I didn't check the code, but I fear this is a more widespread issue than just --mnt-volume. If I recall correctly, most of current option parsing logic is just a split(,) + split(=). And the solution to that is probably agreeing on the separator, how to escape it (a custom \, or some broader "" quoting?) and then introducing a proper parser.

Ironically, a lot of the code actually parses these as CGI parameters, so you could theoretically use %-escaping. I don't think that's a very good idea, though.

Allowing escaping would be a little messy from a regular UX perspective because you'll have to double quote or double escape to get around the shell (--mnt-volume=..,source='"/foo/bar,baz"' type stuff).

Allowing an input of json for that field somehow would gain json escaping for free and would also be programmatically a bit easier to work with, but that's an even worse cli ux I think.

@euank I think I misread your initial suggestion, so my answer was a bit off-target, sorry for that.

I agree we should have some way of specifying a JSON runtime config, possibly allowing appc and oci formats in the future.

The problem with commas in CLI flags remains, though, and this is where I was suggesting escaping.

Braindumping mode: another option is a sed-like syntax, where the first character is a custom one and specify the delimiter. To be backward compatible we could switch to this mode only if the first character is in some specific range (eg. non-printable ascii, or non-alphanum). This would allow to keep CLI flags human-friendly while allowing programs to use something smarter (eg. 0x1e) as delimiter.

Yeah, I'm for fixing both.

My own braindump: another option would be to allow two ways to specify it, one with the commas, one with multiple flags. E.g.:

--mnt-volume-name=foo --mnt-volume-source "/foo/bar,baz" ...

However, that comes up with the problem of grouping flags. We already sorta have that with associating things to specific images, and we could do the same thing where the volume name must be first and other mnt flags after that associate with it..