Developing with Git
As of January 1, 2010, OpenNMS is now using git as its primary source code management tool.
More information on git: http://git-scm.com
- 1 Viewing the source
- 2 Install the Git source code management tool
- 3 Fork or clone the OpenNMS repository
- 4 Initial Git configuration
- 5 About the OpenNMS Git Repository Branches
- 6 Creating a Branch and Making Changes
- 7 Pushing Changes Upstream
- 8 Other useful git operations
- 9 Git Resources
Viewing the source
To just view the current source, git is not needed. You can browse our Git repository directly 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
Fork or clone the OpenNMS repository
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, clone out *your fork* of the code, not the OpenNMS official repository.
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
Now add the official OpenNMS as your upstream repository so git knows where to merge new changes from done by others.
git remote add upstream https://github.com/OpenNMS/opennms.git
Now confirm your private fork has the alias "origin" and the official repository as having the alias "upstream".
$ git remote -v origin https://github.com/my-github-username/opennms.git (fetch) origin https://github.com/my-github-username/opennms.git (push) upstream https://github.com/OpenNMS/opennms.git (fetch) upstream https://github.com/OpenNMS/opennms.git (push)
After this, the overall process is to make changes locally and then commit any desired changes to your 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.
This process is described in more detail below.
Option 2: Getting OpenNMS by cloning the official 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, or for people who already have read/write access to the official repository.
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 firstname.lastname@example.org: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.
Initial Git configuration
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 "email@example.com"
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 "firstname.lastname@example.org"
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
About the OpenNMS Git Repository Branches
There are 2 primary branches in the OpenNMS git repository, representing different stages in development.
- The develop branch is for general development of new features that will be going into the next major version of OpenNMS. This is the normal target branch for patch submissions.
- (release-xx.x.x branch)
- This is released code branch for the specified version of OpenNMS 12
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).
Creating a Branch and Making Changes
At this point, you have a locally cloned copy of your private fork of the OpenNMS repository, as described above. Change to the "src/opennms" folder.
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 ...
To view just your local branches, leave the
-a flag off. The "master" branch is the default initial branch
$ git branch * master
Checkout 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_local_branch_name) [source_branch_name]
In most cases, it is recommended that you branch from the main "develop" branch of the upstream OpenNMS GitHub repository.
$ git checkout -b feature-new-awesome-thing remotes/upstream/develop Branch feature-new-awesome-thing set up to track remote branch develop from upstream. Switched to a new branch 'feature-new-awesome-thing'
This created a local branch called "feature-new-awesome-thing" based on the official OpenNMS repository remote branch "remotes/upstream/develop".
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 * feature-new-awesome-thing master
Create your changes as normal, editing/adding/removing files, and committing them to the local repository with "git commit".
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, one local file has been changed compared to the repository.
$ git status # On branch feature-new-awesome-thing # 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: README.md # 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 to your online repository.
View Your Changes
This displays each recent commit in commit order. Each commit will have a unique commit identifier, the author and the time of the commit. Note that this displays the entire commit history of the current branch, yours and others.
$ git log
After committing changes, "git status" will show your local branch as ahead of the upstream repository.
$ git status # On branch ... # Your branch is ahead of 'upstream/develop' by 9 commits. # nothing to commit (working directory clean)
Make Your Branch Public
When you are ready for your code to be accessible by other people, you can push your feature branch back to your online GitHub repository like so:
$ git push --verbose origin feature-new-awesome-thing Pushing to https://github.com/your-name/opennms.git POST git-receive-pack (chunked) To https://github.com/your-name/opennms.git * [new branch] 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 your online GitHub repository where now other people can check it out as well.
Pushing Changes Upstream
First of all, if you're going to submit patches, please fill out the OpenNMS Contributor Agreement.
Option 1: No Commit Access, using a GitHub pull request
Submitting a GitHub pull request is now the preferred method for submitting patches to OpenNMS.
This page describes the general process: https://help.github.com/articles/using-pull-requests
By this point, you have pushed your new branch to your online fork of the OpenNMS repository.
Go to your GitHub patch and ensure your new branch is selected in the branch drop-down. You should see your branch is n commits ahead of "OpenNMS:develop".
Click the green "Compare & review" button to the left of your branch name. Review your
When you're ready to submit your pull request, click "Create pull request".
On the next screen, give a descriptive title to your pull request, including the OpenNMS JIRA issue tracker NMS-xxxx ticket number related to your change. The pull request can also be described in the comment block. Click "Create pull request" on the right to finish submitting the pull request.
Your pull request will be assigned a number and go into queue for review. Add the pull request URL to the JIRA ticket associated with it in JIRA so there is a record in the ticket that a pull request exists to address it.
Option 2: No Commit Access, using a patch submission
This method prepares a text patch for posting in the bug tracker web site or for submitting by e-mail.
git format-patch -M -C (upstream-branch)
to generate a set of commit patch files between the upstream branch and your current branch. (Note: The -M flag is necessary to track file renames):
$ git format-patch -M -C remotes/upstream/develop 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 <email@example.com> 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 + -- 126.96.36.199
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.
Option 3: 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
Other useful git operations
To get the latest updates from your repository on GitHub to in your local system, 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
First, fetch changes:
$ git fetch upstream
Switch to your local "develop" branch
$ git checkout develop
And merge changes from the upstream develop branch to your local "develop" branch:
$ git merge upstream/develop
Then, optionally, push the changes on your PC up to your GitHub online private repository.
$ git push origin develop
Cleaning up after switching branches
Switching between two branches that are based on very different remote branches (e.g. 1.12.3 and develop) 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
Deleting your branch
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-thing Deleted 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 firstname.lastname@example.org:OpenNMS/opennms.git - [deleted] feature-new-awesome-thing
Applying a patch made on one branch to another branch
If you originally made a patch against one branch and would like to apply the same patch to another branch, the "git cherry-pick" command can do this.
Use "git log" to identify the patch commit hash value and then checkout the desired branch and re-apply the patch.
git checkout (new-branch-name, e.g. develop) git cherry-pick (patch hash)
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.