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<h1 id="RRDtool%20looks%20nicer...">RRDtool looks nicer...</h1>

<p class="f7">March 14, 2019</p>

<p><a href="https://openbsd.amsterdam/">OpenBSD Amsterdam</a> was in search of a lightweight toolset to keep track of resource usage, at a minimum the CPU load generated by the <a href="https://man.openbsd.org/vmm.4">vmm(4)</a>&#47;<a href="https://man.openbsd.org/vmd.8">vmd(8)</a> hosts and the traffic from and to the hosts. A couple of weeks ago we ended up with a workable <a href="https://openbsd.amsterdam/blog/using-mrtg-again.html">MRTG Setup</a>. While it worked, it didn&#39;t look very pretty.</p>

<p>In a moment of clarity, we thought about using <a href="https://oss.oetiker.ch/rrdtool/">RRDtool</a>. Heck, why shouldn&#39;t we give it a try? From the previous tooling, we already had some required building blocks in place to make <a href="https://oss.oetiker.ch/mrtg/">MRTG</a> understand the CPU Cores and uptime from <a href="https://openbsd.org/">OpenBSD</a>.</p>

<p>Before we start:</p>

<pre>
# <b>pkg_add rrdtool</b>
#
</pre>

<p>We decided to split the collection of the different OIDs (SNMP Object Identifiers) into three different scripts, which <a href="https://man.openbsd.org/cron.1">cron(1)</a> calls, from a wrapper script.</p>

<ul>
<li>uptime.sh</li>
<li>cpu_load.sh</li>
<li>interface.sh</li>
</ul>

<h3 id="uptime.sh">uptime.sh</h3>

<pre>
#!/bin/sh
test -n "$1" || exit 1
HOST="$1"
COMMUNITY="public"
UPTIMEINFO="/tmp/${HOST}-uptime.txt"
TICKS=$(snmpctl snmp get ${HOST} community ${COMMUNITY} oid hrSystemUptime.0 | cut -d= -f2)
DAYS=$(echo "${TICKS}/8640000" | bc -l)
HOURS=$(echo "0.${DAYS##*.} * 24" | bc -l)
MINUTES=$(echo "0.${HOURS##*.} * 60" | bc -l)
SECS=$(echo "0.${MINUTES##*.} * 60" | bc -l)
test -n "$DAYS" && printf '%s days, ' "${DAYS%.*}" > ${UPTIMEINFO}
printf '%02d\\:%02d\\:%02d\n' "${HOURS%.*}" "${MINUTES%.*}" "${SECS%.*}" >> ${UPTIMEINFO}
</pre>

<p>This is a seperate script, due to the uptime usage of both hosts in both graphs. </p>

<p>The origins for this script can be found detailled in our <a href="https://openbsd.amsterdam/blog/using-mrtg-again.html">MRTG Setup</a>.</p>

<h3 id="cpu_load.sh">cpu_load.sh</h3>

<pre>
test -n "$1" || exit 1
HOST="$1"
COMMUNITY="public"
RRDFILES="/var/rrdtool"
IMAGES="/var/www/htdocs"
WATERMARK="OpenBSD Amsterdam - https://obsda.ms"
RRDTOOL="/usr/local/bin/rrdtool"
CPUINFO="/tmp/${HOST}-cpu.txt"
UPTIME=$(cat /tmp/${HOST}-uptime.txt)
NOW=$(date "+%Y-%m-%d %H:%M:%S %Z" | sed 's/:/\\:/g')

if ! test -f "${RRDFILES}/${HOST}-cpu.rrd"
then
echo "Creating ${RRDFILES}/${HOST}-cpu.rrd"
${RRDTOOL} create ${RRDFILES}/${HOST}-cpu.rrd \
        --step 300 \
        DS:ds0:GAUGE:600:U:U \
        RRA:MAX:0.5:1:20000
fi

snmpctl snmp walk ${HOST} community ${COMMUNITY} oid hrProcessorLoad | cut -d= -f2 > ${CPUINFO}
CORES=$(grep -cv "^0$" ${CPUINFO})
CPU_LOAD_SUM=$(awk '{sum += $1} END {print sum}' ${CPUINFO})
CPU_LOAD=$(echo "scale=2; ${CPU_LOAD_SUM}/${CORES}" | bc -l)

${RRDTOOL} update ${RRDFILES}/${HOST}-cpu.rrd N:${CPU_LOAD}

${RRDTOOL} graph ${IMAGES}/${HOST}-cpu.png \
        --start -43200 \
        --title "${HOST} - CPU" \
        --vertical-label "% CPU Used" \
        --watermark "${WATERMARK}" \
        DEF:CPU=${RRDFILES}/${HOST}-cpu.rrd:ds0:AVERAGE \
        AREA:CPU#FFCC00 \
        LINE2:CPU#CC0033:"CPU" \
        GPRINT:CPU:MAX:"Max\:%2.2lf %s" \
        GPRINT:CPU:AVERAGE:"Average\:%2.2lf %s" \
        GPRINT:CPU:LAST:" Current\:%2.2lf %s\n" \
        COMMENT:"\\n" \
        COMMENT:"  SUM CPU Load / Active Cores = % CPU Used\n" \
        COMMENT:"  Up for ${UPTIME} at ${NOW}"
</pre>

<p>On the first run, <a href="https://oss.oetiker.ch/rrdtool/">RRDtool</a> will create the .rrd file. On every subsequent run, it will update the file with the collected values and update the graph.</p>

<p>The origins for this script can be found detailled in our <a href="https://openbsd.amsterdam/blog/using-mrtg-again.html">MRTG Setup</a>.</p>

<h3 id="interface.sh">interface.sh</h3>

<pre>
test -n "$1" || exit 1                                                                             
test -n "$2" || exit 1                                                                             
HOST="$1"                                                                                          
INTERFACE="$2"                                                                                     
COMMUNITY="public"                                                                                 
RRDFILES="/var/rrdtool"
IMAGES="/var/www/htdocs"
WATERMARK="OpenBSD Amsterdam - https://obsda.ms"
RRDTOOL="/usr/local/bin/rrdtool"
UPTIME=$(cat /tmp/${HOST}-uptime.txt)
NOW=$(date "+%Y-%m-%d %H:%M:%S %Z" | sed 's/:/\\:/g')                                              

if ! test -f "${RRDFILES}/${HOST}-${INTERFACE}.rrd"                                                
then
echo "Creating ${RRDFILES}/${HOST}-${INTERFACE}.rrd"                                               
${RRDTOOL} create ${RRDFILES}/${HOST}-${INTERFACE}.rrd \                                           
        --step 300 \
        DS:ds0:COUNTER:600:0:1250000000 \
        DS:ds1:COUNTER:600:0:1250000000  \
        RRA:AVERAGE:0.5:1:600 \
        RRA:AVERAGE:0.5:6:700 \
        RRA:AVERAGE:0.5:24:775 \
        RRA:AVERAGE:0.5:288:797 \
        RRA:MAX:0.5:1:600 \
        RRA:MAX:0.5:6:700 \
        RRA:MAX:0.5:24:775 \
        RRA:MAX:0.5:288:797
fi

IN=$(snmpctl snmp get ${HOST} community ${COMMUNITY} oid ifInOctets.${INTERFACE} | cut -d= -f2)    
OUT=$(snmpctl snmp get ${HOST} community ${COMMUNITY} oid ifOutOctets.${INTERFACE} | cut -d= -f2)  
DESCR=$(snmpctl snmp get ${HOST} community ${COMMUNITY} oid ifDescr.${INTERFACE} | cut -d= -f2 | tr
-d '"')

${RRDTOOL} update ${RRDFILES}/${HOST}-${INTERFACE}.rrd N:${IN}:${OUT}                              

${RRDTOOL} graph ${IMAGES}/${HOST}-${INTERFACE}.png \                                              
        --start -43200 \
        --title "${HOST} - ${DESCR}" \
        --vertical-label "Bits per Second" \
        --watermark "${WATERMARK}" \
        DEF:IN=${RRDFILES}/${HOST}-${INTERFACE}.rrd:ds0:AVERAGE \                                  
        DEF:OUT=${RRDFILES}/${HOST}-${INTERFACE}.rrd:ds1:AVERAGE \                                 
        CDEF:IN_CDEF="IN,8,*" \
        CDEF:OUT_CDEF="OUT,8,*" \
        AREA:IN_CDEF#00FF00:"In " \
        GPRINT:IN_CDEF:MAX:"Max\:%5.2lf %s" \
        GPRINT:IN_CDEF:AVERAGE:"Average\:%5.2lf %s" \                                              
        GPRINT:IN_CDEF:LAST:" Current\:%5.2lf %s\n" \                                              
        LINE2:OUT_CDEF#0000FF:"Out" \
        GPRINT:OUT_CDEF:MAX:"Max\:%5.2lf %s" \
        GPRINT:OUT_CDEF:AVERAGE:"Average\:%5.2lf %s" \                                             
        GPRINT:OUT_CDEF:LAST:" Current\:%5.2lf %s\n" \                                             
        COMMENT:"\\n" \
        COMMENT:"  Up for ${UPTIME} at ${NOW}"
</pre>

<p>To pinpoint the network interface you want to measure the bandwith for, this command prints the available interfaces:</p>

<pre>
snmpctl snmp walk [host] community [community] oid ifDescr
</pre>

<p>This will output a list like:</p>

<pre>
ifDescr.1="em0"
ifDescr.2="em1"
ifDescr.3="enc0"
ifDescr.4="lo0"
ifDescr.5="bridge880"
ifDescr.6="vlan880"
ifDescr.13="pflog0"
ifDescr.669="tap0"
ifDescr.670="tap1"
</pre>

<p>The number behind <code>ifDescr</code> is the one that you need to feed to <strong>interface.sh</strong>, for example:</p>

<pre>
# interface.sh 5
</pre>

<p>Finally the <strong>wrapper.sh</strong> script calls all the aforementioned scripts:</p>

<pre>
#!/bin/sh
SCRIPTS="/var/rrdtool"
for i in $(jot 2 1); do ${SCRIPTS}/uptime.sh host${i}.domain.tld; done
for i in $(jot 2 1); do ${SCRIPTS}/cpu_load.sh host${i}.domain.tld; done
${SCRIPTS}/interface.sh host1.domain.tld 12
${SCRIPTS}/interface.sh host2.domain.tld 11
</pre>

<p>The resulting graphs:</p>

<p><img src="https://ops.high5.nl/obsda.ms/s1.obsda.ms-cpu.png" alt="" />
<img src="https://ops.high5.nl/obsda.ms/s1.obsda.ms-12.png" alt="" /></p>

<p>To serve the graphs we use <a href="http://man.openbsd.org/httpd.8">httpd(8)</a> with the following config:
<pre>
server &#34;default&#34; {
        listen on * port 80
        location &#34;&#47;.well-known&#47;acme-challenge&#47;*&#34; {
                root &#34;&#47;acme&#34;
                request strip 2
        }
        location * {
                block return 302 &#34;https:&#47;&#47;$HTTP<em>HOST$REQUEST</em>URI&#34;
        }
}</p>

<p>server &#34;default&#34; {
        listen on * tls port 443
        tls {
                certificate &#34;&#47;etc&#47;ssl&#47;default-fullchain.pem&#34;
                key &#34;&#47;etc&#47;ssl&#47;private&#47;default.key&#34;
        }
        location &#34;&#47;.well-known&#47;acme-challenge&#47;*&#34; {
                root &#34;&#47;acme&#34;
                request strip 2
        }
        root &#34;&#47;htdocs&#34;
}
</pre>
All the scripts can be found in our <a href="https://git.high5.nl/rrdtool">Git Repository</a>.</p>

<p>You can follow us on <a href="https://twitter.com/@OpenBSDAms">Twitter</a> and <a href="https://bsd.network/@OpenBSDAms">Mastodon</a>.</p>
<p class="footer f7 mt4">
&copy; 2018&ndash;2020 OpenBSD Amsterdam is a project of <a href="https://high5.nl/">High5!</a>
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