On Tue, Dec 03, 2013 at 10:00:02AM -0500, Michael H. Warfield wrote: > On Tue, 2013-12-03 at 12:49 +0100, Harald Dunkel wrote: > > Hi folks, > > > do you think it would be possible to make the path set by > > -P/--lxcpath or in the config file a _real_ path, e.g. > > > lxc-ls -P /data1/lxc:/data2/lxc --fancy > > > ?
I'd recommend not using that kind of confusing syntax (e.g. what if I actually have a directory called /data/lxc: ?). Instead if we are to implement such a feature, we should be consistent with what we've been doing in the past and allow for "lxcpath" to be present multiple times in lxc.conf and for -P to be passed multiple times on the command line of all of our binaries. > > You had me confused for a brief moment, referring to this as a "_real_ > path" and I had to think about it for a bit. We have a problem with > ambiguity in the language where "path" can mean multiple things. It can > mean a singular absolute file system path to a file on a file system or > it can mean a delimited set of paths as in the PATH or LD_LIBRARY_PATH > environment variables. Both are equally "_real_" it's the context of > the utilization that makes the difference. One specifies a definitive > location while the other describes a "search path" to be processed. > You're suggesting changing the lxcpath from an "absolute path" to a > "search path" concept. Interesting. Intriguing. > > But... I see your point and it's an interesting idea. It has > possibilities. It also has the potential for ambiguous or confusing > behavior for some commands such as "lxc-start" or "lxc-create" where you > really want to specify a definitive location aot a search path (though, > I could see the use for a search for lxc-start (find the first stopped > container in a PATH stanza that's can be started - would that be safe?). > I guess lxc-create could settle on the first location it could write to > (placing user directories earlier in the path to control priority). > > Worse would be the case of lxc-stop where there were multiple containers > with the same name only different lxcpath locations within the greater > search string. That could get ugly and non-deterministic. This could > certainly be beneficial to things like lxc-ls where containers are > scattered between different locations. > > In that case, it might also be useful to utilize an LXC_PATH environment > variable in addition to the -P/--lxcpath command line options and config > file options. > > That's a very interesting idea that I would support if we could work any > various ambiguous behaviors for all the commands in a way that did not > result in user confusion. > > One thing I would NOT like to see is a situation where some commands > (lxc-ls) take a search path while some commands will only accept an > atomic absolute path. That sort of confusion would not end well. > > > This could help to support HA scenarios based on DRBD or > > a network file system, for example. If one LXC server > > dies, then a fallback host could take over the abandoned > > /data2/lxc in parallel to its own /data1/lxc directory. > > > Regards > > Harri > > Regards, > Mike > -- > Michael H. Warfield (AI4NB) | (770) 978-7061 | m...@wittsend.com > /\/\|=mhw=|\/\/ | (678) 463-0932 | http://www.wittsend.com/mhw/ > NIC whois: MHW9 | An optimist believes we live in the best of all > PGP Key: 0x674627FF | possible worlds. A pessimist is sure of it! > > ------------------------------------------------------------------------------ > Rapidly troubleshoot problems before they affect your business. Most IT > organizations don't have a clear picture of how application performance > affects their revenue. With AppDynamics, you get 100% visibility into your > Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349351&iu=/4140/ostg.clktrk > _______________________________________________ > Lxc-devel mailing list > Lxc-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/lxc-devel -- Stéphane Graber Ubuntu developer http://www.ubuntu.com
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