Thursday, June 3, 2021

How to backup Azure DevOps code repositories

Under "shared responsibility in the cloud" model, the client is always responsible for its own data. Azure DevOps, as a SaaS offering, ensures that underling infrastructure (compute, network, storage, etc.) is highly available and the client's data is geo-replicated. You can find all the details how Azure DevOps protects your intellectual property here. However, you might want to have an "offsite" copy of your repositories for archiving, doomsday disaster recovery, or any other reasons.

I've used an approach described by Charbel Nemnom in his blog post. The process was enhanced to cover ALL code repositories within Azure DevOps project (TFVC including) and remove the dependency on the user's PAT.

The backup pipeline

We will use classic build pipeline with schedule trigger to automate the backup process. The YAML pipeline is not suitable for the next reasons:

  1. We want to use native functionality to checkout source code from TFVC
  2. TFVC doesn't support YAML pipelines (we want to backup ALL repositories)
  3. Single pipeline will automatically cover all curent and future Git repositories without any extra steps required
The pipeline use existing project's TFVC repository as a source:

Here, we use mapping feature to checkout code stored in TFVC into subfolder. The pipeline tasks will create extra subfolders for each Git repository within sources directory on the executing agent.

Note. If your project doesn't have TFVC repository, you need to create one:

Select "Empty job" as a pipeline template. In this state, we have a pipeline that will checkout TFVC code. 

Task 1. Download Git Repos



We need to add a task that will download all Git repositories to the agent. The pipeline will use next PowerShell script that utilizes VSTeam module to perform Git repositories discovery and cloning.


Couple words about security. The script uses build service identity to access Git repositories. In order this to work, two Azure DevOps settings need to be changed.
  1. The pipeline job needs to have access to the OAuth token at the runtime:


  2. The job needs to be authorized to access all repositories in the project (otherwise the pipeline will 'see' only explicitly referenced repositories, see documentation for details):


Task 2. Archive source code

This a standard task that will put all the files collected in the agent's source folder into a ZIP file.

Task 3. Publish Pipeline Artifact


In this demo, we just publish generated repositories archive back to Azure DevOps. In the real world scenario, there are multiple options of what can be done with this archive file:
  1. Upload to the cloud storage service of your choose
  2. Copy to the file server in the corporate network where the regular backup process will take care of the long-term retention
  3. etc.

Trigger


The pipeline is scheduled to perform nightly backups. Checkbox "Only schedule builds if the source or pipeline has changed" must be un-checked to ensure the schedule is not affected by no changes in TFVC repository.

Restore

The Git repositories restore process is described in the blog post I've referenced in the beginning of this article. The TFVC repository restore is as easy as copy TFVC folder content from archive file.

Note about TFVC

TFVC is centralized source control by its nature. It stores the files history on the server. For this reason, the TFVC backup produced by above process is a repository snapshot (at the backup time). The quasi-history can be build from the backup files produced on different days.(Probably, it would be the least of your worries if you will actually have an actual need to restore these repos).

Pipeline execution

My demo project contains next repositories
The downloaded pipeline artifact (the ZIP file) contains TFVC snapshot and the 'mirrors' of the Git repos:

Conclusion

I hope this article will help you to establish centralized source control backup for Azure DevOps and will let you (and your boss) to sleep well knowing that precious intellectual property has an extra layer of protection.




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How to backup Azure DevOps code repositories

Under " shared responsibility in the cloud " model, the client is always responsible for its own data. Azure DevOps, as a SaaS off...