Mud is a small tool to automate deployment and undeployment of applications. It stands for Multi Version Deployer as it has been built for this purpose even if it can work with single-version projects as well.

Configuration

The simpler case is an application having one deploy script and one undeploy script. The configuration files are in /usr/local/etc/mud by default. For instance, if the application you want to deploy is called 'my-app', mud will read the file /usr/local/etc/mud/my-app.conf.

IMPORTANT NOTE: This directory should NOT be world-writable as an attacker could use it to add other files like common typos (myapp.conf, myAPp.conf, etc.) which would be read and "executed" by the user calling mud should he/she misspelled the project name. Of course, it would be even worse if the files themselves are world-writable.

A configuration file looks like this:

deploy=/usr/local/etc/mud/my-app.deploy
undeploy=/usr/local/etc/mud/my-app.undeploy
basepath=/tmp
user=www
group=www
var:customVar=customValue

Do not put spaces around =. Also all of these variables are optional.

By default, mud does not change user or group if not specified, passes /tmp as basepath to the (un)deploy, has an empty string as version and no custom variables. The default paths to the scripts are /usr/local/etc/mud/PROJECTNAME.deploy and /usr/local/etc/mud/PROJECTNAME.undeploy.

Multiple configurations

It's also possible to have several configuration files for one project. For example, you might want to run different steps with different users. In order to do that, create a directory with the same path than if you had one configuration file but without the extension. In this example, it should be /usr/local/etc/mud/my-app. Mud will read all the files finishing with .conf in the directory and "run" them in alphabetical order so it's a good idea to prefix them as in 10_some_step.conf.

Note that if a .conf file exists, the directory will be ignored.

Custom variables

Custom variables specified with var:myName=myValue are set as environment variables when running the scripts. The last occurence of a variable assignment wins. In the following example, EDITOR will be set to emacs.

var:EDITOR=vim
var:EDITOR=emacs

Options and arguments

They are four available commands: deploy, undeploy, rollback and show-history.

You can have more information about options and arguments by typing mud --help or mud COMMAND --help for more specific information.

(Un)deploy scripts

The scripts are passed the project name, the version and the base path as arguments and have the environment variables set according to the configuration and --var options.

They should return an exit code of 0 in case of success and anything else otherwise.

Production and security

Mud is aimed to be used by root as well as unprivileged users to deploy applications: you might want your build system to be able to deploy the program without having access to this part of the system though. In order to achieve this, you can give sudo access to your CI user (say you use Cookhouse and the user is _cookhouse) and another user j.smith with a configuration like the folowing in /etc/sudoers. (Use visudo!)

User_Alias DEPLOYERS = _cookhouse, j.smith
Host_Alias WEBSERVERS = www.website.com, staging.website.com

DEPLOYERS WEBSERVERS = NOPASSWD: /usr/local/bin/mud

IMPORTANT: Mud prevents the user to choose a configuration file outside of the configuraton directory. You need to make sure that this directory and its files are NOT world-writable. An malicious attacker would be able to execute arbitrary code as root on that system.

thoferon / mud