Hola,
Thanks for the correction. I was thinking along the lines of gmetric
flags rather than functions.
Still, I'm trying to add a cmdline/config option to make gmond appear to
be reporting for a different host. After some code digging it seems to
me that the receiving gmond determines the "hostname" value by seeing
where the connection comes from rather than by looking in the message
payload for some HOST tag. This changes things from "trivial" to
"where's my coffee"
To get the functionality I want I was thinking along creating a new
metric called "hostname" as an override (when it exists). This raises a
few questions:
1. Does that make sense at all?
2. Would it break backwards compatibility?
3. The hosts hash is indexed by IP - if a supplied hostname doesn't
resolve would it be legitimate to just throw away the data and
issue a warning?
4. What's the purpose of this: apr_gethostname( myname,
APRMAXHOSTLEN+1, global_context);
5. I'm sure there's a whole lot more I haven't tripped over yet...
Thanks,
Alex
matt massie wrote:
> it is possible and not too painful.
>
> path #1: use XDR directly in your application
>
> you'll need ./lib/protocol.h and ./lib/protocol_xdr.c from the ganglia
> distribution.
>
> in your application, you need to fill in a Ganglia_gmetric_message
> structure and then send it using XDR to your multicast/unicast
> channel.. for example...
>
> ======= start code ============
> Ganglia_gmetric_message message;
> /** fill in the strucuture ... */
>
> XDR xdrs;
> char msgbuf[BUFLEN];
> xdrmem_create(&xdrs, msgbuf, BUFLEN, XDR_ENCODE);
> xdr_Ganglia_gmetric_message(&xdrs, &message);
> u_int len = xdr_getpos(&xdrs);
> ======= end code =============
>
> that's it! now your message buffer (msgbuf) has len bytes of data to
> send package in ganglia XDR format.... ready to send to your favorite
> gmond.
>
> path #2: use the helper functions in libganglia
>
> if you open up ./gmetric/gmetric.c you'll find that it just uses the
> libganglia helper functions to send message. these helper function
> will parse the local gmond configuration file, setup the channels,
> populate the Ganglia_gmetric_message structure and send it for you.
>
> let me know if this helps.
> -matt
>
>
>
>
>
> On Apr 11, 2006, at 9:07 AM, Alex Balk wrote:
>
>> Hi Egan,
>>
>>
>> That's not possible at this point.
>>
>> It's an interesting idea, though. I'd go with pushing the data into
>> gmond if you're doing unicast, though. That way when gmetad polls it,
>> the data would get written out to the rrds without having to modify any
>> gmetad code.
>>
>> If you're doing multicast, it would probably be different (I'm not sure
>> if it'd be practical or at all possible, as all gmonds hold all the
>> data)... worth checking out though.
>>
>>
>> Hopefully I'll get to check this out this weekend.
>>
>>
>> Cheers,
>>
>> Alex
>>
>>
>> Egan Ford wrote:
>>
>>> I have a large cluster and I would like to collect HW data, but do
>>> not want
>>> to call gmetric on each node, e.g. today each node has to run:
>>>
>>> gmetric --name temp --value 30 --type int16 --units Celsius
>>>
>>> Since I can get the data without impacting the OS, how can I get the
>>> data
>>> into gmetad? Something like:
>>>
>>> gmetric --name temp --value 30 --type int16 --units Celsius --host
>>> node1
>>>
>>> Thanks.
>>>
>>>
>>>
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