Re: Add Metavariable $imagename

[Mike Dawson <mike.dawson@cloudapt.com>]

Thanks for the feature request Mark!

To illustrate where my understanding ends, here is a patch to stub in 
this functionality:

 From 137ebc2d5326ca710a5e99e2899fd851b02c10f7 Mon Sep 17 00:00:00 2001
From: Mike Dawson <mdawson@gammacode.com>
Date: Wed, 4 Sep 2013 11:39:05 -0400
Subject: [PATCH] Update config.cc

---
  src/common/config.cc | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/common/config.cc b/src/common/config.cc
index 5c64f4e..89ac0ee 100644
--- a/src/common/config.cc
+++ b/src/common/config.cc
@@ -929,7 +929,7 @@ int md_config_t::set_val_raw(const char *val, const 
config_option *opt)
  }

  static const char *CONF_METAVARIABLES[] =
-  { "cluster", "type", "name", "host", "num", "id", "pid" };
+  { "cluster", "type", "name", "host", "num", "id", "pid", "image-name" };
  static const int NUM_CONF_METAVARIABLES =
        (sizeof(CONF_METAVARIABLES) / sizeof(CONF_METAVARIABLES[0]));

@@ -1007,6 +1007,8 @@ bool md_config_t::expand_meta(std::string 
&origval) const
  	  out += name.get_id().c_str();
  	else if (var == "pid")
  	  out += stringify(getpid());
+	else if (var == "image-name")
+	  out += "TBD"
  	else
  	  assert(0); // unreachable
  	found_meta = true;
-- 
1.8.4


Obviously, the I'm stuck at "TBD". I'll finish it if someone could point 
me in the right direction.

Thanks,

Mike Dawson
Co-Founder & Director of Cloud Architecture
Cloudapt LLC
6330 East 75th Street, Suite 170
Indianapolis, IN 46250

On 9/4/2013 11:07 AM, Mark Nelson wrote:
> On 09/04/2013 09:46 AM, Mike Dawson wrote:
>> There are currently a few metavariables available for use in ceph.conf:
>> http://ceph.com/docs/master/rados/configuration/ceph-conf/#metavariables
>>
>> In addition to those listed in that document, $pid was added in Bobtail.
>> That allows me to get RBD admin sockets for libvirt/qemu guests by
>> specifying
>>
>> [client]
>>      admin socket = /var/run/ceph/rbd-$pid.asok
>>
>> in /etc/ceph/ceph.conf. That works well for VMs with a single volume,
>> but it does not work for VMs with multiple volumes. With multiple
>> volumes, the admin only lists data on the last volume specified, leaving
>> me unable to monitor stats on any volumes other than the last.
>>
>> I imagine you could specify a unique admin socket for each volume on the
>> command-line that libvirt uses to spawn qemu, but that seems like a pain.
>>
>> Is it possible instead to add a metavariable that would expand to the
>> image name? This way, my ceph.conf would look like
>>
>>
>> [client]
>>      admin socket = /var/run/ceph/$imagename.asok
>>
>> and I would end up with admin sockets like:
>>
>> /var/run/ceph/rbd-volume-0025b693-6230-443e-ad6a-3aa43efdd648.asok
>> /var/run/ceph/rbd-volume-009228f3-b8d7-4f3c-8458-0cdbd4809dc6.asok
>>
>> # rbd -p volumes ls
>> volume-0025b693-6230-443e-ad6a-3aa43efdd648
>> volume-009228f3-b8d7-4f3c-8458-0cdbd4809dc6
>>
>> I'd be happy to provide a patch if someone could give me sufficient
>> guidance on how/where to add this functionality.
>>
>
> Created a feature request in the tracker for this:
>
> http://tracker.ceph.com/issues/6228
>
> Mark