only alternative
Sometimes the use of update-dotdee or a similar mechanism is the only way to
get multiple configuration sources to cooperate, but it is a bit of a
heavyweight solution. For the Python packages that I’ve published I wanted a
more lightweight alternative that simply searches for and loads *.ini
configuration files. This is why ConfigLoader was added in release 5.0.

Contact
The latest version of update-dotdee is available on PyPI and GitHub. The
documentation is hosted on Read the Docs and includes a changelog. For bug
reports please create an issue on GitHub. If you have questions, suggestions,
etc. feel free to send me an e-mail at peter@peterodding.com.

License
This software is licensed under the MIT license.
© 2020 Peter Odding.