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Once the code is cleaned up and we have less repositories we will move the code to the slac-lcls organization. This organization will also be used by the DAQ group and allows to group all of your code development together.

GitHub account

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Content

Setup git

The following steps describe how to setup git. This setup has to done only once for the machine where you are planing to develop code.

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git config --global user.name "my name"<my-name>

Setting the email address in git:

git config --global user.email "my email"<my@email>

Confirm that your user name is correct by:

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Check if you already have an ssh key by checking if the following file exists: ~/.ssh/id_rsa.pub and not empty.

If yes, create a new ssh key on GitHub and copy the content of ~/.ssh/id_rsa.pub to the Key section.

If you don't already have a ssh key, create a new one with the following command

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

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<my@email>"

Then on prompt enter the name of ssh key file, e.g. ~/.ssh/id_rsa.

Newly created ssh key file should be added to the ssh-agent by commands

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_rsa

Afterwards add a new ssh key on GitHub and copy the content of ~/.ssh/id_rsa.pub

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to the Key section.

Accessing GitHub from psdev (and other internal networks)

To access GitHub from psdev/psana and other internal networks that lack a direct connection to the Internet, please use psproxy as the ssh/HTTPS proxy. 

For SSH access, please edit/create the file ~/.ssh/config and add the following; replacing <your_unix_id> with your unix account id.

Host code.stanford.edu
  Hostname code.stanford.edu
  User git
  ProxyCommand ssh <your_unix_id>@psproxy nc %h %p

Host github.com
   Hostname github.com
   User git
   ProxyCommand ssh <your_unix_id>@psproxy nc %h %p

NOTE: make sure you "chmod 600 ~/.ssh/config", otherwise ssh will complain, bitterly.

To access GitHub repos using HTTPS, set your Git http.proxy using 

git config --global http.proxy http://psproxy:3128

Useful Commands

Check status of the repo

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git clone git@github.com:lcls-psana/<some -repository>.git

The repository where you clone from is typically called "upstream".  This is the global copy of the repository that all developers share and work on together.

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git commit -a -m "commit message"

 Push Push commits upstream

After committing the changes into the local repository they have to be pushed upstream to make them available for the other developers.

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This can fail if upstream is ahead of you local version. In this case you first have to get the most recent changes from upstream:

Here is a blog post that explains the difference between merge and rebase

git fetch origin 
git rebase -p origin

Resolving Conflicts

If the local commits and the commits from upstream will modify the same line in the same file, this will result in a merge conflict .

This conflict can be resolved in two different ways:

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The conflict can be resolved by ignoring the local changes and using the version of the file from upstream

git rebase --skip

This will overwrite your local changes with the upstream changes.

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reported by the above rebase command.

It is simplest to resolve the conflict manually. The command "git diff" will show the lines that were changed locally and by the upstream version. This file can now be added to keep whatever part of the local or remote change you want.

After the merge conflict is resolved commit your changes

git commit -a -m "commit message"

And then continue with the rebase and push everything upstream

git rebase --continue
git push origin master

Tag new release

To create a new release from the current version of the local repository and push it upstream do:

git tag -a V00-00-01 -m "Version V00-00-01"
git push origin V00-00-01

Create new repository

New repositories can be created directly on GitHub in the organization

https://github.com/lcls-psana (green New button on the right)

Afterwards just clone the new repository and the follow the workflow above

Convert svn repository to git

The python 3 code to convert repositories from svn to git is at:

https://github.com/lcls-psana/psdm-svn2git

The script can be run like this to convert a svn repository to git:

python svn2git.py -u https://pswww.slac.stanford.edu/svn-readonly/psdmrepo/xtcav 

References

• Conda Release System
• SSH keys