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Introduction to git administration
The document serves as an introduction to Git administration aimed at new administrators, discussing workflows, common tasks, and security considerations. It highlights the transition from traditional SCM systems to Git and provides guidance on best practices, such as effective migration strategies and the use of hooks for workflow management. Additionally, personal anecdotes from Git implementation are shared to illustrate the complexities and solutions encountered in real-world scenarios.
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Introduction to git administration
- 1. Introduction to GitAdministration For New Administrators Shawn Doyle ReleaseTEAM Inc sdoyle@releaseteam.com www.linkedin.com/in/releaseteam/ http://twitter.com/ReleaseTEAMInc
- 2. Premium SCM Consultingfirm since 1999 Focus on Software Configuration Management On site and remote consulting services – Build Automation – CM tool administration, customization, upgrades, migrations Classroom training / hands-on mentoring R e l e a s e T E ClearCase ClearQuest Jenkins Git RTC Build Forge SVN Jira Electric Commander Shawn Doyle - ReleaseTEAM
- 4. For theadministrator new to Git An overview of Git Workflows Common admin tasks Access control Triggers Stories from the trenches Subversion & Git Presentation Agenda Slide 4
- 5. So you noware a Git Admin
- 6. Git has sprungup in many organizations. Spreading like a wild fire from the development groups. – Developers want less restrictions to their productivity – SCM is always seen as a restriction and rarely a necessary one SCM admins are finding they need to support Git regardless of existing corporate standards. SCM admins need to find a way to control the chaos. Most commercial SCM tools now support Git as a client. Don’t panic Git is fun, powerful and it is the future. Subversion & Git Presentation Wait.. What? how did this happen Slide 6
- 7. DVCS – Learn thedifference Users – Training – Indulging the Git promoter(s) Many solutions to common problems – Authentication – Workflows – Multiple available UIs Cleaning up after user mistakes Subversion & Git Presentation What am I in for? Slide 7
- 8. 1. RTFM http://git-scm.com/book 2.Now that you read the Git book, go thru these tutorials 3. Watch these videos - Google Tech Talks Linus Torvalds on git Randal Schwartz on Git 4. RTFW https://git.wiki.kernel.org/index.php/Main_Page 5. Create a repo and start playing! Subversion & Git Presentation How I learned Git Slide 8
- 9. Tutorials http://try.github.io/levels/1/challenges/1 Code School https://www.atlassian.com/git/tutorial/git-basicsAtlassian's Git tutorial http://gitready.com/ Git Ready https://www.kernel.org/pub/software/scm/git/docs/everyday.html Everyday GIT With 20 Commands Or So Videos - Google Tech Talks http://www.youtube.com/watch?v=4XpnKHJAok8 Linus Torvalds http://www.youtube.com/watch?v=8dhZ9BXQgc4 Randal Schwartz Wiki https://git.wiki.kernel.org/index.php/GitCommunity|Git Community Wiki Subversion & Git Presentation Resources Slide 9
- 10. Git Overview Subversion &Git Presentation Slide 10
- 11. When coming fromanother SCM system to Git you need to shift how you think about how version control works. In a more classic SCM you think of it as a system that versions files in a tree or directory structure. Git is better thought of as a system that versions trees of files. Biggest Obstacle
- 12. Stores whole copiesof the repo – No file deltas – Entire tree is captured at each commit not just the files that changed, a snapshot of the repo Branches and tags – Are pointers to commits – Very fast and light weight Subversion & Git Presentation How Git Works Slide 12
- 13. Git is: – Powerful –Complex – Fast (local) – worthy contender to replace many commercial tools – the solution you are looking for Object Storage – Blobs – SHA1s or hashes – Trees Perl like syntax – ^ $ ~ … Subversion & Git Presentation Not Scared yet? Slide 13
- 14.
- 15. Centralized – Central repository FeatureBranch – Central repository + branching per features Gitflow – Branches per features, releases and bug fixes Forking – Distributed workflow Workflows
- 16. Uses a centralrepository – single point-of-entry for all changes – Everyone clones from the central repo – Everyone pull/pushes from the same repo Benefits – SCM Admin can put controls/triggers on the central repo – Security can be setup using tools like • Stash • Gitolite • Gitosis – SCM Builds and Deploys can be maintained from a clone of the central repo. Centralized
- 17. Development of featuresin isolated branches – Allows features to be developed independently As a feature is finished it is merged to the master branch Subversion & Git Presentation Feature Branch Slide 17
- 18. Branches are focusedaround releases Branches are also used for – Release – Integration or Test – Features Strict rules on how and when branches interact Subversion & Git Presentation Gitflow Slide 18
- 19. Repos are forkedper developer – Developers work in isolation One Repo is declared as the Official Repo – A Project Maintainer integrates the Repos – Developers sync with the Official Repo Subversion & Git Presentation Forking Slide 19
- 20.
- 21. What to Migrate?Snapshot in time or all history? – Push for converting a snapshot in time – If that fails, then try for a few key slices – Arguments • Why burden the new repo with all the history • Populating new workspaces will take longer • Leave old SCM system in a locked down state for reference – Refactoring • Always a good time to refactor when switching SCM system • Can cause headaches if under deadlines – Builds • How dependent were you on the old SCM for builds – Paths – Build tools (e.g. clearmake) – APIs, Libs Migration Considerations
- 22. Client and Serverconcepts Use a Client side hook for actions – Commit – Merge – Rebase Server Hooks – Notification – Rejecting Pushes Hooks need to be copied to the repos – Hooks are not part of cloning – Hooks do not get updated with pull/pushes In general, use hooks in Git to encourage workflow or for notifications. Do not rely on them to enforce security Subversion & Git Presentation Hooks Slide 22
- 23. Be Clever – Thereis no one way to provide Security – There is no single definition of Security SSH keys Git Repository Management – Stash – Gitolite – Github Triggers Subversion & Git Presentation Security Slide 23
- 24. Sometimes a userremoved something they didn’t mean to. The following commands are your friends when trying to figure out what to restore and from where. – Git log – Git relog – Git reset – Git update-ref Repos for backups – Create clones on a safe network disk – Pull to them once a day (or once a week) – Use them to recover files or as a reference Subversion & Git Presentation Recovering files Slide 24
- 25. Stories from thetrenches
- 26. Builds failed aftermigrating a project from ClearCase to Git – Dev group certain the migration to Git had failed – Build depended on a large number of sub directories to exist – Git does not add empty directories • It needs a blob to point to a directory for the directory to exist. – Solution was to initially add the missing directories • Created .temp files in each empty dir • This creates a blob and the directory is added to Git – Long term solution • Encourage them to fix their build Ant/Make files. Empty Directories
- 27. A user addedmultiple large files to his repo – Then committed them and pushed them to the central repo User removed them with ‘git rm –rf’ Why is this bad? – Clone commands went from seconds to 20 minutes Why? – Git didn’t remove the large files from the initial commit – Clone copies the entire repo locally, those files while no longer visible are still copied Solution – Git filter-branch – Git gc – Git prune Subversion & Git Presentation Slow Clones Slide 27
- 28. Client Requirements – Contractorslimited to sub dirs. – All files in a single Repo. Git by design – Does not preserve directory permissions – Hooks run before or after a Git command – Submodules don’t offer additional protections • Also broke the client single repo requirement Subversion & Git Presentation Directory Isolation Slide 28
- 29. Client workflow dependedon Tags Git Tags are not shared by default – Tags need to be explicitly; • Pushed to the remote • Pulled locally Solutions – Reevaluate Workflow – Share pull command with Tag name – Share Hash Subversion & Git Presentation Universal Tags Slide 29
- 30. Client wanted tocontrol who could create a local repo – Git is not designed to do this You can limit who can clone from a central Repo – Stash/Gitolite – SSH Keys Once a Repo is cloned – Nothing is stopping the user from cloning it again – They can allow others to clone Solution – Lock down who can push back to the central Repo Subversion & Git Presentation Controlling local repos Slide 30
- 31. Client wants toClone one subdir of a Repo – Build requires entire Repo – Deploy requires one sub dir – Build happens weeks before the deploy – Deploy wants a fresh Repo • Just build results and deployment script Solution – Submodules Subversion & Git Presentation Partial Clone Slide 31
- 32.