ch-fromhost option order

[rarensu]

ch-fromhost has two kinds of options according to its signature

ch-fromhost [options] [file_options]

the documentation doesn't define which of the options are "file options". In particular, the --dest option kind of looks like a file option to me, but since its in a third "category" all on its own, it's ambiguous.

Apparently, the order matters. If I put the --dest option after another option such as -p, the dest option is completely ignored.

I don't love that the options are only accepted in a certain order, but if it has to be that way, it should be really clear in the documentation which options have to come first.

charliecloud 0.33

[j-ogas]

Ah, yes, I too found it a little confusing initially.

-d should proceed a -p argument, otherwise -p will use the inferred injection directory. The idea for this is to be able to inject to both a custom path and the inferred path in the same injection call. For example:

$ ch-fromhost -p /opt/foo/lib64/libfabric.so -d /usr/bin -p /usr/local/bin/fi_info

In the above /opt/foo/lib64/libfabric.so will be injected to /usr/local/lib (inferred) and fi_info will be injected into the containers /usr/bin folder.

I didn't figure that out myself until I poked around the script; so yes, I agree the documentation needs some help here.

[j-ogas]

I think a better way to say this may be:

all --path arguments preceding --dest will use the inferred path; all --path arguments after --dest will use the specified path?

[rarensu]

That seems like an unnecessarily specific use case. I guess you can say that about the whole tool.

Fixing the documentation is a higher priority than refactoring the arguments, but if it was on your to-do list anyways to refactor the arguments, I thought you might like some feedback from someone who tried to use it in the wild.

I think I would rather if it worked like how bind mount works, where you go "source:dest" for explicit destinations. Yes, you'd have to repeat the destination for each file, but then it becomes pretty much impossible to misunderstand. I like that the bind mount syntax is maximally explicit.