[mrtg] Graphing Uptime

Fri Sep 28 23:11:34 CEST 2018

I am not sure yet what makes it go through BER, because if what you're saying is true, the HTML pages would just show a raw tick count for uptime if you use snmpwalk instead. The HTML generation just assumes that the data is already string, which is weird. It's taken me hours to get this far, as it's hard enough to use as it is! (Rather like a mailing list that helpfully makes you reply off-list!)

I don't want to reprogram MRTG, unless I were sure enough that I'd got it figured out to be able to commit a patch. (Not least because since Debian is so far behind.) I will have to consider my options .....

On 2018-09-28 22:05, Edwin A. Epstein III wrote (off-list, in reply to my accidental off-list replies):
> Hi Daniel,
> 
> I had forgotten that MRTG internally uses a different library and does not use snmpwalk. I've seen the error you gave us here many, many times in other gauges I've created. It's almost always due to a string being presented when an integer is expected.
> 
> You can force MRTG to use snmpwalk instead. I've had some very strange errors on some devices that were solved just by doing that. Prefixing any OID with WaLK causes it to use snmpwalk instead. CNTWalk I believe will also use snmpwalk, but count the number of entries received instead of the values. It's case sensitive, and requires it exactly like I wrote it. Of course, all of it is in the book.  
> 
> I appreciate that you want to reverse the engineer the code to make it graph uptime as an integer. The other ways I suggested will work too.
> 
> Good luck.
> 
> Sincerely, 
> 
> Edwin A Epstein, III 
> Rhinobee Internet Services 
> 707.237.7504 ext 209 
> 707.737.0288 Mobile
> 
> ----- Original Message -----
> From: "Daniel Beardsmore" <resident at telcontar.net>
> To: "Edwin A. Epstein III" <ed at rhinobee.com>
> Sent: Friday, September 28, 2018 1:36:37 PM
> Subject: Re: [mrtg] Graphing Uptime
> 
> Ah, right, there is some sort of "single request" option, and only if you choose to use that, might you want to disable pretty printing ...
> 
> I have no idea.
> 
> 
> On 2018-09-28 21:21, Edwin A. Epstein III wrote:
>> Hi Daniel,
>>
>> Yes that example was horribly bodged. I haven't inspected the code, but I suspect MRTG works with the value returned by SNMP. For example, I receive this:
>>
>> SNMPv2-MIB::sysUpTime.0 = Timeticks: (105630500) 12 days, 5:25:05.00
>>
>> That cannot be graphed because it is not a number. Everything that MRTG graphs must be turned into some number. The example is also horribly bodged because it's trying to use a bandwidth graph instead of a gauge. MRTG provides for graphing values like CPU load, Memory, and Free disk space. You really want to grab the most recent book as it will tell you how to construct these. I'll give you an example:
>>
>> Target[the_graph]:        1.3.6.1.4.1.32050.2.1.27.5.1&1.3.6.1.4.1.32050.2.1.27.5.1:snmp_community_name at 10.0.0.1:::::2 * -1.1034882
>> Options[the_graph]:       unknaszero,gauge,growright,nopercent,expscale,noo
>> SetEnv[the_graph]:        MRTG_INT_IP="No Ip" MRTG_INT_DESCR="n/a"
>> Colours[the_graph]:       ORANGE#dd8811,NONE#000000,VIOLET#0000ff,DARK GREEN#006600
>> Title[the_graph]:         Voltage Monitor
>> MaxBytes[the_graph]:      850
>> AbsMax[the_graph]:        850
>> XSize[the_graph]:         600
>>
>> All of these directives are explained in the book. The two most important ones are the Target and Options directives. The gauge option is what makes it a gauge graph, and the noo option suppresses one side of the graph (input or output). With the directives you can construct your own custom graph with correct units for uptime, and a scale that will make sense. You can control titles, legend values, etc.  
>>
>> Your first issue is how to convert 'Timeticks: (105630500) 12 days, 5:25:05.00' to a number. I would suggest graphing the hours of uptime. Even after a few years of uptime, the value itself will be less than 100,000 and probably graph well over time. 
>>
>> MRTG provides for pre-processing of SNMP values before they are passed to MRTG. I'm performing math before I use the voltage value. Since I'm pretty sure that the math is any valid perl statement, you might be able to get away with Perl. That being said, you may be best served by simply creating your own data collection plug-in, which is thankfully easier done than said. Straight from the book:
>>
>> Target[ezwf]: `/usr/local/bin/mrtg-scripts -a 1`
>>
>> All you need to is create a bash script that pipes your snmpwalk output into a awk, and then convert the returned value into the number of hours. Timeticks can be converted to hours: Hours = Timeticks / 100 / 60 / 60. 
>>
>> Something like:
>>
>> uptime=`snmpwalk -v1 -c public 10.0.0.1 SysUptime | awk -F'[()]' '{print $2}'`
>> let hours=uptime
>> let hours=$hours/100/60/60
>> echo $hours
>>
>> If you run that bash and pass it into MRTG, with directives to create a gauge type graph, you should get a fairly nifty uptime graph. With correct units for time as a bonus. 
>>
>>
>>
>> Sincerely, 
>>
>> Edwin A Epstein, III 
>> Rhinobee Internet Services 
>> 707.237.7504 ext 209 
>> 707.737.0288 Mobile
>>
>> ----- Original Message -----
>> From: "mrtg-request" <mrtg-request at lists.oetiker.ch>
>> To: "mrtg" <mrtg at lists.oetiker.ch>
>> Sent: Friday, September 28, 2018 3:00:02 AM
>> Subject: mrtg Digest, Vol 132, Issue 1
>>
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>> Today's Topics:
>>
>>    1. Graphing uptime (Daniel Beardsmore)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Fri, 28 Sep 2018 10:06:23 +0100
>> From: "Daniel Beardsmore" <resident at telcontar.net>
>> To: <mrtg at lists.oetiker.ch>
>> Subject: [mrtg] Graphing uptime
>> Message-ID: <041801d4570a$88f67650$9ae362f0$@telcontar.net>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> Hello
>>
>>  
>>
>> I can see that graphing uptime is possible, as you can see here:
>>
>>  
>>
>> http://www.hotelsvillegia.com/mrtg/uptime.html
>>
>>  
>>
>> The HTML pages report uptime in the format: "163 days, 21:07:10"
>>
>>  
>>
>> If I check manually, I get this:
>>
>>  
>>
>> snmpget -v2c -c somecommunity somehost 1.3.6.1.2.1.1.3.0
>>
>> DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (1415941565) 163 days,
>> 21:10:15.65
>>
>>  
>>
>> The format is almost the same, but the latter contains the full centisecond
>> accuracy. You do nonetheless get the raw number included.
>>
>>  
>>
>> Now, using this in MRTG yields:
>>
>>  
>>
>> 2018-09-27 19:56:04 -- 2018-09-27 19:51:33: WARNING: Expected a number but
>> got '163 days, 7:17:10'
>>
>>  
>>
>> Looking at the source code, I cannot determine quite how uptime is
>> processed. It seems odd that the format is almost the same (without the
>> centiseconds), which suggests (along with other code) that MRTG receives
>> pre-formatted output, and then has to scrape out the useful bits. (Which is
>> just plain horrible if this is true.)
>>
>>  
>>
>> Am I right in thinking that MRTG presently has no way to extract the raw
>> figure here? It seems that the SNMP library is formatting the data
>> prematurely and MRTG just works with that preformatted value as it suits its
>> own purposes, but that you cannot get the raw data out if you choose, for
>> example if you want to record uptime as a graph for checking for reboots.
>>
>>  
>>
>> In the example posted, I suspect that was bodged to get that to work.
>>
>>  
>>
>> Regards
>>
>>  
>>
>> Daniel. 
>>
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