Exploratory: Enable volumes mounting in functions

[martindekov]

Enabling volumes to be mounted in function's file
system using annotations

Signed-off-by: Martin Dekov [email protected]

Disclaimer

This PR is exploratory and not solution discussed with the community.

Description

Functions can now mount volumes with this PR

Motivation and Context

• I have raised an issue to propose this change (required)

I needed the functionality and decided that this can be used by someone inspiration as part of the profiles support: #586

Also was suggested in:
openfaas/faas#1178
and:
openfaas/faas#320

This POC does exactly that.

How Has This Been Tested?

Image in:
martindekov/faas-netes/0.0.2

With function applying the following annotations:

...
    annotations:
      com.openfaas.volumename: "some-pv-storage"
      com.openfaas.pvcname: "some-claim"
      com.openfaas.pvcmountpath: "/some/directory"
...

The function's deployment had those fields:

...
        volumeMounts:
        - mountPath: /some/directory
          name: some-pv-storage
        - mountPath: /var/openfaas/secrets
          name: some-projected-secrets
          readOnly: true
      dnsPolicy: ClusterFirst
...
      volumes:
      - name: some-pv-storage
        persistentVolumeClaim:
          claimName: some-claim

...

And the volume was mounted successfully.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• POC not to be integrated or

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.

[alexellis]

Just a thought here. If this was added, would it cover every use-case if only one volume was supported per function?

[alexellis]

You'd have to handle updates too, if someone wanted to remove a volume that was already attached.

[alexellis]

This adds a volume even if one isn't configured, so you should set up the slice outside of this piece of code. ideally in a method to create it.

[alexellis]

Same as comment above

[martindekov]

Just a thought here. If this was added, would it cover every use-case if only one volume was supported per function?

Added this as POC if we want to merge it in master I can bring this in a better state.

[martindekov]

I will clear the shortcomings. I am aware of those but was not sure whether we want this to enter master. I suppose we do want to integrate the change and I will update the PR and fix all issues you mentioned. For the question whether only one volume is supported per function - yes this is the main idea. We might be able to extend this with wildcard annotation. So the key of the annotation itself suggest the volume name path etc. But I believe this would not be needed, at least I don't need more than one volume mounted.

[alexellis]

I think you should work to fix these basic issues, since you've gone ahead with a public PR, we can at least have it at a quality that anyone who lands here can test it or try it out. Would you be open to fixing up the initial feedback?

[martindekov]

I will close this, but will continue refining it and will keep the change in the branch.