[hobbit] Sending data from script to an rrd

[Hubbard, Greg L]

Rob,

The problem is that this is scattered across several different places in
the Hobbit architecture.

1. Detecting the numbers.  In a client-side (or server-side, though more
rare) script, you do whatever you need to do to get some numbers.  You
format these numbers and send them to Hobbit.  All Hobbit is looking for
is the header line where you give it a color.  The rest is just text
that Hobbit will faithfully store and repeat back to you as date under
the column you have selected.  Knowing that only the first line is
important, then you can do WHATEVER you want to show your numbers.
Knowing that you will be parsing this text when you receive it, it is
very helpful to put the data in a format that is easy to recognize and
parse later, but is still readable to the human eye.

Another note -- you need to do all of this on new columns -- don't try
to augment the existing Hobbit tests.

To debug: simply eyeball the text that is listed as column detail for
your test.  If Hobbit is getting it, and assigning a color, then you are
out of the gate.

2. On the Hobbit server, you write a custom parser script.  This script
is called with three parameters -- the column name (aka test name), the
node name associated with the test, and a file name.  What your script
should do is branch appropriately according to the test name, and then
read the file, parsing it as needed.  The script can be written in any
language (Perl comes to mind if you don't like shell).  But keep in mind
that there is ONLY ONE parsing script allowed, and it needs to be able
to service all of your custom tests.

When you find the numbers you want for your test, you simply write to
STDOUT the sequence that Hobbit is looking for to put your data in RRDS.
ANYTHING else that you want to say in your script needs to be directed
to a log file, or some other place.

You have to tell the Hobbit server to use your script -- this requires
modification of the hobbitlaunch file to change the parameter list for
the hobbit_rrd modules.  Notice that there are two of them -- one for
data, and one for status.

To debug: run your new test script by hand, supplying a bogus node name,
the name of the real test, and the name of a file.  I found it helpful
to snag all of the test from the column detail and save it in a file,
and then use that file as the file parameter.  All you should see come
out of your script is the RRD language -- first the DS statements, then
the file name, and finally the data record.  You can write it all to one
RRD, or to several, depending on what you write out.

3. Now that RRD's are being created, you have to go and create graph
definitions in hobbit-graph.cfg and you have to tell Hobbit about them
so you can see them.  You can choose from the wealth that is already
there to get examples or "borrow" code.  You will need to consult the
RRDTool documentation to understand these graph definitions, because
Hobbit graph is simply passing these definitions through to RRDTool for
graphing.

Now you need to update the Hobbit server configuration to include your
graphs in both lists -- TRENDS and TEST2RRD.  I could not keep things
straight, so I ended up calling my graph definitions by the same name as
my tests.  So for test "foo" I create a graph definition "foo" instead
of "bar".

To debug: First, are the RRD entries being created?  You should see them
in the data directory underneath the name of the host where the
client-side test is being run.

Next, is there data being written to the RRD?  You can dump the contents
with RRDTool, but I forget the syntax.  All you are looking for is that
your data is ending up in the right place.

Next, can you see your graphs?  If you don't see a graph at all on your
test page, then you probably have not identified it correctly to the
Hobbit server in the hobbitconfig.  If you see a broken link where you
expect a graph, the problem is probably with your hobbitgraph.cfg file
-- you made an error specifying the graph.

I have created 7 or 8 custom tests with graphs and everything.  The
first one took several days, then I got a lot faster.

I wish I had time to be more exhaustive in the instructions...

Good luck!

GLH


-----Original Message-----
From: Rob Munsch [mailto:rmunsch at solutionsforprogress.com] 
Sent: Wednesday, October 18, 2006 3:03 PM
To: hobbit at hswn.dk
Subject: Re: [hobbit] Sending data from script to an rrd

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Ralph Mitchell wrote:
> On 10/18/06, Rob Munsch <rmunsch at solutionsforprogress.com> wrote:
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>> Hubbard, Greg L wrote:

> Script #2: is executed by hobbitd_rdd via the --extra-script option.
> This one extracts relevant information from the incoming status report

> and echoes out the RRD creation parameters, the RRD file name, and the

> data to stuff into the RRD.  Hobbit_rrd reads that and does what's 
> necessary to save the data in an RRD.

maybe i'm not being clear.  It's been a long day...

I understand that the goal is to get data to RRD in a format it likes
with data and filenames it understands.  That part is obvious.  The
concept is not the issue; i know i want to graph things!

What is not obvious is where to warn hobbit that this info is coming and
precisely how to send that info; "echo" clientside was, i thought, read
by the client's hobbitd as in a wrapper, but i guess not..?

- --
Rob Munsch
Solutions For Progress IT
www.solutionsforprogress.com
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