On Wed, Jan 26, 2011 at 12:56:54AM -0800, Joel Krauska wrote:
> On 1/25/11 10:48 PM, Willy Tarreau wrote:
> >Hi Joel,
> >
> >On Tue, Jan 25, 2011 at 01:29:11PM -0800, Joel Krauska wrote:
> >>I'm not sure if people have asked for this, but I would love a custom
> >>field/column in the Stats Report web page.
> >>
> >>Specifically, I would like to be able to see my backend server
> >>version. This is a custom text string which I could provide a
> >>health-check-like URL to populate.
> >>
> >>Then the HAProxy stats page could be a one-stop page to watch during
> >>rolling upgrades of backends.
> >>
> >>Probably for easy customization, an external call to third party
> >>script would be ideal.
> >>
> >>Has anyone considered this before? Is there any way to hack existing
> >>features to do this?
> >
> >You should take a look at "stats show-desc". You can already use it to
> >report a section-specific string. You can then have your upgrade script
> >fill it from a config template. For instance :
> >
> >backend foo
> > stats show-desc @@foo.version@@
> >
> >Then replace @@foo.version@@ with whatever you like.
> >
> >Assuming you're in a secure enough environment to consider such things,
> >you should also take a look at "stats show-legends" which reports much
> >more information (eg: mode, IPs, cookie names, etc...). This is different
> >from what you asked for but will surely help troubleshoot issues if you
> >already feel concerned with the config version.
> >
> >Cheers,
> >Willy
> >
>
> Willy,
>
> I think you've described a per-backend description.
> I enabled stats show-desc, but that's a per backend feature, right?
>
> I'm looking for a per-server (subset of backend) field.
>
> Use case:
>
> backend pool foo has four servers: a,b,c,d
>
> initial state, all four servers are running code rev 22.
>
> I initiate a rolling upgrade, which includes a graceful shut, upgrade of
> code and graceful start of each server.
>
> The new code rev is 23.
>
> As I upgrade the code on each server from version 22 to version 23...
> It would be nice if HAProxy was able to poll a given URL to identify the
> unique version of each server to monitor the progress of the upgrade and
> confirm quickly/visually that all members of the same backend are in
> sync at the end of an upgrade....
>
> mid upgrade
> a - version 23
> b - version 23
> c - down (currently be upgraded)
> d - version 22
>
>
> It's sort of like a special case of a healthcheck, but for a given URI
> and displaying the output, not just if the check succeeded.
>
>
> Something you'd consider adding?
>
>
> In the meantime I've got my own little per server version table page
> that has this info, but it's very similar to the haproxy page....
> (pools and member servers)
OK I see better what you're looking for. Then you could already do
something like this using the health checks. Since the stats page
reports the health check response (eg: "200 OK"), the code which
handles the health check on the server could simply adjust the
response to report the version ("200 OK: version 1.12") and you'll
find it in the stats page.
Willy
