This document describes the process of cloning the central OpenLayers repository and making changes to it. It is really only relevant to developers who are currently core committers to the OpenLayers subversion repository. If you are interested in contributing to the future of OpenLayers, please clone the central repository, make changes, and issue pull requests. We welcome your contributions and appreciate the help!
This document doesn't cover the git basics. The help pages on GitHub are a good place to start learning git.
There two type of changes developers will be making to the central OpenLayers repository. The first type will be commits that add features toward the OpenLayers v3 API or remove parts of the v2 API. The second type of change will be merges that come from the remote OpenLayers subversion repository.
To make changes to the central git repository, you can fork it, add a reference (perhaps named "central" or "upstream") to the central repository, and push commits directly from your working copy. In addition, you can clone the central repository and push commits back to the "origin." The second process is described below.
First, clone the central repo:
git clone [email protected]:openlayers/openlayers.git ol3
Now you can make changes, commit often, and push commits:
cd ol3
hack hack hack
git commit -m "Making things awesome."
hack hack hack
git commit -m "Making things awesomer."
git push origin master
This section describes how to fetch changes from the OpenLayers subversion repository, merge those into the master git branch, and push them to the central repository on GitHub. The purpose for doing this is to bring changes from the 2.x line of development into the 3.x line of development. Not everybody will have to do this. And it should be done with caution. As the version 3 API changes from the v2 API, there will be increasing conflicts in the merges.
First, check out (and change into) the 2.x branch if you haven't already. From within your ol3 git repository, run the following:
git checkout -b 2.x origin/2.x
The next thing you need to do to be able to merge in changes from subversion is to configure your working copy of the central git repository to know about the remote svn.
git svn init http://svn.openlayers.org/trunk/openlayers
git config svn.authorsfile authors.txt
Note: The authors file links authors in subversion commits to GitHub users. The user names and emails in the authors file correspond to GitHub usernames and emails. Don't change this file unless you are correcting a GitHub user's information or adding a new author from the subversion log.
Finally, you need to configure your repo so it knows about the latest commit that the remote git-svn refers to. To do this, run the following:
git show origin/2.x | head -n 1 | sed 's/commit //' > .git/refs/remotes/git-svn
At this point, your local git repository should be configured to fetch changes from the remote OpenLayers subversion repository. Changes from this repository could be fetched (and applied to) any branch in your git repository, but by convention, we'll only apply changes from the SVN repository to the 2.x branch. Commits to the 2.x branch (which should only come from SVN) can be merged to your master branch (or any other) and then pushed to the central repository.
To confirm that your repository is correctly configured, run the following:
git svn info
You should see something like what you'd expect from svn info inside a
working copy of a subversion repository. The first time you run it, you'll get
a lot of extra output about rebuilding the revision map.
As mentioned above, you can fetch changes into any of your git branches, but by convention, we only apply changes from the subversion repository to the 2.x branch.
If you haven't already, change into your 2.x branch (always run git branch
before fetching or making changes to confirm what branch you are on) and pull
the latest changes:
git checkout 2.x
git pull origin 2.x
We expect all the changes in this branch to come from subversion - so you should
never make commits (with git commit) directly to this branch. Instead, we
always fetch changes from the remote subversion repository. Run the following
to fetch changes and apply them as commits to your 2.x branch.
git svn rebase
At this point, you can push the commits from your local 2.x branch (the changes that came from svn) to the central git repo:
git push origin 2.x
As with any other branch, changes from the 2.x branch can be merged into your master branch. As the OpenLayers v3 API diverges from the v2 API, these merges will likely come with a number of conflicts. Resolve these conflicts with care.
To merge changes (without conflict resolution), change to your master branch, pull the latest from the central repository, and merge changes from your 2.x branch.
git checkout master
git pull origin master
git merge 2.x
If all goes well, you can push the merged commits to the central repository:
git push origin master
If GitHub burns down and everybody with a clone quits their job and goes surfing, the git repository can be recreated with something like the following steps (the second one takes a long time to run, so I'm not going to reproduce it to confirm):
First, create an authors.txt file from an updated working copy of the svn repo:
#!/usr/bin/env bash
authors=$(svn log -q | grep -e '^r' | awk 'BEGIN { FS = "|" } ; { print $2 }' | sort | uniq)
for author in ${authors}; do
echo "${author} = NAME <USER@DOMAIN>";
done
Run this and save the output as authors.txt. Credits to Josh Nichols for the script. Edit this authors file to correct any GitHub user names or email addresses.
Next, run the following (and substitute the path to the above mentioned authors.txt):
git svn clone -A path/to/authors.txt http://svn.layers.org/trunk/openlayers ol3
cd ol3
git remote add origin [email protected]:openlayers/openlayers.git
git checkout -b 2.x git-svn
git push -all origin
cp path/to/authors.txt .
git commit -am "Adding authors file."
git push origin 2.x
git checkout master
git merge 2.x
git push origin master