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An introduction to git
======================
You are probably familiar with the concept of a `version control system`
- a repository in which your source code is stored, which keeps track of
changes made to every file over time. You may be less familiar with the
concept of a *distributed* version control system. In the traditional
model, there is one central server holding a master version of your
software; each developer checks out software to their local machine,
makes changes to it, and commits it back to the server.
In a distributed version control system, there is no authoritative
server enforced by software. Each developer has their own repository;
there may be a master repository (in the case of Baserock, the Trove)
or indeed a series of repositories accumulating changes by various
developers to particular subsystems, as in the case of the Linux kernel,
but this is simply a matter of policy.
Because each developer has their own repository, they do not need
continuous network access to work, and because each developer has
a complete local copy of the whole codebase branches become very fast.
Consequently, git development revolves much more strongly than most
version control systems around a model of creating a temporary local
branch for a particular bugfix or feature, getting that branch to work
correctly, and then merging it into the upstream repository;
therefore, as well as fast branching it also has very powerful support
for merging.
Baserock is designed to take full advantage of this. The whole Baserock
system is stored in git. Making changes to your system involves
branching your system as a whole, making changes to the components
of Baserock you want to modify in a local branch in your local
git repositories, and eventually merging those changes into your
upstream repository. Part of Baserock's power is in its ability
to automate the process of branching every component in
your system as you work on them.
Apart from its suitability by design for such a development model,
and because of its scalability, we use git because it is by far the
most popular open source revision control system, making it easy
to incorporate many upstream components into Baserock; indeed,
upstream components not using git are converted to use git in
order that Baserock can be a homogenous whole.
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