What is dangerous about mounting home writeable?

[tmewett]

In the default config, there is:

mounts:
  - location: "~"
    # CAUTION: `writable` SHOULD be false for the home directory.
    # Setting `writable` to true is possible, but untested and dangerous.
    writable: false

I was wondering what kinds of failure modes we should expect from a writeable home, and if any data loss has ever been observed. It would help users evaluate the risks. E.g. am I only worried about individual files being corrupted if errors occur? Or my entire home being deleted by some freak mounting issue? I appreciate this may deliberately err on the side of caution and failures are not well-known, but any info would be great. Thank you :)

[jandubois]

I believe this is just being cautious in general. In a way any software can cause catastrophic data loss.

Just as a point of reference, both Rancher Desktop and Colima (both of which use Lima under the hoods) have switched to mounting the home directory as writable for practical considerations.

@AkihiroSuda Will we ever change the default setting for Lima? If we want to, what would be the condition to enable this? If we say we don't trust sshfs, then we obviously will have to wait until we switch to something else. But otherwise I'm not sure what we would be waiting for.

[AkihiroSuda]

@AkihiroSuda Will we ever change the default setting for Lima? If we want to, what would be the condition to enable this? If we say we don't trust sshfs, then we obviously will have to wait until we switch to something else. But otherwise I'm not sure what we would be waiting for.

We may reconsider the default after we get virtio-9p-pci.

[afbjorklund]

What is the main use case for mounting the home directory ? Is it to access credentials from ~/.docker and ~/.ssh ?
Or is to access the current project files, which are just assumed to be stored somewhere under the home directory ?

Just wondering, seems like most the files that I edit are under /home/anders.linux rather than the remote /home/anders
Even if read-only, there are still the security and performance implications of exporting the home directory from the host.

[afbjorklund]

In a way any software can cause catastrophic data loss.

I think data loss on the virtual machine is to be "expected"...
Not so on the host itself, which could be assumed to be separate.
Think it was even worse before* though, when all users were exported.

* as in Docker Toolbox, which exported /home /Users /C/Users