Git FAQ

Conflicts when performing core update

In the event you try to update you core and receive the error that you have a conflicts, the fastest resolution is often the -Xtheirs flag. This will attempt to automatically resolve the conflicts with a preference for upstream changes, and is safe to run if you don't have your own changes in any of the conflicting files (e.g. problems with .gitignore):

git pull -Xtheirs [upstream url] master

It's generally a good idea to double-check the conflicted files before going forward and make sure no bugs were introduced. The specific command you'll run depends on what version of Drupal you're running.

Drupal 7

Within your local environment run the commands:

git pull -Xtheirs git://github.com/pantheon-systems/drops-7.git master
# resolve conflicts here if needed...
git push origin master

Drupal 6

From inside your local git repository run the following commands:

git pull -Xtheirs git://github.com/pantheon-systems/drops-6.git master
# resolve conflicts here if needed...
git push origin master

What are the upstreams for Drupal Products

For users who need any of the upstreams for Drupal distributions on Pantheon in order to resolve a conflict we have added these URLs. If any of the upstream urls are not working or invalid, then please feel free to let us know and we can update the working list.

Open Academy: https://github.com/chapter-three/openacademy-drops-7.git
Open Atrium: https://github.com/phase2/openatrium-drops-6.git
Open Enterprise: https://github.com/levelten/openenterprise-drops-7.git
Open Outreach: https://github.com/nedjo/openoutreach-drops-7
Open Publish: https://github.com/phase2/openpublish-drops-7.git
Open Public: https://github.com/phase2/openpublic-drops-7.git
Panopoly: https://github.com/populist/panopoly-drops-7.git

Does Pantheon support git submodules?

We don't currently support git submodules, but we're evaluating whether it's the best approach to deliver to our users for managing upstream modules and themes.

Right now, the best approach is to just add and commit the code to git as normal files.

What are the git tags?

$: git tag
jenkins-ellis_update_drops_7-3
jenkins-ellis_update_drops_7-4
jenkins-ellis_update_drops_7-5
pantheon.import
pantheon_live_1
pantheon_live_2
pantheon_test_1
pantheon_test_2

The "update_drops" tags are from our upstream updates in the past (we don't tag them anymore, but used to).

The tag pantheon.import is your initial start state. pantheon_test_N and pantheon_live_N are created when you use workflow actions, so you can potentially revert to that state, produce diffs, etc.

Savvy git users may wonder, "if I create my own pantheon_test_N tag with a higher value N, can I push changes directly to test?" The answer is "yes, yes you can.".

How to revert or undo changes?

If you need to go back to a particular revision within the history of your project this can be done with a git reset in conjunction with a force-push.

However, it is _VERY_ important to note that by doing a reset and force-push will delete commits that were done after that revision. The lost of data will be permanent so be sure before you make this decision.

Start by getting the unique has for the commit that you want to revert to. You can find this by looking for the SHA hash from you site's dashboard.

git sha1 hash on Pantheon

Then use the git reset command, to revert to the desired commit. In this case, we'll roll back to bc9280.

git reset --hard bc9280
git push --force origin master

This will reset the Development environment back to that commit. You can then review the changes to make sure they are correct, and move forward with development as if the removed commits never happened.

How do I apply a patch from Drupal.org on Pantheon?

If you want to patch core or a module this is best done via git. You will need to switch from “on server development” if it's enabled.

Drupal.org has some very good instructions on applying patches with git .

From your local clone, you should be able to run the git apply command as per Drupal.org, commit your change and push back to Pantheon. A good best practice is to include a link to the issue/comment where the patch came from in your commit message.

Drupal.org also has instructions if you're looking to give back by creating patches for Drupal.

Importing with existing history

If you are importing a site that has an existing git history, you may be able to retain this history if you can successfully merge from the Pantheon upstream.

Start a new Pantheon site with a vanilla version of Drupal. Choose the version that's appropriate for your project.
Clone your vanilla Pantheon repository using the copy/paste string from the dashboard.

From within that clone, run something like:

		git pull -Xours [your existing repo] [existing site branch]

If there are conflicts, you'll need to resolve them. Note you'll get conflicts on all the binary files (e.g. favicion.ico) but you can just git add them again.
Ideally there will be no other conflicts. Once this is done, you can push back to Patheon:
```
		git push origin master
```
On the Pantheon dashboard's git log, we only show the first-parents. This means we will only show the commit you directly push to your Pantheon site because otherwise users would have their changes swamped by Drupal commits after every upgrade. You can run git log from within your repository to view your full history.

Can I use git with On Server Development?

Not simultaneously. It's an either/or decision.

When you switch to On Server Development you will not have the ability to interact with your code via git. If you try pushing, it will be blocked.

It is also worth noting that if you have On Server Development disabled then you can interact with your code vit git.

What version of git do you run?

We are currently running git 1.7

Debugging Errors

Pushes denied because of changes in sites/default/files

If you find that you are running into issues with commits that reference sites/default/files, you can use the filter-branch command to rewrite those references out of your repository. The technique has been documented by the engineers at github.

From within the Drupal root of your site:

git filter-branch -f --index-filter 'git rm -rf --cached --ignore-unmatch \
sites/default/files' --prune-empty -- f4160148..HEAD

The commit f4160148 is one from pretty far back in the Drupal 7 history, guaranteed to pre-date the start of the specific site project. Using the range between that and HEAD prevents filtering the entire Drupal project history, which can take a while. If you're on Drupal 6 you'll need to find your own starting point by looking at the git log. You might also pick a more recent starting point for Drupal 7 if you're in a hurry.

Pushes denied because remote upstream URL has changed

We are updating our infrastructure so that code repositories do not have a single point of failure. To do this we are moving to a more distributed code server binding model.

How and Why we are making this chage:

As a result the git connection string format will change to support this change. This will start as a feature flag that you can optionally enable on a per-site basis, so you can opt-in to evaluate the settings.

If you have created a local clone of your site, then you will need to update the default remote origin with the new format for connection strings. Before you can push updates you must update your remote url. To do so run:

git remote set-url origin ssh://codeserver.dev.{site}@codeserver.dev.{site}.drush.in:2222/~/repository.git

By default your remote will be named origin. If you have renamed your Pantheon site's upstream to something else you will have to change origin in the command above.

Can't connect to git

If you are having a problem cloning your git repository, the problem may be that you have not enabled your ssh key in your account's dashboard. There is a wiki page to help you get started and adding the SSH key to your Pantheon account.

I added the public key but I get prompt for my password

This can occur if you have multiple SSH keys. More information about how to debug that problem can be found in this article about resolving Public key authentication issues with git.

The easiest way to find out which SSH keys your git client is using when trying to connect is running the following command:

ssh -vT git@code.getpantheon.com

The output should be similar to this:

debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to code.getpantheon.com [50.57.148.117] port 22.
debug1: Connection established.
debug1: identity file /home/username/.ssh/id_rsa type 1

From here you should be able to configure git with the matching ssh key and clone your repository.

Manually Resolving Conflicts

Conflicts can occur when the upstream you are trying to merge your code with has made alterations to files.

"When a merge isn’t resolved automatically, git leaves the index and the working tree in a special state that gives you all the information you need to help resolve the merge." - Git Manual

Delete Merge Conflicts

To manually delete merge conflicts from the terminal, use the following commands in sequence:

Start by identifying the file that is generating a delete error.

For example, the git log may contain an entry similar to the following:
```
CONFLICT (delete/modify): scripts/run-tests.sh deleted in HEAD and modified in 72faeeff1c9356221694d1351cdb2000ab3c5d1c. Version 72faeeff1c9356221694d1351cdb2000ab3c5d1c of scripts/run-tests.sh left in tree."
```
From your local repository, you can run the following git command, which will get you a copy of the file in conflict:
```
git checkout <commit ID> -- <file>
```
When looking for a commit ID, you can find the last instance where the missing file was in the repository.

Run git status and verify that their is a new file to add to the repository:

git status
# On branch master
# Changes to be committed:
# (use "git reset HEAD ..." to unstage)
#
#	new file: README.txt
#

Next, you will need to run:
```
git add .
```
After performing the add, commit the file with an accompanying commit message.
```
git commit -am "verifying missing README.txt"
```
You will receive confirmation from git that the file has been committed.
Lastly, you will need to run:
```
git push origin master
```

Fast forward errors when you try to push

If you are getting errors with the committing of you reverted changes then you should make sure that you have included the -f option as you will be forcing a fast-forward update. Without this you will receive an error similar to the one below.

$: git push 
To git@code.getpantheon.com:3ef6264e-51d9-43b9-a60b-6cc22c3081c9
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'git@code.getpantheon.com:3ef6264e-51d9-43b9-a60b-6cc22c3081c9'
To prevent you from losing history, non-fast-forward updates were rejected
Merge the remote changes (e.g. 'git pull') before pushing again.  See the
'Note about fast-forwards' section of 'git push --help' for details.

I have a git conflict; can you fix it for me?

No. Git is a powerful and useful tool, but it does take some time working with it hands-on to effectively use it. We do provide a number of resources and documentation to address various issues such as, importing a site and keeping the git history, git issues performing core updates, and resetting your code to a specific commit.

There are number of patterns and strategies of git code management for single users to large teams and each has its own merits, drawbacks and nuances.

As a result of the range of varying techniques and to prevent code from being accidentally over-written, it is up to the developer to address these when they occur as git conflict resolution is a critical and important part of your workflow.

How can I delete a remote branch?

git push origin :branchname

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