Persistent volumes for workspaces
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### Proposal
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We have a vast amount of static, large, binary input files that are stored in a volume - and they would be very much needed in the workspace as is for testing, analysis, debugging, and development. They're quite awkward to be stored in a repository, or to be downloaded one-by-one to the workspace. Some files are a bundle - so multiple files are sometimes needed for the tasks that we are doing in the workspace. The files are too big to be stored reasonably in the image for the workspace.
However, currently GitLab does not let to mount persistent volumes to workspaces. This may be reasonable to enforce stateless workspaces. But to satisfy our needs we would like to mount a persistent volume, such as S3 or EFS volume, to the workspace when it is starting up to let the user to access the static files. This let's us to also list the files and navigate thru them nicely.
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