Git

© 2010 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 1

Git Training & Support Doc.

Rajesh Tripurneni


PreReqs• If on StarOS machine add Git executable to your path

export PATH=$PATH:/auto/mitg-sw/tools/debian/git/bin

• Add your public key to Gitolite from a machine that has access to http://wwwin-mitg-releng.cisco.com

/auto/mitg-sw/oak/bin/git-request-access (git request-access)

• Verify your accessssh mitgscm@mitg-git info | grep perf | grep -v autotest


Basic Workflow• Create clone

Clones all branches but checks out only 1 at a time

• Make some changes

• Add changes to staging area (index)

• Commit changesSubmit changes for PRRQ review at this point

• Push changes to server*Git will notify you if you have to pull before push to get most recent changes and merge may be required$ git push

• Periodically update release file, commit, apply tag and push update from perftest-staging to perftest

Operation is restricted to authorized users


Branches• 3 Types

Topic

Local

Tracking

• Conventionsbitkeeper/.* : Bitkeeper imports

dev/.* : Development branches

merge/.* : Merge branches

jenkins/.* : Jenkins last good build branches

.* : Official Releng managed branches (e.g., master)

• Creating a dev branch$ git checkout –b dev/<some_name> <optional commit #/branch/tag>

$ git push –u origin dev/<some_name>

• Checking out a local branch$ git checkout <branch name>


Tags• Pointer to a commit to identify interesting state

Doesn’t move once applied

Can be simple or annotated

$ git tag (list)

$ git tag -a -m “Tag Message” <tag name>

• Doesn’t get pushed to server with regular ‘git push’$ git push --tags (push all tags)$ git push origin <tag name>

$ git push $REPO_URL <tag name>

• Branch data and tag data have to be pushed separatelyPushing tag will not update branch head with commits up through tag

• Script to update perftest-staging/bin/release and apply tag/auto/mitg-sw/tools/bin/git-tag-perf$ git tag-perf -t release-1.1.6


Hooks• Equivalent to BK triggers

• Clientpre-commit: Check for non-ascii filenames and merge markers left in files

commit-msg: Check for CDETS ID only on command line and add CDETS Headline if found

post-commit: Warn if no CDETS and suggest ‘git commit --amend’

post-checkout: Submodule processing

post-merge: Submodule processing

• Serverpost-receive: Calls cdets and email hooks on official branches only

post-receive-cdets: Add CDETS Enclosure for commits with CDETS in msg

post-receive-email: Send push notification to configured email alias

• Perftest BK triggers implemented by Releng as Gitolite access and push notification rules and new ‘git tag-perf’ script

Releng will maintain both of these


Cloning a Server Repository• Use MITG ‘git-ws’ script to clone your repository and set up client

side hooksSets required git configuration valuesCreates local cache clone if cloning to local diskPopulates clone with client hooks (equiv of bk triggers)

• Ignore ‘repository cache’ warning if cloning to non-local disk

• Clone from default branch (master)$ git ws qa/perftest-staging perftest-staging

• Clone from specific branch$ git ws --branch dev/docon_work qa/perftest-staging pfstage_docon_work

• Clone from tagNote: This will result in a detached head (no branch) which is ok if you do not intend to make changes$ git ws --tag release-1.1.5 qa/perftest perftest


Clone Status• To check status of your clone use ‘git status’

$ git status

Local commit

Staged for commit

Modified but not yet staged with ‘git add’

New file not yet versioned


Environment Setup• Bash Auto-completion

• Display branch in command line prompt

• Git ConfigurationGlobal (--global) vs. local

$ git config -l (list)

• Git Gui Edit Options

http://wikicentral.cisco.com/display/GROUP/Git+FAQ



Making Changes• To create new files or modify already-versioned files simply use

your favorite editor (files are writable by default)

• To change permissions use unix ‘chmod’ command$ chmod a+x sysEngine

• To create a symlink use unix ‘ln -s’ command

• To remove a file use ‘git rm <filename>’Removals are automatically added to staging by ‘git rm’

• To have Git ignore files you don’t ever want to version add then to .gitignore in the workspace root or at any level

.gitignore is versioned and accepts pattern matching

Releng to populate .gitignore with ‘bk ignore’ results from each repo

• Uncommitted changes are not associated with any branch

https://www.kernel.org/pub/software/scm/git/docs/gitignore.html




Staging Changes• Staging a change tells Git what to commit during the next

execution of ‘git commit’

• Also referred to as ‘Adding to the Index’ or ‘Adding to the cache’

• Can be done from command line$ git add <filename(s)>$ git add .

• Can also be done from ‘git gui’ by clicking on the file icon in ‘Unstaged Changes’ section


Committing Changes• Committing a change tells Git what will get pushed to the server during the

next ‘git push’ operation

• Can be done from command line$ git commit (will open an editor to type commit message)

$ git commit -m “<Commit Message>”

$ git commit --amend (amend commit message of last local commit)

• Can also be done from Git GUI by filling in Commit message Box and clicking ‘commit’ button.

• First time you attempt to commit from a StarOS machine with only a CDETS ID in the commit message you may see the following error. Simply try again and it should work from that point on.

The authenticity of host 'mitg-git.esl.cisco.com (<ip address>)' can't be established.RSA key fingerprint is <fingerprint>.Are you sure you want to continue connecting (yes/no)? yesERROR - Invalid CDETS id: <CDETS ID you used>Aborting commit due to empty commit message.


Diffs• Diff of modifications to working tree

$ git diff

• Diff of staged changes$ git diff --cached

• Diff of local commitsDiff commits reachable from local branch HEAD but not reachable from tracking branch

$ git diff origin/master..HEAD

• Diff of all local changes$ git diff origin/master

• To generate diff for PRRQ use git-review command or as of August 1 configure your PRRQ queue to use Git for SCM

git-review will not work from StarOS machines


Submitting Diffs to PRRQ• MITG-Releng git-review script does not work from StarOS

because it relies on PRRQ command line interface tools in /usr/cisco/bin

• The PRRQ Team should be releasing support for Git on August 1Auto-collect diffs from Git workspace based on supplied diff options

Queue must be configured to accept Git as ‘Source Code Management System Interface’

Side-by-Side display issues with IE

• When creating review or uploading new diff, auto-collect from Git


Merges• Pull history/commits from one branch into another

$ git checkout <dest branch>

$ git merge <src branch>

Resolve conflicts and ‘git add’/’git commit’

• Update master with latest changes from bitkeeper/master$ git checkout master

$ git merge bitkeeper/master

• Conflict resolution$ git config --global merge.tool tkdiff

$ git config --global mergetool.tkdiff.trustExitCode false

$ git mergetool <-y>


Viewing History• Command Line

$ git log <options>$ git log --grep=CSCub27153$ git log --since=14-MAY-2013$ git log --author=psanborn

• Showing specific commit information$ git show 4f17c57d724e6c59b9b82bc1425c3eaa1da3e0b3$ git show release-1.1.4$ git show release-1.1.4:bin/atsEngine.pl

• Graphically$ gitK

Available from ‘git gui’ via RepositoryBrowse <branch> files

• On the Server with GitWebhttp://mitg-git:15690/


Pushing to Perftest Production• qa/perftest is the production repository

• Authorized users periodically push from qa/perftest-staging to qa/perftest after updating bin/release file and applying a tag

$ git tag-perf -t release-1.1.6

• Master branch and latest tag push separately$ git checkout master

$ git push mitgscm@mitg-git:qa/perftest

$ git push mitgscm@mitg-git:qa/perftest <tag>

• Can opt to push both from Git GuiSelect Source BranchSelect ‘Arbitrary location’ and fill in mitgscm@mitg-git:qa/perftest

Select ‘Include tags’


Gotchas• Git GUI, gitk and tkdiff for mergtool require TCL 8.4 and StarOS

machines missing /usr/bin/wish8.4 will fail to invoke (e.g., smoke1-vm1, but wily1-vm1 works)

• Some StarOS systems produce ‘Protocol mismatch’ error attempting to get to releng website when running ‘git request access’

• Meld we built does not work on StarOS machines (use tkdiff instead)

• BK allows BK add in a git repositoryRetrieving file mistakenly removed with 'bk add'





Official Cutover from BK• Releng regularly importing changes from BK to Git repos

• Releng will maintain access rights to ‘master’ branch of each repository and to release tag creation in perftest and perftest-staging

Open RER of type ‘Other’ to request modifications of rights

• Bitkeeper perfinfra repository was locked on 7/26/2013Releng created ‘master’ branch from bitkeeper/master and made ‘master’ the default branch.

Permission to push updates to ‘master’ restricted to particular users

All new work in perfinfra should be performed in Git clone

• BitKeeper perftest and perftest-staging repositories will be locked August 16Until then, create ‘dev/’ branch to play on

Final import of BK perftest-staging into Git on Aug 16 after lock

Releng will update Git perftest from perftest-staging

Releng will create ‘master’ branch in perftest and perftest-staging from which all new work will be submitted

Releng will add .gitignore to perftest and perftest-staging


Resources• git help <command name>

• Cheat Sheet

• FAQ

• Using QA Repositories During Migration Period

• Pro Git Book

• Session 1

http://wikicentral.cisco.com/display/GROUP/MITG+Git+Cheat+Sheet+for+BitKeeper+users


http://wikicentral.cisco.com/display/GROUP/Using+QA+Git+Repositories+During+the+Migration+Period

http://progit.org/book/

Thank you.

Documents

Git