On Monday 12 November 2012 10:50:57 Dejan Muhamedagic wrote: > Hi Arnold, > > On Sun, Nov 11, 2012 at 07:37:29PM +0100, Arnold Krille wrote: > > On Sun, 11 Nov 2012 18:37:04 +0100 Dejan Muhamedagic > > > > <deja...@fastmail.fm> wrote: > > > On Fri, Nov 09, 2012 at 05:22:08PM +0100, Lars Marowsky-Bree wrote: > > > > On 2012-11-09T14:06:29, Dejan Muhamedagic <deja...@fastmail.fm> > > > > > > > > wrote: > > > > > > And also doesn't really help with getting the state/readiness of > > > > > > services the guest might provide. > > > > > > > > > > Isn't it that one gets a login prompt only once the host reached a > > > > > certain run level? > > > > > > > > Services may start in the background. The console may either be > > > > text, graphical, or network only. > > > > > > Hmm, I have yet to see a Linux/UNIX host without a console. And > > > that means quite some time ;-) > > > > While (almost) all systems have some kind of console, not all systems > > stay at a text-console during runtime. > > It seems like you are mixing things up. This is not about > watching a computer monitor. On Linux there's always a console > tty.
1) There are linux systems without a tty. 2) Watching the first / whatever tty is not telling you anything. Some systems don't run a login on tty1 but show tty1 after start, some systems switch to graphics (yes, virtual machines do that too), some machines show a nice menu letting you choose your language and stuff. > > If you want to watch a > > linux-terminal-server, its not a text-console that is the primary > > screen. > > > > And then watching the text-console for a login:-prompt tells you that > > the machine is up. "Pressing" enter tells you that the login-process is > > still answering. But that doesn't tell you whether the webserver on > > that machine is still working correctly. > > That is not the point. > > > Its not even telling you if > > the machine is reacting to network stuff. All it tells you is that some > > kind of system is started. So its actually only a little more then > > "virsh list |grep <machinename>" tells you. > > > > Imho watching the console for monitoring a machine is as useless as it > > can get. > > It tells you that a host is at a certain runlevel. The host is > ready for business, i.e. all other service at the particular > runlevel have been started. Otherwise, it wouldn't make sense > that it offers a login prompt. I don't know how it is with > systemd, perhaps systemd functions differently. Whether a > particular service is functioning properly or at all is up to the > monitor resource to find out. Watching the/a tty of a linux machine is not telling you anything in general. It's only us humans that can make some sense of what we see there. For a machine to watch another generic machine via tty its to much variables and to much engineering needed. BTW: Some machines present the login:-prompt (text and graphics) well before everything is started, suse and ubuntu did that some three-five years ago already. And actually I don't care (cluster-wise) at which runlevel the webserver is, it has to serve pages at port [80,443] otherwise its useless and has to be killed and restartet. No monitoring of any tty can tell me that... Have fun, Arnold
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