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Go (golang) Bindings for rrdcached

This package implements Go (golang) bindings for the rrdcached daemon.

Install

go get github.com/dreadpirateshawn/rrdcached

Requirements

rrdcached was developed against RRDCacheD 1.5.0-rc2 and expects CREATE support. Technically the pre-1.5 methods work with older libraries -- UPDATE, FLUSH, etc -- but the test suite leverages CREATE, so it's easiest to use out-of-the-box with the newer library.

RRDTool / RRDCacheD can be found here: https://github.com/oetiker/rrdtool-1.x

Basic RRDCacheD test

Unit tests

go test -v ./...

The go-rrdcached test suite starts and stops rrdcached daemon instances of its own, so you don't need to leave rrdcached running during development.

Integration tests

rrdcached -p /tmp/go-rrdached-test.pid -B -b /tmp -l /tmp/go-rrdcached-test.sock -l 0.0.0.0:50081
go test -v ./... -tags=integration

Manual validation

Verify socket connection using nc:

$ echo "STATS" | sudo nc -U /tmp/go-rrdcached-test.sock
9 Statistics follow
QueueLength: 0
UpdatesReceived: 0
... etc ...

Verify TCP connection using telnet:

$ telnet 0.0.0.0 50081
Trying 0.0.0.0...
Connected to 0.0.0.0.
Escape character is '^]'.
STATS
9 Statistics follow
QueueLength: 0
UpdatesReceived: 0
... etc ...
^]
telnet> quit
Connection closed.

Btw: Telnet doesn't work for unix:socket.

Troubleshooting

If you encounter permission problems accessing the socket from your Go program, here's what I've done to work around this. (TODO: Shouldn't this library be usable without doing this?)

  • Change the default socket location. Add OPTS="-l unix:/socks/rrdcached.sock" to /etc/default/rrdcached
  • Start the rrdcached daemon. sudo /etc/init.d/rrdcached start
  • Ensure permissions. sudo chmod -R 777 /socks/
  • View syslogs. tail /var/log/syslog

Open Questions

  • RRD requires timestamp to increase by at least one second for each update value... does this library do enough to bubble up this error when it happens?

  • What if filenames with spaces are used?

  • What if Update is called with empty values? no-op or panic?

  • Tests cover one RRD with multiple dimensions, should they also cover multiple RRDs with one dimension each? https://kb.op5.com/display/HOWTOs/Use+RRD+in+MULTIPLE+mode+for+separate+check+commands