2016 MacAdmins - Using Git for Automation and Collaborationmacadmins.psu.edu/.../2016/...Git-for-Automation-and-Collaboration.pdf · USING GIT FOR AUTOMATION AND COLLABORATION

U S I N G G I T F O R A U T O M AT I O N A N D C O L L A B O R AT I O N

J U S T I N E L L I O T T - M A T T H A N S E N P E N N S TA T E U N I V E R S I T Y

A G E N D A

• Version control overview

• Introduction and basics of Git

• Advanced Git features

• Collaboration

• Automation

V E R S I O N C O N T R O L

W H AT I S I T ?

• Manages changes and versions of files

• Also known as:

• Source Code Management (SCM)

• Version Control System (VCS)

• GitHub is a hosting service that uses Git

W H Y U S E I T ?

• Reduces risk and enables you to experiment with code

• Agility

• Flexible workflows

• Quicker deployments

• Automate updates

W H Y U S E I T ?

• Helps with documentation

• Collaboration with others

• Contributing to open source projects

• Modifying a project for your own use

G I T I N T R O D U C T I O N

W H Y G I T ?

• The current de facto standard for source code management

• Easy to learn, quick to start!

• Very powerful and extensive

G I T O V E R V I E W

• Extremely fast

• Excellent data integrity

• Git checksums everything (SHA-1)

G I T O V E R V I E W

• Distributed

• All clients have the full repo

• Backups are everywhere

• Local repo updated before remotes

• When available, push updates to remote

G I T T E R M I N O L O G Y

• Repository

• Local

• Remote

• Working Directory

• Commit

G I T I N S TA L L AT I O N & C O N F I G U R AT I O N

H O W T O I N S TA L L G I T

• Embedded with many Git GUI Apps

• Included with XCode

• Download from http://git-scm.com

• OS X: Terminal.app

• Windows: Git Bash

• Linux: Terminal

• OS X: MacPorts and HomeBrew

G I T C L I E N T A P P S

• http://git-scm.com/downloads/guis

• GitHub Desktop

• https://desktop.github.com

• SourceTree

• https://www.sourcetreeapp.com

R E V I E W I N G D I F F S

• Very easy to view with GitHub Desktop and Web

• External diff apps

• FileMerge

• Kaleidoscope

G I T H U B D E S K T O P

• Simplifies the complex Git tasks

• Integrates well with GitHub hosting service

• Easy to start with

• Limited feature set (by design)

D E M O : G I T H U B C O N F I G

C O N F I G U R I N G G I T O N T H E C L I

• Git GUI clients handle it for you, or for the CLI fans …

• $ git config

• Contains items such as name, email, editor, diff tool

• Critical for collaboration

D E M O : G I T C O N F I G C L I

https://asciinema.org/a/anjsg2tmlwul6j3ahizgl98ie

F U N D A M E N TA L S

R E P O F I L E C L A S S I F I C AT I O N S

• Tracked

• Ignored

• Untracked

T R A C K E D F I L E S TAT E S

• Modified

• Staged

• GitHub Desktop shows as checkboxes

• Committed

C R E AT E A R E P O

• Create new empty project repository

Working Directory

• Add (stage) files for the next commit

A D D F I L E S T O T H E R E P O

Working Directory

Staging Areaadd

C O M M I T F I L E S T O R E P O

Working Directory

Staging Areaadd

Repositorycommit

• Save staged files to the project repository

C O M M I T S

• Saves file changes to the repo

• Each commit should encapsulate a single fix*

• Commit often - You will thank yourself later!

• Or else … Larger changes are much harder to pick apart and revert back to.

I G N O R I N G F I L E S / D I R E C T O R I E S

• Why? • What? • How? • Scope

• Single Project Repo • All Repos ( Global ~/.gitignore_global file )

• Recommended to create ignore file as first step

C O M M I T H I S T O R Y L O G S

• Review history of commits to repo

• Documents changes over time

• Extremely helpful for your future self and others

D E M O

• Create repo

• Create files

• Show status

• Ignore file(s)

• Commit git ignore file

• Initial commit of file

• Modify same tracked file

• View diff of file changes

• Commit the file

• Review history log

• Revert to previous commit

• Review history log

B R A N C H E S

B R A N C H E S

• Provide separate paths of code development

• When should they be used?

• Others to help test before merged to master

• “master” is the default branch

• Great for vetting major changes, for others to review

• Many workflow methods out there (ie, GitFlow)

B R A N C H W A L K T H R O U G H

M 1

First Commit


M 1

New Branch

B 1


M 1

B 1 B 2

Second Branch Commit


M 1

B 1 B 2 B 3

Third Branch Commit


M 1

B 1 B 2 B 3 B 4

Fourth Branch Commit


M 1

Merge Branch To Master

B 1 B 2 B 3 B 4

M 2

(Branch Deleted

After Merge)

G I T ' S " H E A D " R E F E R E N C E

• Reference pointer to a commit

• “Detached HEAD” warning

• What does it mean?

• When does this occur?

• What should I do?

• Have code changes? Branch!

B R A N C H W O R K F L O W S

• GitHub Flow

• Atlassian’s List

• Centralized

• Feature

• Git Flow

• Forking

R E M O T E S

R E M O T E S

• Local repo on your client only

• Remote is a Git host to push to

• You clone from remote(s)

• ie. GitHub, BitBucket

• First remote is called “origin”

• Avoid changing the remote name, some GUI Apps look for it

R E M O T E R E P O S

• Network Protocols

• HTTPS

• SSH (Keys)

• Git Protocol (daemon)

S E L F - H O S T E D R E P O S E R V I C E S

• SSH

• Enable SSH, create “bare” repository on server

• % git init --bare --shared

• Atlassian Stash

• Enterprise GitHub

• GitLab

H O S T E D R E P O S E R V I C E S

• GitHub, BitBucket

• SourceRepo, Assembla

• GitLab

• git.psu.edu for Penn Staters (runs on GitLab)

• And many more …

G I T W O R K F L O W S TA G E S

Working Directory

Staging Areaadd

Repositorycommit

Remotepushpull

C L O N I N G

• Copies repo from remote

• Repo includes entire project

P U S H I N G

• Saves commits to remote server

• Pushes active branch that you’re on

F E T C H I N G

• Updates repo status of remote

• Local repo files are not changed

• Always fetch or pull before pushing to remotes!

R E M O T E S - D O ' S A N D D O N ' T S

• Do...

• Always fetch or pull before making changes

• Otherwise you will need to merge or rebase your changes

• Don't...

• Make changes to local repo before fetching/pulling, or else create a new branch first

• OR stash the files first

R E M O T E S D E M O

• Add local repo to GitHub Desktop

• Publish to GitHub

• View new remote host via “git remote -vv”

• View tracking branch(es) via “git branch -vv”

• Local branches track remote branches

• Commit first to local, then push to GitHub

• Create README.md file on GitHub, Pull

C O L L A B O R AT I O N

E T I Q U E T T E

• Pull Request vs. Feature Requests

• Read the project's docs and guidelines first

• Start with simple changes to learn processes

• Avoid pull requests on pull requests

• Instead, provide feedback to author of pull for additional fixes or suggestions

E T I Q U E T T E

• Commit Messages

• Keep them small, clear and descriptive

• Remember others need to understand them

• Stick to the project's coding styles and conventions

• Follow or establish team decided branch workflow

• Be nice!

C R E AT I N G A P U L L R E Q U E S T

Their Remote Repo

Your Remote Repofork

Local Repositoryclone/pull

Working Copy

commit

Pull Request

mergepush

Discussion

Contributor

G I T H U B P U L L R E Q U E S T

R E C E I V I N G A P U L L R E Q U E S T

• Discuss and gather feedback


• Squash & merge or Merge commit


• Checkout and test

A U T O M AT I O N

I N T E G R AT I O N S

• Automatic emails

• Push notifications

• Slack Channels, IRC, Twitter, HipChat, etc.

• Methods

• WebHooks

• Agents / Runners

• Polling

A U T O M AT I O N T O O L S

• Scripts

• launchd, cron to automate git pulls

• AutoPkgr schedule for autopkg recipe repos

• Continuous Integration

• Jenkins, Atlassian Bamboo, GitLab

• Travis CI

W E B H O O K S

• Receive event notifications between multiple systems

• commit, push (tag or branch), releases, issues, documentation updates, forks, etc.

• Useful for updating, notifying, building, testing, backing up, deploying

A U T O M AT I O N I D E A S

• Auto update servers (Web, etc.)

• Revert to previous commit

• Example

• Agent/Runner runs script after repo receives commit

• Automated testing, build and test products/recipes

A U T O M AT E D W O R K F L O W S

• Update server content from master branch

• Auto pull “ready for production” versions

• Track changes made on servers, switches

• .git folder security issue - be aware

C L C C A S E S T U D Y

autopkg

GitLab GitHub

BigFix

Jenkins

Slack

C L C C A S E S T U D Y

• Lessons Learned

• Use the tool that works best

• Keep it simple and robust

• Lots of notifications, categorized and specific

• Working with internal and external collaborators

• Leverage the features of Git - commits, events, builds

S U M M A R Y

L E S S O N S L E A R N E D

• Start small

• Pick just one project to manage with Git

• Use remotes when ready

• GitHub, BitBucket

• Your own SSH host


• Write good commit messages

• There will be a time when you need to search your commit messages and it will really help you out!

• Be nice to your future self.

• “Where / when / how did I fix that issue?”

• What’s for the release notes?


• Keep it simple

• Don't be afraid to experiment

• Automation and integrations are powerful

• Use them after you're comfortable with the basics

R E S O U R C E S A N D T R A I N I N G

• http://bit.ly/psumac-git-cs

• Official Git Site

• http://git-scm.com

• Git Cheat Sheets

• Git Pro Book

• bit.ly/psumac-nice-pulls

R E S O U R C E S A N D T R A I N I N G

• http://try.github.com - learn Git in 15 minutes!

• http://atlassian.com/git

• http://bit.ly/psumac-git-wf

• O’Reilly

• “McCullough and Berglund on Mastering Git”

Justin Elliott jelliott [at] psu.edu

@justindelliott

Matt Hansen hansen.m [at] psu.edu

@hansen_m

Feedback: https://bit.ly/psumac2016-91

Q & A