nerdctl silently ignores tmpfs volume configuration

[gtsiam]

Description

nerdctl compose up fails to configure containers with tmpfs volumes and silently creates an anoymous volume instead.

My SSD is not very happy.

Steps to reproduce the issue

1. Create a test compose file with a tmpfs mount:

name: test
services:
  test:
    image: alpine
    volumes:
      - type: tmpfs
        target: /tmp/cache
        tmpfs:
          size: 1073741824 # 1GB

2. Run nerdctl compose up.

Describe the results you received and expected

An anonymous volume is created, instead of the tmpfs configured in compose.yaml:

nerdctl inspect test-test-1 | jq '.[].Mounts[]'

{
  "Type": "volume",
  "Name": "ee5270c6228ed7b8f75b486c151454c68954146ad700063c93754d0b0e6aaf91",
  "Source": "/var/lib/nerdctl/1935db59/volumes/default/ee5270c6228ed7b8f75b486c151454c68954146ad700063c93754d0b0e6aaf91/_data",
  "Destination": "/tmp/cache",
  "Driver": "local",
  "Mode": "",
  "RW": true,
  "Propagation": ""
}

What version of nerdctl are you using?

nerdctl 2.1.6

[ZaidMarwat]

Hi! I’m a computer science student at the University of Texas at Austin, and my teammate @akoul-05 and I are looking to contribute to nerdctl for a virtualization class assignment. We need to tackle up to three issues in the repository, so you may see us commenting on a few others as well.

This tmpfs-mount behavior seems like an interesting problem, and we’re trying to understand the context a bit more before deciding if it’s something we can take on. Do you happen to know whether this is a known limitation of nerdctl compose or something that should work according to the current design? And is the expected behavior simply parity with Docker Compose’s tmpfs handling?

[gtsiam]

Sure, happy to have you.

Do you happen to know whether this is a known limitation of nerdctl compose or something that should work according to the current design? And is the expected behavior simply parity with Docker Compose’s tmpfs handling?

It's a bug - not sure what a "known limitation" even means here. Sure, it's always been broken as far as I can tell, is that a "known limitation"? Odd question.

Anyway - for the example I provided, it should at the very least throw an error here, not silently do something I didn't tell it to do. This is a general computer engineering principle - if software does shit you didn't tell it to do, it's a bug.

Relevant documentation here (which yes, is intentionally identical with docker's compose specification).

Good luck!

[haytok]

Hi, Team
If no one else is working on it, could you assign it to me?