Related to https://github.com/apple/container/issues/1251
Change to sharing in the parent directory, and then bind mounting in the
file into the container. This has the unfortunate reality of being less
secure, but the current approach is burdended by a couple things,
namely:
1. You can't share in files that are on a different volume
2. There is a Virtualization bug that causes spurious errors when trying
to open the file.
I've added a doc to go over the approach we've taken, and some
workarounds if the approach is not satisfactory.
"clean up" is a verb, and "cleanup" is a noun. There are several
examples of the incorrect usage of "cleanup" as a verb in this
repository, including one in the public API (`cleanupOrphanedBlobs`).
For this public method, I've added a deprecation notice to the name with
the incorrect usage.
Fixes#79
This adds support for single file (virtiofs based) mounts to the two
main container types. This is transparent, and doesn't need to be setup
by a user, so there is no visible API change. Virtiofs does not support
single file mounts today, and it would be less than ideal from a
security standpoint to just expose the parent directory of the file to
the vm and then bind mount in the file, so we chose the following:
1. Create a temp directory the container types will manage.
2. Hardlink in the file we want.
3. Share that tempdir into the vm.
4. Finally bind mount in the file into the container.
The main goal I wanted for this is to leave the logic out of the
`VirtualMachineInstance`. I really want this to just be a little dance
the container types do, and leave the vm out of it. Because of that,
most of the logic is shoved in a new `FileMountContext` type that does
the dirty tricks of rewriting what the user asked for to be a bind mount
from a temporary holding spot we'll use in the guest for these temp
directories.
One of the downsides to this is today the tempdirs are solely on the
main volume, so cross volume will need to copy the file to the tempdir,
so writes won't get written back.
Co-authored-by: Dean Coulstock <d_coulstock@apple.com>
Co-authored-by: Jaewon Hur <hurjaewon@snu.ac.kr>
Michael Crosby