[question] Support for docker tmpfs mounts

[cetex]

We currently run a job which requires tmpfs for temporary storage (it writes around 5GB of data from one process every few seconds and reads it back multiple times into other processes, anything else than tmpfs is too slow, even zram is too slow and causes too much overhead)

I can't figure out if it's possible to tell the docker driver to mount a new volume of type tmpfs into the container right now, it seems like it's not possible as you only support "Volume type mounts" which i guess means predefined docker-volumes only?

I'd like nomad to support creating a tmpfs mount at a specified path in the container. The options i've found for doing this with docker are:

docker run --mount type=tmpfs,destination=/app ...

docker run --tmpfs /app ...

Potentially, extending the docker mounts support with a "type" flag and passing that through to the docker daemon should work well?

[chelseakomlo]

Hi, thanks for the feature request. Generic tmpfs support is in our future roadmap but is not currently enabled. See related ticket #3021.

Keeping this issue open to track future development- let us know if anything else comes up in the future.

[filipochnik]

What's the status of this feature? I was looking into implementing this.
@chelseakomlo what do you mean by "generic tmpfs support"?

[chelseakomlo]

Hey, thanks for the question. This is still in our future backlog.

By generic tmpfs support, we mean that users in the future will be able to create tmpfs mountpoints beyond only /secrets(which is what is currently supported).

[filipochnik]

But we are still talking only about the docker driver, right?

Will you accept a PR for this? If it doesn't interfere with your work I'd be happy give it a shot.

[schmichael]

@filipochnik I'm afraid we won't accept docker-only PRs for additional tmpfs support. It will be part of a larger cross-driver volumes effort in the coming months that will require scheduling changes. In particular we'll need the scheduler to account for additional memory allocated to the tmpfs.

Sorry for the bad news! We know our lack of generic volume management is a big pain point for some users and will be getting to it soon!

[filipochnik]

@schmichael Gotcha!
I was actually looking for a feature to contribute, I don't have an immediate use case for this personally. Anyway, thanks for answering :)

[schmichael]

@filipochnik Oh! Well in that case I'll do some digging and see if there are any fun issues in our backlog! :)

[filipochnik]

Awesome, thanks!

[Miserlou]

What's the status of this? This feature is useful to me.

[schmichael]

@Miserlou Coming in 0.9! Sorry for being slow to update the issue. Lots landing lately, and we've been updating issues and the changelog asynchronously.

See #4924 for details.

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