CODEWITHSUNDEEP
kuberneteskubernetes-deployment
TigerBear
TigerBear

Reputation: 2844

Kubernetes Share existing directory between pod containers

I have container A with a directory like "/public/shared". Container b which is a reverse proxy running in the same pod needs access to this directory.

How can I share these? My understanding of sharing a volume is that it is either an exiting external volume/directory, or an empty directory. In this case I want to share an existing directory in container A without creating an external/additional volume.

Also, I know it is possible to adjust container A so that it copies its data on startup, or to have it expose this via a REST API. Without going into detail, I would like to avoid touching the container A image and just accomplish this with just modifying the deployment YAML. For example, via copying. But copying uses

command: ["/bin/sh"]
args: ["-c", "cp -r /public/shared /public/mounted"]

And this seems to overwrite the default startup script in the pod if I understand correctly.

Upvotes: 0

Views: 201

Answers (1)

TigerBear
TigerBear

Reputation: 2844

Turns out you can add in a lifecycle command. This fixes it by copying into the empty dir without affecting the application startup. I feel like this still isn't great as it isn't guaranteed to run before startup. I guess I can also add a readiness probe to make sure these files are there. If anyone else has a better solution, I would be interested in seeing it:

          lifecycle:
            postStart:
              exec:
                command: ["/bin/sh", "-c", "cp -r /public/shared /public/mounted"]

Upvotes: 0

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