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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>/<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'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'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
${SCRIPTS}/interface.sh host2.domain.tld 11
</pre>
<p>The resulting graphs:</p>
<p><img src="https://ops.high5.nl/obsda.ms/s1.obsda.ms-cpu.png" alt="" />
<img src="https://ops.high5.nl/obsda.ms/s1.obsda.ms-12.png" alt="" /></p>
<p>To serve the graphs we use <a href="http://man.openbsd.org/httpd.8">httpd(8)</a> with the following config:
<pre>
server "default" {
listen on * port 80
location "/.well-known/acme-challenge/*" {
root "/acme"
request strip 2
}
location * {
block return 302 "https://$HTTP<em>HOST$REQUEST</em>URI"
}
}</p>
<p>server "default" {
listen on * tls port 443
tls {
certificate "/etc/ssl/default-fullchain.pem"
key "/etc/ssl/private/default.key"
}
location "/.well-known/acme-challenge/*" {
root "/acme"
request strip 2
}
root "/htdocs"
}
</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">
© 2018–2020 OpenBSD Amsterdam is a project of <a href="https://high5.nl/">High5!</a>
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