Developing with Git
As of January 1, 2010, OpenNMS is now using Git as its primary SCM.
- 1 Browsing Git
- 2 Install the Git source code management tool
- 3 Option 1: Getting OpenNMS by forking the GitHub repository
- 4 Option 2: Getting OpenNMS by cloning the GitHub repository
- 5 Getting Started with Git
- 6 Configuring Git
- 7 Working with Branches
- 8 Recommended Workflow
- 9 Resources
You can browse our Git repository at GitHub.
Install the Git source code management tool
Install Git as appropriate for your platform.
On Debian/Ubuntu systems, the following command will install Git.
sudo apt-get install git
Option 1: Getting OpenNMS by forking the GitHub repository
As of 2014, the preferred method for OpenNMS developers to receive code contributions is for you (a potential contributor) to create a GitHub site account and then fork the GitHub repository into a private repository instead of cloning the main opennms repository directly.
Forking the opennms repository creates a private copy of OpenNMS that you can change and commit to that is tied to your github account.
This article describes the overall process: https://help.github.com/articles/fork-a-repo
To create a private fork, go to https://github.com/OpenNMS/opennms and then click the "Fork" button in the upper right. This will create a private fork of the codebase.
Then, check out *your fork* of the code. So instead of checking out:
you would check out:
$ mkdir src $ cd src $ git clone https://github.com/my-github-username/opennms.git ... (a directory "opennms" will be created below the current directory) $ cd opennms
Make changes locally and then commit any desired changes to that fork using 'git commit' (where you will have commit access since it's your private fork or copy of the code) and use the instructions in the article below to notify us of the changes as a 'pull request'.
Then we can review them on github and merge them into the OpenNMS/opennms.git repository.
The general pull request procedure: https://help.github.com/articles/using-pull-requests
Option 2: Getting OpenNMS by cloning the GitHub repository
This is the option for people who just want a local copy of the source code without the intention make changes or to submit them back.
First, you must clone the OpenNMS Git repository.
This command is the usual one for people without read-write access to the repository:
$ git clone git://github.com/OpenNMS/opennms.git ... (a directory "opennms" will be created below the current directory) $ cd opennms
If you have commit access to the OpenNMS repository, you can clone it read-write instead:
$ git clone email@example.com:OpenNMS/opennms.git ... (a directory "opennms" will be created below the current directory) $ cd opennms
Unlike Subversion, when you clone a git repository, you have all of the commit history back to the creation of the codebase, as well as access to any branches and tags defined in the remote repository. That means that it is possible to do development on multiple portions of the OpenNMS codebase without needing network access. You can commit changes locally as necessary, without having to go back and forth to the upstream server.
Getting Started with Git
There are some things you should do to configure Git for your repository before you go any further. Ensure you are in the "opennms" top-level source code directory.
First, configure it to know who you are:
$ git config user.name "FirstName LastName" $ git config user.email "firstname.lastname@example.org"
Or, if you have many git repositories under your current user, you can set this for all of them
$ git config --global user.name "FirstName LastName" $ git config --global user.email "email@example.com"
If you want pretty colors, you can setup the following for branch, status, and diff commands:
$ git config --global color.branch "auto" $ git config --global color.status "auto" $ git config --global color.diff "auto"
Next, if you are comfortable with the way Subversion works, you will probably want to configure Git to push changes to the same location they are branched from:
$ git config push.default tracking
Working with Branches
The OpenNMS Git Repository Branches
There are 2 primary branches in the OpenNMS git repository, representing different stages in development.
- The 1.12 branch is for doing small bugfixes or features suitable for inclusion in a future stable release.
- The master branch is for general development of new features that will be going into the next major version of OpenNMS.
In your local git repository, these are accessible as "remote" branches, i.e., branches that reference a location on a remote repository (in this case, the OpenNMS git repository).
For a full list of branches in your cloned repository, use
git branch -a:
$ git branch -a * master remotes/origin/1.10 remotes/origin/1.10-GpMonitor remotes/origin/1.12 ... remotes/origin/HEAD -> origin/master ...
To view just your local branches, leave the
-a flag off. The "master" branch is the default initial branch
$ git branch * master
Working on a Branch
If you are used to Subversion, you will notice that branches work a bit differently in Git. Remote branches are not directly accessible, since they represent the state of a branch in another Git repository. If you attempt to check one out directly, you will get a warning:
$ git checkout remotes/origin/1.10 Note: moving to 'remotes/origin/1.10' which isn't a local branch If you want to create a new branch from this checkout, you may do so (now or later) by using -b with the checkout command again. Example: git checkout -b <new_branch_name> HEAD is now at 2047359... make sure that if pkg is null we return false
Instead, what you want to do is create a local branch from the remote one, using the syntax, "
git checkout -b <new_branch_name> [source_branch_name]":
$ git checkout -b 1.12 remotes/origin/1.12
This created a local branch called "1.12" based on the remote branch "remotes/origin/1.12".
Note that it says it is set up to track the remote branch. That means that Git knows that your branch was created from the remote branch, and will automatically know what to do if you wish to push changes to that branch.
Now when you do a "git branch" it will show that your active branch is the one you created:
$ git branch * 1.12.3 master
Cleaning up after switching branches
Switching between two branches that are based on very different remote branches (e.g. 1.12.3 and master) may leave stuff from the switched-from branch in your filesystem that is not present in the switched-to branch. The following commands are useful for correcting this problem; note that running them causes all uncommitted changes in your current branch to be lost:
$ git reset --hard HEAD $ git clean -f -d -x
To get the latest updates from the github hosted remote origin in your private tree, run "
$ git pull Already up-to-date.
This will retrieve any changes that have been made and apply them to your repository.
However, the larger source of changes will be in the OpenNMS upstream repository. To stay current, sync your local private repository to the OpenNMS upstream public repository.
This page describes the process in more detail: https://help.github.com/articles/syncing-a-fork
In summary, first define the OpenNMS repository as the upstream repository:
git remote add upstream https://github.com/OpenNMS/opennms.git
and then fetch changes:
git fetch upstream
To push the changes on your PC up to your github online private repository, do a
git push origin
To see what remote repositories are registered, run
git remote -v
Git is slightly different from SVN in that by default, no changes you make to files will be committed unless you specifically "git add" them. Otherwise, you will get something like this from "
In the following example, two local files have been changed compared to the upstream repository.
$ git status # On branch 1.12.3 # Changes not staged for commit: # (use "git add <file>..." to update what will be committed) # (use "git checkout -- <file>..." to discard changes in working directory) # # modified: debian/changelog # modified: debian/control # no changes added to commit (use "git add" and/or "git commit -a")
If you are only modifying files, you can just run
git commit -a
when it's time to commit your changes, and it will automatically "git add" any modified files. Note that this does not add any new files or directories that have been created, however.
Also note, this is only committing files to your local repository. Once you have your local branch to your liking, it's time to push the changes back upstream.
After committing changes, "git status" will show your local commit status as 1 commit ahead of the upstream repository.
$ git status # On branch 1.12.3 # Your branch is ahead of 'origin/rc/stable/1.12.3' by 1 commit. # nothing to commit (working directory clean)
Pushing Changes Upstream
First of all, if you're going to submit patches, please fill out the OpenNMS Contributor Agreement.
No Commit Access
If you do not have commit access, you can still easily submit patches to the project, thanks to Git's easy formatting of changes.
git format-patch -M -C <source-branch>
to generate a set of commit patch files between the source branch and your current branch. (Note: The -M flag is necessary to track file renames):
$ git format-patch -M -C remotes/origin/1.10 0001-testing-commits.patch 0002-removing-that-line-again.patch
Each commit gets a file which contains the patch, as well as some metadata (in the form of a standard email) that makes it easy to import into someone's git repository.
$ cat 0001-testing-commits.patch From 26ed1d96e18db80ff76d0f462bb4b33b648e94e5 Mon Sep 17 00:00:00 2001 From: Benjamin Reed <firstname.lastname@example.org> Date: Tue, 22 Dec 2009 15:41:05 -0500 Subject: [PATCH 1/2] testing commits --- README.build | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/README.build b/README.build index b82d49b..cc57eb8 100644 --- a/README.build +++ b/README.build @@ -1 +1,2 @@ See the instructions at http://www.opennms.org/index.php/Building_OpenNMS + -- 22.214.171.124
Just open a bug in JIRA as an enhancement, and attach your patches.
If you want to get fancy, see this page for details on how to "rewrite history" so you can have one patch per feature.
No Commit Access, using a git pull-request
This page describes the process: https://help.github.com/articles/using-pull-requests
With Commit Access
If you have commit access, all you need to do is run "
git push" from your branch. If you have configured "push.default" as above, you don't need to give it any arguments:
$ git push
Branch from Stable or Unstable
If you are working on a new feature, it is recommended that you branch from the appropriate version (1.10 - stable, or master - unstable) depending on the scope of your feature.
$ git checkout -b feature-new-awesome-thing remotes/origin/master Branch feature-new-awesome-thing set up to track remote branch master from origin. Switched to a new branch 'feature-new-awesome-thing'
Create your changes as normal, editing/adding/removing files, and committing them to the local repository with "git commit".
You can update your branch with the latest changes by doing a "git pull":
$ git pull Already up-to-date.
Make Your Branch Public
When you are ready for your code to be accessible by other people, you can push your feature branch like so:
$ git push [--verbose] origin feature-new-awesome-thing Pushing to email@example.com:OpenNMS/opennms.git Counting objects: 5, done. Delta compression using up to 2 threads. Compressing objects: 100% (3/3), done. Writing objects: 100% (3/3), 283 bytes, done. Total 3 (delta 2), reused 0 (delta 0) To firstname.lastname@example.org:OpenNMS/opennms.git 2047359..732c8a5 feature-new-awesome-thing -> feature-new-awesome-thing updating local tracking ref 'refs/remotes/origin/feature-new-awesome-thing'
This will create a "feature-new-awesome-thing" branch in remotes/origin/ based on your changes, and now other people can check it out as well, after a "git pull".
In the case of this example, our branch, "feature-new-awesome-thing" is tracking master. However, if you've pushed your branch to the upstream so you can collaborate with other people, it's possible they've made changes as well. You can merge any changes made to the remote branch by using "git pull" with arguments:
$ git pull origin feature-new-awesome-thing From email@example.com:OpenNMS/opennms.git * branch feature-new-awesome-thing -> FETCH_HEAD Already up-to-date.
Merging the Code Upstream
When it's time for the code in the branch to be merged, check out the appropriate branch (creating it locally if it doesn't exist already) and pull the changes from your branch.
It is important to always use --squash on your commits so they can be easily cherry-picked to another branch if necessary.
# make sure everything's up-to-date
git checkout master# this will take all of your commits on your branch and turn them into 1 commit on your master
git merge --squash feature-new-awesome-thing
...then push them to the upstream repository:
git push originTotal 0 (delta 0), reused 0 (delta 0) To firstname.lastname@example.org:OpenNMS/opennms.git 2047359..732c8a5 master -> master
If you're done with the feature branch, you can delete it.
To delete the local branch, use "
git branch -D":
git branch -D feature-new-awesome-thingDeleted branch feature-new-awesome-thing (was 732c8a5).
To delete the remote branch, the syntax is a little funky, since it's just like pushing a branch: "
git push origin <local-branch>:<remote-branch>". In this case, you push nothing (an empty string) as the local branch:
$ git push origin :feature-new-awesome-thing To email@example.com:OpenNMS/opennms.git - [deleted] feature-new-awesome-thing
There are a lot of other resources for help with git:
- Git Quick Start Guide
- Git Cheat Sheet
- Git Remote Branch tool (useful for tracking/publishing remote branches, requires RubyGems)
Additionally, every single git command has pretty extensive documentation. Just run "git help <command>" for help with a given command.
usage: git [--version] [--exec-path[=GIT_EXEC_PATH]] [--html-path] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS] The most commonly used git commands are: add Add file contents to the index bisect Find by binary search the change that introduced a bug branch List, create, or delete branches checkout Checkout a branch or paths to the working tree clone Clone a repository into a new directory commit Record changes to the repository diff Show changes between commits, commit and working tree, etc fetch Download objects and refs from another repository grep Print lines matching a pattern init Create an empty git repository or reinitialize an existing one log Show commit logs merge Join two or more development histories together mv Move or rename a file, a directory, or a symlink pull Fetch from and merge with another repository or a local branch push Update remote refs along with associated objects rebase Forward-port local commits to the updated upstream head reset Reset current HEAD to the specified state rm Remove files from the working tree and from the index show Show various types of objects status Show the working tree status tag Create, list, delete or verify a tag object signed with GPG See 'git help COMMAND' for more information on a specific command.