This is a simple docker solution to experiment with the excellent RRDtool.
This docker image will start the rrdcached daemon and listen on port 5000.
$ docker build -t rrd:latest .
Once built, you can also choose three directories to persist your data.
For example, if you would like to persist in /tmp, you can try somethgin like the following:
$ mkdir /tmp/rrd_data /tmp/rrd_tmp /tmp/rrd_journal
Run the following:
$ docker run -p 127.0.0.1:5000:5000 -v /tmp/rrd_data:/rrd_data -v \
/tmp/rrd_tmp:/rrd_tmp -v /tmp/rrd_journal:/rrd_journal \
-d -t rrd:latest
You should see something like this with the docker ps command:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ed5124bca087 rrd:latest "rrdcached -l 0.0.0.0" 3 seconds ago Up 2 seconds 127.0.0.1:5000->5000/tcp jovial_mahavira
To test the service, you can use a normal Telnet client and communicate to the server using the normal RRD text protocol (see documentation):
$ telnet 127.0.0.1 5000
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
CREATE datafile_001.rrd -s 300 -O DS:temp:GAUGE:600:-273:5000 RRA:AVERAGE:0.5:1:1200 RRA:MIN:0.5:12:2400 RRA:MAX:0.5:12:2400 RRA:AVERAGE:0.5:12:2400
0 RRD created OK
UPDATE datafile_001.rrd 1483017326:14
0 errors, enqueued 1 value(s).
STATS
9 Statistics follow
QueueLength: 0
UpdatesReceived: 1
FlushesReceived: 0
UpdatesWritten: 0
DataSetsWritten: 0
TreeNodesNumber: 1
TreeDepth: 1
JournalBytes: 98
JournalRotate: 0
QUIT
Connection closed by foreign host.
And there you have it.
To start the image with an interactive shell:
$ docker run -p 127.0.0.1:5000:5000 -v /tmp/rrd_data:/rrd_data -v \
/tmp/rrd_tmp:/rrd_tmp -v /tmp/rrd_journal:/rrd_journal \
-i -t rrd:latest /bin/bash -i
You can then start the rrdcached daemon manually with:
$ rrdcached -l 0.0.0.0:5000 -z 2 -f 3600 -p /rrd_tmp/rrdcached.pid -t 8 -j /rrd_journal -g -b /rrd_data
The following examples illustrate how to create an RRD database for 2 random number generators that will store a value every 20 seconds while keeping the data for 1 year. The database is less then 50MiB in size, which is actually impressive taken into account the fast number of data that will be stored.
The following is an example CREATE command - first the CLI method as an example:
$ rrdtool create random_number.rrd --step 30 DS:generator1:GAUGE:60:0:100 DS:generator2:GAUGE:60:0:100 RRA:MIN:0.5:1:1051200 RRA:MAX:0.5:1:1051200 RRA:AVERAGE:0.5:1:1051200
And now the protocol version (enter this into your Telnet session):
CREATE random_number.rrd -s 30 -O DS:generator1:GAUGE:60:0:100 DS:generator2:GAUGE:60:0:100 RRA:MIN:0.5:1:1051200 RRA:MAX:0.5:1:1051200 RRA:AVERAGE:0.5:1:1051200
Hint: To help you create a RRD database, use a wizard like this one...
These scripts or commands should be run from your main system (not the Docker service).
You can use the following bash one liner to add data every 20 seconds in an infinite loop:
$ while true; do (sleep 1; echo "UPDATE random_number.rrd "`date +%s`":"`echo $((0 + RANDOM % 100))`":"`echo $((0 + RANDOM % 100))`; sleep 1 ; echo QUIT) | telnet 127.0.0.1 5000; sleep 20; done
This take some time, but you can also generate a batch of values quickly using the script in the examples directory.
At the moment, the graph cannot be generated through the TCP protocol, but if you enter the interactive console, you can generate a graph with something like the following:
$ rrdtool graph /rrd_tmp/random_number.png -s 1483041600 -e 1483084800 -S 600 -t 'Random Number Generators Data from 2016-12-29 22:00:00 to 2016-12-30 10:00:00' -w 800 -h 600 -a PNG DEF:g1=/rrd_data/random_number.rrd:generator1:AVERAGE DEF:g2=/rrd_data/random_number.rrd:generator2:AVERAGE LINE2:g1#000000:Generator_1 AREA:g2#ff000080:Generator_2
The values for -s and -e is the UNIX timestamp for the start and stop time. You can calculate it easily in Bash with something like the following:
$ date -d '2016-12-30 10:00:00' +%s
1483084800