Introduction¶ ↑

rrd-ffi is a gem for using rrd actions in your ruby code.

You may use it in the raw format, as many rrd libs in languages like perl or python, or you can use it through the dsl we provide.

rrd-ffi uses ffi to wrap the librrd C bindings, not system calls.

IMPORTANT: You need librrd installed (version 1.3.1 or above, version 1.4.2 RECOMMENDED) in your system for this gem to work

Basics¶ ↑

Here’s what you need to know before starting.

Installation¶ ↑

Notes¶ ↑

To install rrd-ffi, you will need to have librrd in your system.

Then, run sudo gem install rrd-ffi

If you are using Mac Ports you will have problems, so add the following to your .profile|.bashrc|.bash_profile file:

export RRD_LIB=/opt/local/lib/librrd.dylib

or

export LD_LIBRARY_PATH=/opt/local/lib

If you are not using MAC OS and still having problems, export the RRD_PATH variable with the path to your librrd file.

Installing librrd¶ ↑

Debian/Ubuntu: apt-get install librrd-dev

Fedora/Red Hat: yum install rrdtool-devel

Mac: port install rrdtool

From source:

cd rrdtool-${rrdtool_version}
./configure --disable-ruby --prefix=/usr/local
make
make install

Example Usage¶ ↑

require "rrd"
rrd = RRD::Base.new("myrrd.rrd")
# Restoring a rrd file from xml
# Notice that all '-' on flags become '_' like --force-overwrite => :force_overwrite
rrd.restore("myrrd.xml", :force_overwrite => true)

# Fetching data from rrd
rrd.fetch(:average).each {|line| puts line.inspect}

# Collecting information from rrd
puts rrd.info.to_yaml

# Updating rrd (this rrd example has 3 datasources)
rrd.update Time.now, 500, nil, 30

# Looking for the first and last entered dates
puts rrd.starts_at
puts rrd.ends_at

# Growing or Shrinking a rrd_file (create a resize.rrd file)
# You need to know the RRA number (starting from 0)
rrd.resize(0, :grow => 10.days)
rrd.resize(0, :shrink => 10.days)

# Error handling
rrd.fetch(:unknown_function) # should return false
puts rrd.error

# For raising exceptions in methods, use the '!' at its end
rrd.fetch!(:unknown_function) # raises an error

DSLs¶ ↑

# Creating a new rrd
rrd = RRD::Base.new("myrrd.rrd")
rrd.create :start => Time.now - 10.seconds, :step => 5.minutes do
  datasource "memory", :type => :gauge, :heartbeat => 10.minutes, :min => 0, :max => :unlimited
  archive :average, :every => 10.minutes, :during => 1.year
end

# Generating a graph with memory and cpu usage from myrrd.rrd file
RRD.graph "graph.png", :title => "Test", :width => 800, :height => 250, :color => ["FONT#000000", "BACK#FFFFFF"] do
  area "myrrd.rrd", :cpu0 => :average, :color => "#00FF00", :label => "CPU 0"
  line "myrrd.rrd", :cpu0 => :average, :color => "#007f3f"
  line "myrrd.rrd", :memory => :average, :color => "#0000FF", :label => "Memory"
end

# Generating a graph or raising an exception if something bad happens
RRD.graph! "graph.png", :title => "Test", :width => 800, :height => 250, :color => ["FONT#000000", "BACK#FFFFFF"] do
  area "myrrd.rrd", :cpu0 => :average, :color => "#00FF00", :label => "CPU 0"
  line "myrrd.rrd", :cpu0 => :average, :color => "#007f3f"
  line "myrrd.rrd", :memory => :average, :color => "#0000FF", :label => "Memory"
end

# Generating a more complex graph using advanced DSL
RRD.graph IMG_FILE, :title => "Test", :width => 800, :height => 250, :start => Time.now - 1.day, :end => Time.now do
  for_rrd_data "cpu0", :cpu0 => :average, :from => RRD_FILE
  for_rrd_data "mem", :memory => :average, :from => RRD_FILE
  using_calculated_data "half_mem", :calc => "mem,2,/"
  using_value "mem_avg", :calc => "mem,AVERAGE"
  draw_line :data => "mem", :color => "#0000FF", :label => "Memory", :width => 1
  draw_area :data => "cpu0", :color => "#00FF00", :label => "CPU 0"
  print_comment "Information - "
  print_value "mem_avg", :format => "%6.2lf %SB"
end

# Generating a graph using shift
RRD.graph IMG_FILE, :title => "Test", :width => 800, :height => 250, :start => Time.now - 1.day, :end => Time.now do
  for_rrd_data "mem", :memory => :average, :from => RRD_FILE
  for_rrd_data "mem_yesterday", :memory => :average, :from => RRD_FILE, :start => Time.now - 2.day
  draw_line :data => "mem", :color => "#0000FF", :label => "Memory", :width => 1
  shift :mem_yesterday => 1.day
  draw_line :data => "mem_yesterday", :color => "#0000FF", :label => "Yesterday memory", :width => 1
end

Raw API Usage¶ ↑

Normal methods return false on error, or the expected result otherwise.

# Creating a rrd file

RRD::Wrapper.create "myrrd.rrd", "--step", "300", "DS:ifOutOctets:COUNTER:1800:0:4294967295", "RRA:AVERAGE:0.5:1:2016"

# Fetching average data

RRD::Wrapper.fetch "myrrd.rrd", "AVERAGE"

# Looking for the first entered dates

RRD::Wrapper.first "myrrd.rrd"

# Creating a graph

RRD::Wrapper.graph("graph.png", "DEF:data=myrrd.rrd:ifOutOctets:AVERAGE", "LINE1:data#0000FF:Output bytes")

# Getting info on a rrd file

RRD::Wrapper.info("myrrd.rrd")

# Looking for the last entered dates

RRD::Wrapper.last “myrrd.rrd”

# Getting last data inserted on a rrd RRD::Wrapper.last_update “myrrd.rrd”

# Resizing a rrd file RRA

RRD::Wrapper.resize "myrrd.rrd", "0", "GROW", "10"

# Restoring a rrd file from xml
RRD::Wrapper.restore "myrrd.xml", "myrrd.rrd"

# Tuning a rrd file

RRD::Wrapper.tune "myrrd.rrd", "--minimum", "memory:5"

# Updating rrd with a new value
RRD::Wrapper.update "myrrd.rrd", "N:500000000"

# Getting the error happened
puts RRD::Wrapper.error

Bang methods raise exception on error.

# Throwing the error if happens
RRD::Wrapper.fetch! "myrrd.rrd", "WRONG FUNCTION"