databricks, github, version control

Multi-user Branching Approach using Databricks

In my previous post on version control using Databricks, we looked at how to link GitHub and Databricks. Following on from this I wanted to show a simple branching methodology that could work for a small team collaborating in the Databricks environment. This is for an environment where the users will not pull code down onto their own machine and are potentially new to git in general.

This is not a CI/CD pipeline and isn’t a large scale solution. It’s also very manual and I would recommend looking at something like devops pipelines or even GitHub actions (which I will discuss another time).

In this example, we will have two main branches; master and development. This is pretty standard practise. We are assuming that developers clone from and make pull requests to development and then admins sync up development and master. I won’t be discussing branch policies or anything like that but feel free to ask if you have any questions about how to set those up.

For every feature a new branch will be created by the developer. This is called feature branching.

You will need to read the previous post as we will start where we left off; with our master code folder.

Create a Development Branch

Now we are also going to add a branch for development code in Databricks. To do this, clone a copy of the master file to a development folder in Databricks. Ensure the filename is kept the same for consistency.

Sync this with a new branch called development in GitHub (in the same way you synced the master file. However, this time in ‘Branch’, add development and change the Path in ‘Git Repo’ to match the master one (highlighted).

Create a Feature Branch

To create a feature branch, a developer will clone a copy of the code from the development folder into their own workspace. In Databricks, you have the option to clone a notebook by selecting the tiny arrow next to the notebook. It will give you the option of where you want to put it.

Make a new folder for the feature development (e.g jo_change_c_value) and clone the notebook into there.

Once the notebook has been cloned, we will then sync it with a new feature branch folder in the same way as the image above. In this example, I create a new branch under ‘Git Preferences’ called ‘jo_change_c_value’ and sync my notebook.

I’m then going to change the code and set the c value equal to 4.

a=1
b=2
c=4

print(a)
print(a+b)

Click on save on the right hand side and it will ask you to save and additionally commit changes to GitHub if you want. Save the revision.

Make a PR to Development branch

You will see the change in GitHub.

Click on the ‘Compare & pull request’ and you will see an overview of the changes. In this example, I am asking to push changes to the development branch. This is just for good practise, if you only have a master branch then just ask to merge to there.

Press the green button that says ‘Create Pull request’.

You will then see the following page.

Click ‘Merge pull request’.

Now head to your development notebook in Databricks.

This is a bit odd but your changes will not immediately be visible (not sure why Databricks does this… if anyone does then let me know). On the right hand side in revision history, you will see the second to top record says Commit and then a number.

You need to click on the Commit one and this will be your newly pushed code.

Make a PR to master branch

To sync up the development and master branches, just follow the same process as above. As mentioned, ideally you would have some policies in place so that there is some sort of peer review process on PRs. However, that’s outside the scope of this post.

Databricks Version Control summary

Hopefully I have shown you how to version control for single branch personal and for multi user branching approaches. In my honest opinion, it’s not the most user friendly and there is room for human error (especially with the manual entry of folder paths). Further, it’s not very automated and this could be frustrating.

A better approach would be to employ a CI/CD approach. I’ll create a follow up post on this.

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