Working With GIT - Conygreneueda.conygre.com/citi/content/infrastructure/GIT.pdf · $ git push To...

Copyright 2014 TPS Services Ltd

A user experience

Working With GIT


Content● What is source control?

● Why GIT?

● GIT architecture

● Connecting to GIT

● Creating a repository

● Adding and removing files

● Commitment

● Conflicts

● Being available (push/pull/fetch)

● Versions (branching)

● Tagging

● Getting information


What is source control?● Keep track of code changes

● Revert back to working code quickly

● Resolve coding disputes

● Version control

● Central repository of everything code based

● Prevent accidental overwrites

● Enable developers to work on same project

● And/or code simultaneously


Why GIT● Many tools available

– Subversion, Perforce, CVS, RCS

● These require network connectivity

● GIT is distributed

– Each user has own copy of repository

– Can commit changes locally

– No immediate network required

● Merge back to main repository

– Network required


GIT Help● On line help available

http://git-scm.com/docs/


GIT Architecture● Server/client

● Roll your own solutions require

– Ssh and or web server

– File storage

– Authentication mechanism

● Fully distributed

– Any failure of server allows client to copy back

● Data stored like snapshots

– Reference to all your files at that point in time

– .git is the repository


GIT Architecture

REPO

Developers

GIT Server

REPO

REPOREPO


GIT Local

http://git-scm.com/book/en/v2/Getting-Started-About-Version-Control


GIT servers● Github

– Cloud solution

● Windows

– Bonobo Git Server● Requires IIS and MVC4 runtime

● Linux

– Configure sshd

– Configure a web server● Apache


GIT Clients● Store local copies of repository

● Enables developer to work offline

– Local commits stored in history

– Git deals with histories when pushed

– Git deals with conflicts on push

● Windows

– GITBash

– Tortoise GIT requires GITBash

● Linux

– Native git command line client


Command line GIT● Simple and easy to use

● Syntax

git <action> [<args>]


GIT attributes● Enables GIT to remember settings

● Global applies to all your repositories

– Stored in $HOME/.gitconfig

● Local specific to a repository

– Set this type within the desired repository

– GIT_DIR/config

git config [--global] <attribute> <value>

http://git-scm.com/docs/git-config


Setting GIT attributes● Git needs to identify you

– User name

– Email address

● Cache password

git config --global user.name “Steve”

git config --global user.email “[email protected]”

git config --global credential.helper 'cache --timeout=3600'

Default is 15 minutes if not specified

git config --global diff.external /usr/bin/diff


GIT Config file example

[user]email = [email protected] = Steve

[credential]helper = cache –timeout=3600

[diff]External = /usr/bin/diff

● File content

● List attributes

git config --list


Exercise● Add the following global information

– Email = gituser1@localhost

– Username = Example User

● Set the credentials cache to 4 hours

● Which file is this information stored in?

● List the configuration with a git command


Solution● Add the following global information

– Email = gituser1@localhost● git config --global user.email 'gituser1@localhost'

– Username = Example User● git config --global user.name 'Example User'

● Set the credentials cache to 4 hours

– git config --global credential.helper 'cache --timeout=14400'

● Which file is this information stored in?

– $HOME/.gitconfig

● List the configuration with a git command

– git config --list


Connecting to GIT● Requires user account to connect

● Requires hostname or up address

● Requires protocol (ssh or http[s])

● Commands that connect

– init

– push

– clone

– pull

– fetch


GIT URLs● Git allows many connection types

– ssh

– git

– http[s]

– ftp[s]

– rsync

[ssh://][user@]host.xz[:port]/path/to/repo.git/

git://host.xz[:port]/path/to/repo.git/

http[s]://host.xz[:port]/path/to/repo.git/

ftp[s]://host.xz[:port]/path/to/repo.git/

rsync://host.xz/path/to/repo.git/


Creating a repository● Must be done on the server

– Either through ssh or web interface

● With ssh

– Log on to server

– Change to the git repository directory

– Make a new directory● mkdir /git/projects/testone.git

● cd /git/projects/testone.git

– Initialise the repository● git init --bare

● On your workstation

– git clone <repository details> [optional local directory]● e.g. git clone [email protected]:projects/testone.git

● e.g git clone http://myhost.local/projects/testone.git

mailto:[email protected]


Adding A Repo In GitHub● Log in to your github account

● Select the + to add a repository


GitHub New Repo Form


Cloning● How you connect to a GIT repository

● Makes a local copy of repository

– Allows you to work off line from real repository

– All commits done locally

● Syntax

git clone <repositoryURL> [<local directory>]

Enables multiple copies of repository locally

Use the relevant URL for connection to your repository


Cloning Example● Get first version

● Another copy

git clone [email protected]:/project/testone.git

Creates testone directory

git clone [email protected]:/project/testone.git anothertest

Creates anothertest directory

Directories created with latest versions at time of clone

http://git-scm.com/docs/git-clone

mailto:[email protected]


Exercise● Clone the following repositories

– All repositories are in the directory git

– puppet using web url with host on port 8080

– crm using git

– cadcam using ssh and user gituser


Solution● Clone the following repositories

– All repositories are in the directory git

– puppet using web url with host on port 8080● git clone http://localhost:8080/git/puppet.git

– crm using git● git clone git://localhost/git/crm.git

– cadcam using ssh and user gituser● git clone gituser@localhost/git/cadcam.git


Managing files● GIT is for team work

– You can edit the files as though they were your own

– All members can add, remove and change files

● Operations

– add● Puts files in staging area

– rm● Tell Git you wish to remove a file from repository

– mv● Tell Git you wish to rename a file

git add file1 [file2 [filen]] git add * git add .

git rm file1 [file2 [filen]] git rm \*

git mv source newName


What have I changed?● Use the status command

● A new file added

● Modified file

git status

$ git statusOn branch masterChanges to be committed: (use "git reset HEAD <file>..." to unstage)

new file: README

$ git statusOn branch masterChanges to be committed: (use "git reset HEAD <file>..." to unstage)

modified: README


Nothing changed

$ git statusOn branch masterYour branch is up-to-date with 'origin/master'.

nothing to commit, working directory clean


Be committed● You need to be committed

– Changes saved when you commit to the repository

– Allows you to roll back to older versions

$ git commit -m 'J183: Some useful comment'[master 463dc4f] J183: Some useful comment 1 files changed, 2 insertions(+) create mode 100644 README

Short-hand comment with -m

If no -m you will be placed in default text editor to create a comment


By-pass staging● Add and commit in one go

– For existing files only

● Specify file names with commit

● Syntax

$ git commit -m 'updated' README [master c2b1bbf] updated 1 file changed, 1 insertion(+)

git commit -m 'comment' file1 [file2 [filen]]


Conflicts● Same file changed on local repository

– More than 1 person working on same file

– Both commit locally

– First push wins● Subsequent pushes require resolution of conflicts

$ git pushTo [email protected]:project.git ! [rejected] master -> master (fetch first)error: failed to push some refs to '[email protected]:project.git'hint: Updates were rejected because the remote contains work that you dohint: not have locally. This is usually caused by another repository pushinghint: to the same ref. You may want to first integrate the remote changeshint: (e.g., 'git pull ...') before pushing again.hint: See the 'Note about fast-forwards' in 'git push --help' for details.


Conflicts (2)● So we pull as we are told

$ git pullremote: Counting objects: 5, done.remote: Total 3 (delta 0), reused 0 (delta 0)Unpacking objects: 100% (3/3), done.From myhost.local:project d1b896f..c2b1bbf master -> origin/masterAuto-merging READMECONFLICT (content): Merge conflict in READMEAutomatic merge failed; fix conflicts and then commit the result.


What are the changes?● git diff

$ git diff READMEdiff --cc READMEindex 4275b69,71b5210..0000000--- a/README+++ b/README@@@ -1,2 -1,2 +1,6 @@@ ladjask++<<<<<<< HEAD +alksdsdjlk++=======+ sakjdaldkakdj++>>>>>>> c2b1bbfc909fac8e0b0eea7a3ff1f156a187d8ba

In central repositoryIn your file


Status of changes

$ git statusOn branch masterYour branch and 'origin/master' have diverged,and have 1 and 1 different commit each, respectively. (use "git pull" to merge the remote branch into yours)

You have unmerged paths. (fix conflicts and run "git commit")

Unmerged paths: (use "git add <file>..." to mark resolution)

both modified: README

no changes added to commit (use "git add" and/or "git commit -a")


Example Merge

$ vi README$ git commit -m 'changed' README$ git push

USER 1

$ vi README$ git commit -m 'changed' README$ git pushTo [email protected]:project.git ! [rejected] master -> master (fetch first)….$ git pull$ git mergetool --tool=meld

USER 2

$ git commit -m 'new comment'$ git push


Merge tools for GIT● Linux

– meld

● Windows

– winmerge

● Mac

– Kaleidoscope

– DeltaWalker

– Araxis Merge

– FileMerge

● All platforms

– kdiff3


Cheating merge● A manual change process

– Copy your files that are conflicting to new location

– Remove your local directory

– Clone the repository

– Add your changes to the files

– Commit then push


Availability● Making your changes available to your team

– Push regularly

● Getting your teams changes

– Pull frequently

● Provides an element of high availability

● Commands

– push = place your local changes to central repository

– pull = get updates from central repository into local

– fetch = like pull but no automatic merge


Updating● Fetch

– Pull but no merge

– File remains unchanged

$ git fetchremote: Counting objects: 5, done.remote: Total 3 (delta 0), reused 0 (delta 0)Unpacking objects: 100% (3/3), done.From myhost.local:project dcf1d25..523cd06 master -> origin/master

$ git merge origin/masterUpdating dcf1d25..523cd06Fast-forward README | 1 + 1 file changed, 1 insertion(+)


Checking before merging● Once fetched check difference

● git diff

$ git diff master origin/masterdiff --git a/README b/READMEindex 0995e88..90e0a63 100644--- a/README+++ b/README@@ -2,3 +2,4 @@ ladjask 434444 alksdjask 1111+laksdjlaskdj

Differenced line

From central repo

From local


Git diff new file● GIT fetch has new files

– Use git diff to see

$ git diff master origin/masterdiff --git a/newone b/newonenew file mode 100644index 0000000..fbba1e9--- /dev/null+++ b/newone@@ -0,0 +1 @@+laksdjasjd

New file and datain central repo

No file in local


Multiple file change

$ git diff master origin/masterdiff --git a/README b/READMEindex 90e0a63..9bffd37 100644--- a/README+++ b/README@@ -3,3 +3,4 @@ ladjask alksdjask 1111 laksdjlaskdj+55555diff --git a/newone b/newoneindex fbba1e9..8bd840f 100644--- a/newone+++ b/newone@@ -1 +1,3 @@ laksdjasjd+111112+22222


Magic fetch● Pull does all the magic

– Fetches and merges in one go

– Pull before you start making changes

– Always ensure you are working on the lated

– Pull regularly

– Cannot resolve merge conflicts

$ git pullremote: Counting objects: 7, done.remote: Compressing objects: 100% (3/3), done.remote: Total 4 (delta 0), reused 0 (delta 0)Unpacking objects: 100% (4/4), done.From myhost.local:project 8172e81..3781012 master -> origin/masterUpdating 8172e81..3781012Fast-forward README | 1 + newone | 1 + 2 files changed, 2 insertions(+)


Giving back● Push to let everyone else see your changes

– Must have a commit list first

$ git pushCounting objects: 7, done.Delta compression using up to 8 threads.Compressing objects: 100% (3/3), done.Writing objects: 100% (4/4), 362 bytes | 0 bytes/s, done.Total 4 (delta 0), reused 0 (delta 0)To [email protected]:project.git 8172e81..3781012 master -> master


Branching● What is branching?

– Diverge from the main line of work

– A way of keeping different versions● Project wide

● Local user – trying things out

● What can we do with branching?

– Have master as the stable release

– Use branches for● Release versions

● Test, before merging to another branch

● Research or trying something out from other branches

● Keep parallel versions running

– e.g. Support Android 2 on one branch and 4 on another, but sharing original code before branch

http://git-scm.com/book/en/v1/Git-Branching-What-a-Branch-Is


Branching quick view

git checkout testing

Commit on testing branch

New change on master


How To Branch● Basic example

– Git web site has simple example● http://git-scm.com/book/en/v2/Git-Branching-Basic-Branching-and-Merging

● Creating a branch and make it active

● Creating a new branch

git checkout -b newBranchName

git branch newBranchName

http://git-scm.com/book/en/v2/Git-Branching-Basic-Branching-and-Merging


Developing on a branch● Multiple users can develop on the same branch

– Branch must be pushed to the remote repository

– Other users checkout the branch

– Work on branch as normal

● Example

User1 session:$ git checkout -b v2Switched to a new branch 'v2'$ git branch master* v2# Make updates to file called codefile$ git add codefile$ git commit -m 'new version for codefile' codefile# Make your branch available to public$ git push origin v2

User2 session:$ git branch* master$ git checkout v2$ git branch master* v2


File on branches● Example

$ git branch* master v2$ cat codefile# This is version 1 of the file# Created in the master branch of the project$ git checkout v2Switched to branch 'v2'$ cat codefile # This is version 1 of the file# Created in the master branch of the project# This is added on branch v2$ git checkout masterYour branch is up-to-date with 'origin/master'.$ cat codefile# This is version 1 of the file# Created in the master branch of the project


Merging branches● Bring changes into continual development

– Local branch to public version branch

– Version branch to master

# Changes made on codefile in v2 branchgit commit -m 'Merging to master'[v2 fff84dd] Merging to master 1 file changed, 1 insertion(+)$ git push origin v2Counting objects: 7, done.Delta compression using up to 4 threads.Compressing objects: 100% (3/3), done.Writing objects: 100% (3/3), 401 bytes | 0 bytes/s, done.Total 3 (delta 0), reused 0 (delta 0)To git@localhost:project.git e65f543..fff84dd v2 -> v2

$ git checkout masterSwitched to branch 'master'$ git merge v2Updating c6d2ab2..fff84ddFast-forward codefile | 2 ++ 1 file changed, 2 insertions(+)


Merge one file change● Merge only changes in one file from a branch

# Changes made on the v2 branch and pushed$ git checkout masterSwitched to branch 'master'Your branch is up-to-date with 'origin/master'.$ git checkout --patch v2 codefilediff --git b/codefile a/codefileindex cdd53a4..936993f 100644--- b/codefile+++ a/codefile@@ -2,3 +2,4 @@ # Created in the master branch of the project # This is added on branch v2 # A change on v2 which will merge back to master along with the rest+we won't merge this change thoughApply this hunk to index and worktree [y,n,q,a,d,/,e,?]? y


Branching with Puppet● Puppet is a good example of using branches

– Environments● Development

● Test

● QA

● Production

● Each environment a branch

● Changes merged from

– Dev to Test end of sprint

– Test to QA if all unit tests pass

– QA to Prod if integration tests pass

● Great for use with tools like Hudson/Jenkins

● Could also consider tags too


Tagging● 2 types

– Lightweight● Pointer to specific commit

● Tracks tag names only for simple ref

● Great for checking out previous locations by name

– Annotated● Full object store

● Good for marking release points

– Can use tag to pull code into another environment● Continue to develop without affecting tag

http://git-scm.com/book/en/v2/Git-Basics-Tagging


Tag commands● git tag

– List all tags

● git tag tagName

– Create a lightweight tag

● git tag -a tagName -m comment [commitChecksum]

– Create annotated tag

● git show tagName

– Show tag detail

● git push origin tagName

– Make tags public


Example# Code development# commits, merges, etc all made# Code passes all tests# Current sprint signed off and code good$ git tag -a v1.1 -m 'Release Jira1234'$ git push origin v1.1Total 0 (delta 0), reused 0 (delta 0)To git@localhost:project.git * [new tag] v1.1 -> v1.1

$ git show v1.1commit fff84dd4f9de21749f7899e97989f6044d5687f2Author: Steve Shilling <[email protected]>Date: Sun Nov 9 20:02:17 2014 +0000 Merging to masterdiff --git a/codefile b/codefileindex 636da7f..cdd53a4 100644--- a/codefile+++ b/codefile@@ -1,3 +1,4 @@ # This is version 0.1 of the file # Created in the master branch of the project # This is added on branch v1+# A change on v1 which will merge back to master along with the rest


Cloning Tag Code● Need to clone release only

– e.g. releasing to production

● Don't want any other part of the branch

$ git clone --branch tagname url [localdir]

$ git clone --branch release3 git@localhost:project.git rel3


Tagging Flow

dev1 dev2

Master branch

local local

commit commit

Dev branchpush

Code freeze

git tag -a v0.1 -m 'Release 0.1 ref jira010'

Merge if tests pass and signed off

Prodrepo

git clone --branch v0.1 [email protected]:project.git proj-v0.1

git clone --branch v0.2 [email protected]:project.git proj-v0.2

Tag v0.2


Information Commands● git log

– Shows commit logs

– http://git-scm.com/docs/git-log

● git rev-list

– Lists commit objects in reverse date order

– http://git-scm.com/docs/git-rev-list

● git diff

– Show differences between commits, commits and working tree and others

– http://git-scm.com/docs/git-diff

● git blame

– Show revisions and author line modifications

– http://git-scm.com/docs/git-blame

● git show

– Show different object information

– http://git-scm.com/docs/git-log


References● http://git-scm.com/docs

● http://gnuradio.org/redmine/projects/gnuradio/wiki/DevelopingWithGit

● http://git-scm.com/book/en/v1/Git-Branching-What-a-Branch-Is

●

Working With GIT - Conygreneueda.conygre.com/citi/content/infrastructure/GIT.pdf · $ git push To...

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Transcript of Working With GIT - Conygreneueda.conygre.com/citi/content/infrastructure/GIT.pdf · $ git push To...