## Apache Tamaya — Development Guide

### Suggested Git Workflows

#### Avoid git pull!

`git pull` should never get invoked if you have dirty files lying around or if your branch is ahead of master. This will always lead to some dirty artifacts in the commit history:

    Merge branch 'master' of http://git-wip-us.apache.org/tamaya into master

#### Use git pull --rebase

An easy version for getting rid of the auto-merges is using

    $ git pull --rebase

Please note that this sometimes trashes your working tree if there are unmergeable files around. Cleaning this up with a forced manual rebase is not something we would recommend for a git beginner.

#### Working in an own branch

This is actually the suggested way to prevent auto-merges. Create an own branch where you do your feature work. Either do all your work in one branch or create one branch per feature you are working on.

    $ git branch mybranch

After you finished your feature, first add (`git add`) and commit (`git commit`) your work. Check with `git status` that you don’t have any dirty files and uncommitted changes around. You can use `git stash` to 'backup' unfinished work.

Then switch back to the master branch and pull changes done by other committers in the meantime.

    $ git checkout master
    $ git pull --rebase

You should now get all the changes done by other committers and the will get applied to your local master branch. Now go back to your private branch and rebase your locally performed work to the HEAD of master.

    $ git checkout mybranch
    $ git rebase master

If you got conflicts, you will get lines with ">>>>" added to those files. Resolve those conflicts manually, add them and finish the rebase.

Check with `git-status` and `gitk` if the merge went well and the history now contains your changes. If all is well, go back to the master branch and merge your changes in.

    $ git pull --rebase     // (just for safety, you should see no changes)
    $ git checkout master
    $ git merge mybranch

Finally you can push your changes to the ASF git repo

    $ git push

### Contribution workflow

#### Creating patches

You should use the following workflow, if you plan to contribute patches or new features to Tamaya.

First update you local copy of the repository:

    $ git checkout master
    $ git pull --rebase

Then create a new local branch for your work. It’s good practice to name it after the corresponding JIRA issue.

    $ git checkout -b TAMAYA-XXX

Now you can start to work on your patch. When you are finished, commit your changes. But don’t forget to add the name of the JIRA issue to the commit message.

    $ git add -am "TAMAYA-XXX: Fixed some issue"

For small patches we recommend to do a single commit containing your changes. For larger contributions you should try to group your work into separate sub-tasks that you can commit one by one.

Before you create your patch you should make sure that your local repository is up to date with the master repository. This is very important especially if you work on your branch for a long time. Use the following commands to pull the latest changes from the upstream repository and rebase your branch against the current master.

    $ git checkout master
    $ git pull --rebase
    $ git checkout TAMAYA-XXX
    $ git rebase master

Now you are ready to create your patch:

    $ git checkout TAMAYA-XXX
    $ git format-patch --stdout master > ../TAMAYA-XXX.patch

Please attach the resulting patch file to the correspoding JIRA issue.

#### Applying patches

If you are a committer and want to apply a patch you should do so in a separate branch.

    $ git checkout -b TAMAYA-XXX

Then apply the patch using `git am` and rebase it against the master branch.

    $ git am < ../TAMAYA-XXX.patch
    $ git rebase master

After reviewing the changes and testing the code, the changes are ready to be merged into the master branch:

    $ git checkout master
    $ git merge TAMAYA-XXX
    $ git branch -d TAMAYA-XXX

#### Discussion workflow (optional)

All discussions which lead to a decision take place on the mailing list. Sometimes it’s required to show-case an idea esp. if the solution is more than few lines. As shown above it makes sense to use local branches for developing new parts. Git allows to push such local branches to a public repository. So it’s easier to share it with the community for discussing it. The following listings show an example in combination with GitHub - for sure it works with any hosting platform like BitBucket, Google-Code,…​ The only important part here is that such branches NEVER get pushed to the main Apache repository to keep the commit history as clean as possible.

#### Initial setup

    $ git clone https://git-wip-us.apache.org/repos/asf/incubator-tamaya.git
    $ git remote add discuss https://[username]@github.com/[username]/[repo-name].git
    $ git push -u discuss master

#### Branches for discussions

    $ git checkout -b TAMAYA-XXX # 1-n commits
    $ git push discuss TAMAYA-XXX # share the link to the branch for the discussions

If the community agrees on the suggested change, the implementation will be applied to the origin master. A committer has to follow the steps described above for the basic workflow to keep the commit history simple, clean and straight. A contributor has to follow the steps described above for creating a patch.

#### Delete the branch again

    $ git push discuss :TAMAYA-XXX
    $ git branch -d TAMAYA-XXX