Git: Difference between revisions

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The bottom line is this: modern software development may take many "forms", but it usually boils down to [http://nvie.com/posts/a-successful-git-branching-model/ this]. Git enables such a branched workflow. That is why distributed version control in general, and git in particular, is the most widely adopted version control system for software development <ref>https://ianskerrett.wordpress.com/2014/06/23/eclipse-community-survey-2014-results/</ref>

~~{{Messagebox |~~

See [[Git/hacks]] for example commands

~~|type = normal~~

~~|text = See [[Git/hacks]] for example commands~~

}}

== Intro to Git ==

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Why do we have git? Because [http://whygitisbetterthanx.com Git is better than X] Now that we have the "My DVCS is better than your DVCS" argument out of the way, you can actually get some valuable insights from that website if you are interested in comparing Git with Mercurial, Bazaar, Subversion or Perforce. If I had to single out one primary advantage of Git, it would be that it actually features branching and merging.

Repo visibility is completely customizable, as are individual permissions to write to repos. I've installed a system called gitosis to handle the privileges through a special git repository. It uses Public Key cryptography rather than granting SSH accounts to everyone. This makes it really easy to do your work securely without even needing a password. For the curious, the actual mechanics of gitosis are detailed at [http://scie.nti.st/2007/11/14/hosting-git-repositories-the-easy-and-secure-way scie.nti.st]

Repo visibility is completely customizable, as are individual permissions to write to repos. I've installed a system called gitosis to handle the privileges through a special git repository. It uses Public Key cryptography rather than granting SSH accounts to everyone. This makes it really easy to do your work securely without even needing a password. For the curious, the actual mechanics of gitosis are detailed at [http://scie.nti.st/2007/11/14/hosting-git-repositories-the-easy-and-secure-way scie.nti.st]. Although that link may still work, there is also https://git-scm.com/book/en/v1/Git-on-the-Server-Gitosis.

{{Messagebox |

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git config --global diff.tool meld

git config --global --add color.ui true

# store password in memory for an hour

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

# recent packaged versions of git might be 1.8.3.1 (CentOS 7.4) whereas the current available is 2.15.1

# push.default is unset; its implicit value is changing in

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{{Highlight

|text = If you want to browse the git help in your browser (as above), then make sure you <code>sudo apt-get install git-doc</code> to get the HTML files}}

== Decentralized Workflow and Branching Model ==

Here's a good explanation on how most groups use Git in a successful branching model for development, "master", release branches, hotfixes, etc.

http://nvie.com/posts/a-successful-git-branching-model/

== Submodules ==

Using multiple repositories to compose your project. See https://git-scm.com/book/en/v2/Git-Tools-Submodules

git init myproject

cd myproject

git submodule add git@github.com:example.com/htdocs.git website

git submodule add https://gerrit.wikimedia.org/r/p/mediawiki/core.git mediawiki

git submodule add https://gitlab.com/Aranad/tools.git odtools

cd mediawiki/

git checkout REL1_31

cd ../

git commit -m 'initial commit'

git diff --submodule

git config --global diff.submodule log

git diff

git config -f .gitmodules submodule.mediawiki.branch REL1_31

git submodule update --remote

git status

git commit -am 'tracking REL1_31 in the mediawiki submodule'

git config status.submodulesummary 1

git log -p --submodule

cd mediawiki/

git submodule update --remote --merge

git config alias.sdiff '!'"git diff && git submodule foreach 'git diff'"

git config alias.spush 'push --recurse-submodules=on-demand'

git config alias.supdate 'submodule update --remote --merge'

</source>

== Tools ==

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* http://flavio.castelli.name/2007/09/04/howto_use_git_with_svn/

~~== Git Repo Hosting ==~~

It seems everyone uses GitHub these days (~8 million users, 20 million projects). It's not a bad solution, but there are some drawbacks, and whether you're just looking to host your own project or setup enterprise-wide git hosting, there are other ways to host your projects in Git. Let's take a look at some options.

~~<ol>~~

<li>'''GitHub''' can make it a bit easier for developers who are used to working with svn because they have 'built-in' [https://github.com/blog/1178-collaborating-on-github-with-subversion svn client] support.<ref>Anyone can use <code>git svn</code> and all the other built-in git subversion bridging commands, GitHub simplifies how to do it.</ref> GitHub [https://enterprise.github.com/home Enterprise] can be installed on your own servers. GitHub costs money for private repos.

<li>[https://about.gitlab.com/ '''GitLab'''] is the "popular" alternative to GitHub that comes in "Community", "Enterprise" and "Cloud" versions. They say it's "[https://about.gitlab.com/better-than-github/ better than GitHub]" One nice thing that I note is that they've integrated git-annex for large binary support. This is a nice plus. (I've personally used git-annex as a file backup system -- like DropBox. In my case, it was to make backups of UbuntuOne when that service was discontinued.) You can install GitLab in minutes on your own server. It's costs if you want the [https://about.gitlab.com/features/#compare Enterprise] version.<li>'''GitBlit''' is "a pure Java git server that just works". It's a "true" open source project run by [https://www.linkedin.com/pub/james-moger/8b/3a3/65b James Moger] and scores of other contributors. GitBlit is self-hosted, so you can get a feel for it quickly by looking at the projects own [https://dev.gitblit.com/ source code]. It does have some nice [http://gitblit.com/features.html features].

The current Wikimedia Ops team is using [http://gitblit.com/ Gitblit] to drive https://git.wikimedia.org/ Gitblit is an open-source, pure Java stack for managing, viewing, and serving Git repositories.

It's designed primarily as a tool for small workgroups who want to host centralized repositories. It comes in two options: GO is an integrated single stack solution so you can really get up and running in no time flat; and there is a WAR version (assumes you already have a servlet container like Jetty or Tomcat.) Gitblit requires a Java 7 Runtime Environment (JRE) Gitblit comes with a lot of [http://gitblit.com/features.html features]

~~<li>[http://gitolite.com/gitolite/index.html gitolite] is similar to the now defunct '''gitosis'''.~~

~~</ol>~~

== Background ==

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Only in /var/www/drupal/sites: www.example.org

</pre>

== Git Repo Hosting ==

See [[Git repo hosting]]

== Building a Git server ==

@@ Line 3: / Line 3: @@
 The bottom line is this: modern software development may take many "forms", but it usually boils down to [http://nvie.com/posts/a-successful-git-branching-model/ this].  Git enables such a branched workflow. That is why distributed version control in general, and git in particular, is the most widely adopted version control system for software development <ref>https://ianskerrett.wordpress.com/2014/06/23/eclipse-community-survey-2014-results/</ref>
-{{Messagebox |
+See [[Git/hacks]] for example commands
-|type = normal
-|text = See [[Git/hacks]] for example commands
-}}
 == Intro to Git ==
@@ Line 14: / Line 11: @@
 Why do we have git?  Because [http://whygitisbetterthanx.com Git is better than X]  Now that we have the "My DVCS is better than your DVCS" argument out of the way, you can actually get some valuable insights from that website if you are interested in comparing Git with Mercurial, Bazaar, Subversion or Perforce.  If I had to single out one primary advantage of Git, it would be that it actually features branching and merging.
-Repo visibility is completely customizable, as are individual permissions to write to repos.  I've installed a system called gitosis to handle the privileges through a special git repository. It uses Public Key cryptography rather than granting SSH accounts to everyone.  This makes it really easy to do your work securely without even needing a password.  For the curious, the actual mechanics of gitosis are detailed at [http://scie.nti.st/2007/11/14/hosting-git-repositories-the-easy-and-secure-way scie.nti.st]
+Repo visibility is completely customizable, as are individual permissions to write to repos.  I've installed a system called gitosis to handle the privileges through a special git repository. It uses Public Key cryptography rather than granting SSH accounts to everyone.  This makes it really easy to do your work securely without even needing a password.  For the curious, the actual mechanics of gitosis are detailed at [http://scie.nti.st/2007/11/14/hosting-git-repositories-the-easy-and-secure-way scie.nti.st]. Although that link may still work, there is also https://git-scm.com/book/en/v1/Git-on-the-Server-Gitosis.
 {{Messagebox |
@@ Line 33: / Line 30: @@
 git config --global diff.tool meld
 git config --global --add color.ui true
+# store password in memory for an hour
+git config --global credential.helper 'cache --timeout=3600'
 # recent packaged versions of git might be 1.8.3.1 (CentOS 7.4) whereas the current available is 2.15.1
 # push.default is unset; its implicit value is changing in
@@ Line 100: / Line 101: @@
 {{Highlight
 |text = If you want to browse the git help in your browser (as above), then make sure you <code>sudo apt-get install git-doc</code> to get the HTML files}}
+== Decentralized Workflow and Branching Model ==
+Here's a good explanation on how most groups use Git in a successful branching model for development, "master", release branches, hotfixes, etc.
+http://nvie.com/posts/a-successful-git-branching-model/
+== Submodules ==
+Using multiple repositories to compose your project.  See https://git-scm.com/book/en/v2/Git-Tools-Submodules
+<source lang="bash">
+git init myproject
+cd myproject
+git submodule add git@github.com:example.com/htdocs.git website
+git submodule add https://gerrit.wikimedia.org/r/p/mediawiki/core.git mediawiki
+git submodule add https://gitlab.com/Aranad/tools.git odtools
+cd mediawiki/
+git checkout REL1_31
+cd ../
+git commit -m 'initial commit'
+git diff --submodule
+git config --global diff.submodule log
+git diff
+git config -f .gitmodules submodule.mediawiki.branch REL1_31
+git submodule update --remote
+git status
+git commit -am 'tracking REL1_31 in the mediawiki submodule'
+git config status.submodulesummary 1
+git log -p --submodule
+cd mediawiki/
+git submodule update --remote --merge
+git config alias.sdiff '!'"git diff && git submodule foreach 'git diff'"
+git config alias.spush 'push --recurse-submodules=on-demand'
+git config alias.supdate 'submodule update --remote --merge'
+</source>
 == Tools ==
@@ Line 148: / Line 183: @@
 * http://flavio.castelli.name/2007/09/04/howto_use_git_with_svn/
-== Git Repo Hosting ==
-It seems everyone uses GitHub these days (~8 million users, 20 million projects).  It's not a bad solution, but there are some drawbacks, and whether you're just looking to host your own project or setup enterprise-wide git hosting, there are other ways to host your projects in Git.  Let's take a look at some options.
-<ol>
-<li>'''GitHub''' can make it a bit easier for developers who are used to working with svn because they have 'built-in' [https://github.com/blog/1178-collaborating-on-github-with-subversion svn client] support.<ref>Anyone can use <code>git svn</code> and all the other built-in git subversion bridging commands, GitHub simplifies how to do it.</ref>  GitHub [https://enterprise.github.com/home Enterprise] can be installed on your own servers.  GitHub costs money for private repos.
-<li>[https://about.gitlab.com/ '''GitLab'''] is the "popular" alternative to GitHub that comes in "Community", "Enterprise" and "Cloud" versions.  They say it's "[https://about.gitlab.com/better-than-github/ better than GitHub]"  One nice thing that I note is that they've integrated git-annex for large binary support.  This is a nice plus.  (I've personally used git-annex as a file backup system -- like DropBox. In my case, it was to make backups of UbuntuOne when that service was discontinued.)  You can install GitLab in minutes on your own server.  It's costs if you want the [https://about.gitlab.com/features/#compare Enterprise] version.<li>'''GitBlit''' is "a pure Java git server that just works".  It's a "true" open source project run by [https://www.linkedin.com/pub/james-moger/8b/3a3/65b James Moger] and scores of other contributors.  GitBlit is self-hosted, so you can get a feel for it quickly by looking at the projects own [https://dev.gitblit.com/ source code]. It does have some nice [http://gitblit.com/features.html features].
-The current Wikimedia Ops team is using [http://gitblit.com/ Gitblit] to drive https://git.wikimedia.org/ Gitblit is an open-source, pure Java stack for managing, viewing, and serving Git repositories.
-It's designed primarily as a tool for small workgroups who want to host centralized repositories.  It comes in two options: GO is an integrated single stack solution so you can really get up and running in no time flat; and there is a WAR version (assumes you already have a servlet container like Jetty or Tomcat.) Gitblit requires a Java 7 Runtime Environment (JRE)  Gitblit comes with a lot of [http://gitblit.com/features.html features]
-<li>[http://gitolite.com/gitolite/index.html gitolite] is similar to the now defunct '''gitosis'''.
-</ol>
 == Background ==
@@ Line 191: / Line 215: @@
 Only in /var/www/drupal/sites: www.example.org
 </pre>
+== Git Repo Hosting ==
+See [[Git repo hosting]]
 == Building a Git server ==