Git/Gerrit Workshop
===================
:copyright: SAP AG
:backend: slidy
:max-width: 45em
:data-uri:

Agenda Day 1
------------
- Introduction
- Basic Git Concepts
- Exercises: Local Development, Branches
- Merge & Rebase
- Exercises: Merge, Rebase, History Rewriting

Agenda Day 2
------------
- Push
- Gerrit Concepts
- Exercises: Code Review with Gerrit
- Q & A

include::distributed-versioning-systems-1.txt[]

include::distributed-versioning-systems-2.txt[]

include::git.txt[]

Git at SAP
----------
Project using Git:

- HANA, JPaaS, Avatar, ...

Product Standards

Committer/Contributor Model

- SAP-UI5, Java Server

Centrally hosted and operated

Git/Gerrit Team

Git/Gerrit Team
---------------
Support

- mailing list, bug trackers

Training

Hosting

- central Gerrit server with backup

Development of Tools

- contribution to EGit, JGit, Gerrit

Basic Git Concepts
------------------

Making Changes
--------------
Structure in the file system

- one working tree per repository
- `.git` folder is the *version database*
- files/folders next to `.git` folder are the *working tree*

image:../../img/git-fs-layout.png[]

Making Changes
--------------
Checkout

- populate the working tree with the commit you want to start working from

image:../../img/git-checkout.png[]


Making Changes
--------------
Just start doing your changes

- modify, add, delete files

Tell Git which changes you intend to commit:

	git add <file-name>

EGit helps by auto-detecting changed files

Committing Changes
------------------

	git commit

- provide a commit message
- commit represents a version of the complete repository
- each commit is identified by a globally unique ID (SHA1)

Commit Message
--------------

- first line is header
- separated by a blank line follows the body
- last paragraph is for meta dat in the `key: value` format

----
First line is header, shall be shorter than 70 chars

Separate the body from the header by an empty line. The commit message
should describe why you are doing the change. That's what typically helps
best to understand what the change is all about. The details of what you
changed are visible from the file diffs.

Body can be as many paragraphs as you want, shouldn't exceed width of 80
chars. This helps command line tools to render it nicely. Paragraphs are
separated by empty lines.

Bug: NGP-123 is rendered as a hyperlink to jtrack
----

Making Changes
--------------
Commit

- create a new commit in the repository with the changes done in the working
  tree

image:../../img/git-commit.png[]

Staging Changes - Git Index
---------------------------
*Index* or *Staging Area* is where the next commit is prepared

image:../../img/git-add-to-index.png[]

Commits
-------
- commit history
	- B is successor of A
	- C is successor of B

image::../graph/git/bin/abc.png[align="center"]

Branches
--------
- branch is a named pointer to a commit, example: `master`
- full name is `refs/heads/master`
- the commit command moves the pointer

image::../../img/git-commit-moves-branch.png[align="center"]

Branches
--------

- branch can also be moved "manually" to any commit

	git reset

image::../../img/git-reset-branch.png[]

Branches
--------

- what happens on next `git commit`?
- `C` and `D` continue to exist but they are not in the history of the master
  branch

image::../../img/git-commit-after-reset.png[]

Branches
--------

- usualy there are many branches in a Git repository
- branches can also be deleted

image::../../img/git-many-branches-and-deletion.png[]