On Wed, 13 Nov 2013 14:41:55 -0500 Stéphane Graber <stgra...@ubuntu.com> wrote:
> Hello, > > We recently got reports of the recent changes to lxc-info breaking > existing scripts. > > While discusing those issues, I noticed a few points that I think are > worth discussing and addressing, I'm going to postpone alpha3 until > that's done as the current state of things would break quite a bunch > of scripts. > > == confusing -n behaviour == > Since Dwight's last change, -n now accepts a regular expression, > which I believe is the only case where it does. That seems fairly > unintuitive and redundant with what lxc-list for example provides. > This also brought on the next problem. I did this because I wanted to be able to get info on all/some containers and the previous precedent for that: lxc-wait, even before I messed with it ;) used regex matching. I think Serge mentioned that he didn't like regex's there, and would prefer glob fnmatch style matching. I'm not particularly tied to lxc-info being able to handle multiples though, so I'm fine if we want to rip that out :) Also I don't think lxc-ls has a way to list all containers, (ie. both defined and active) but it would be easy to have it do that now. > == change of behaviour when one of the filter is passed == > In the past, someone could do "lxc-info -n p1 -p" and trivially > retrieve the PID. > > The new behaviour instead returns: > Name: p1 > Pid: 19446 > > Even though I didn't ask for the container's name. "pid" was also > renamed to "Pid", breaking anyone attempting to grep for the entry. I agree name shouldn't be printed in that case, or any time a specific thing is asked for. I actually looked for trouble the name changing might cause, and the only potential case I saw in the shipped lxc stuff was lxc-test-ubuntu, but it was okay because it called lxc-info -i and awked out the second column, so renaming "IP" didn't break it. You are correct though that external scripts might've broken though. If we're going to say that lxc-info's output is "stable" though so folks can grep out which parts they want, then maybe we don't need options like -i and -p ? > == --state-is option is redundant == > The state-is option always seemed a bit odd to me, in fact, it's > absolutely identical to "lxc-wait -t 0 -n <name> -s <STATE>" and I > don't really think it has its place in lxc-info. I'd suggest we just > remove it entirely (yes, that'll break some scripts). Agree, especially considering it doesn't even seem to work right now. $? seems to always be 0 for me. > I'm sorry I didn't think about those problems when reviewing the > recent changes to lxc-info, but hopefully it's not too late to > correct some of that. Sorry for introducing these problems :( > > So my suggestion for lxc-info in LXC 1.0 are: > - Only support one container and make -n mandatory, fail with an > error if the container can't be found. > - Drop --state-is entirely and tell anyone who used it to use > lxc-wait instead. > - Only print Name: if none of the filters are passed > - Make the combination of -H + a single filter only return that > value, so that "lxc-info -n p1 -P -H" will just return 19446 without > any formatting. Recommend doing that to anyone parsing lxc-info's > output. > - Have -H also apply to the general formatting, simply printing > <key>: <value> when passed. That all sounds fine to me. > With those done, there will still be breakage for users of alpha2 > upgrading to alpha3, but that should at least ensure no more surprises > after that point and a more script friendly command. > > > Thoughts? > ------------------------------------------------------------------------------ DreamFactory - Open Source REST & JSON Services for HTML5 & Native Apps OAuth, Users, Roles, SQL, NoSQL, BLOB Storage and External API Access Free app hosting. Or install the open source package on any LAMP server. Sign up and see examples for AngularJS, jQuery, Sencha Touch and Native! http://pubads.g.doubleclick.net/gampad/clk?id=63469471&iu=/4140/ostg.clktrk _______________________________________________ Lxc-devel mailing list Lxc-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-devel
