CMetrics Ruby

A Ruby binding for cmetrics.

Prerequisites

• Ruby 2.4 or later with its headers
• CMake 3.13 or later due to different directory TARGETS for bundled cmetrics installation
• gcc or clang or some equivalents toolchain

Installation

Add this line to your application's Gemfile:

gem 'cmetrics'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install cmetrics

Usage

Counter

CMetrics::Counter is a cumulative metric that can only increase monotonically and reset to zero at restart. This class should be used for counting the total amount of record size or something like monotonic increasing values.

ref: Metric Types -- Counter | Prometheus documentation

require 'cmetrics'

@counter = CMetrics::Counter.new
@counter.create("kubernetes", "network", "load", "Network load", ["hostname", "app"])

@counter.val #=> nil
@counter.inc #=> true

@counter.val #=> 1.0
@counter.add 2.0 #=> true
@counter.val #=> 3.0

# Multiple labels
@counter.inc(["localhost", "cmetrics"]) #=> true
@counter.val(["localhost", "cmetrics"]) #=> 1.0

@counter.add(10.55, ["localhost", "test"]) #=> true
@counter.val(["localhost", "test"]) #=> 10.55

#CMetrics::Counter can set greater value than stored.
@counter.set(12.15, ["localhost", "test"]) #=> true
#CMetrics::Counter cannot set smaller value than stored.
@counter.set(1, ["localhost", "test"]) #=> false

Gauge

CMetrics::Gauge is a metric that can represent arbitrary values and arbitrarily go up and down. This class should be used for counting to be going up and down values such as CPU and memory usages, queued buffer size or something can go up, down and to be zero.

ref: Metric Types -- Gauge | Prometheus documentation

require 'cmetrics'

@gauge = CMetrics::Gauge.new
@gauge.create("kubernetes", "network", "load", "Network load", ["hostname", "app"])

@gauge.val #=> nil
@gauge.inc #=> true

@gauge.val #=> 1.0
@gauge.add 2.0 #=> true
@gauge.val #=> 3.0

# Multiple labels
@gauge.inc(["localhost", "cmetrics"]) #=> true
@gauge.val(["localhost", "cmetrics"]) #=> 1.0

@gauge.add(10, ["localhost", "test"]) #=> true
@gauge.val(["localhost", "test"]) #=> 10

@gauge.sub(2.5, ["localhost", "test"]) #=> true
@gauge.val(["localhost", "test"]) #=> 7.5

Untyped

CMetrics::Untyped is a metric that can only set a value via #set and reset to zero at restart. This class should be used for storing the increasing but discontinuous values.

require 'cmetrics'

@untyped = CMetrics::Untyped.new
@untyped.create("kubernetes", "network", "load", "Network load", ["hostname", "app"])

@untyped.val #=> nil

@untyped.set 3.0 #=> true
@untyped.val #=> 3.0

# Multiple labels
@untyped.set(1.0, ["localhost", "cmetrics"]) #=> true
@untyped.val(["localhost", "cmetrics"]) #=> 1.0

@untyped.set(10.55, ["localhost", "test"]) #=> true
@untyped.val(["localhost", "test"]) #=> 10.55

#CMetrics::Untyped can set greater value than stored.
@untyped.set(12.15, ["localhost", "test"]) #=> true
#CMetrics::Untyped cannot set smaller value than stored.
@untyped.set(1, ["localhost", "test"]) #=> false

Serde

CMetrics::Serde is for a decoding (and encoding to some format stuffs) from msgpacked buffers that are created by CMetrics::Counter#to_msgpack or CMetrics::Gauge#to_msgpack.

For Counter class instance(s)

require 'cmetrics'

@counter = CMetrics::Counter.new
@counter.create("kubernetes", "network", "load", "Network load", ["hostname", "app"])
@counter.inc
@counter.inc(["calyptia.com", "cmetrics"])
@counter.inc(["calyptia.com", "cmetrics"])
@buffer = @counter.to_msgpack
@serde = CMetrics::Serde.new

@serde.from_msgpack(@buffer)
puts @serde #=> Decoded object is shown with text

For Gauge class instance(s)

require 'cmetrics'

@gauge = CMetrics::Gauge.new
@gauge.create("kubernetes", "network", "load", "Network load", ["hostname", "app"])
@gauge.inc
@gauge.inc(["calyptia.com", "cmetrics"])
@gauge.inc(["calyptia.com", "cmetrics"])
@buffer = @gauge.to_msgpack
@serde = CMetrics::Serde.new

@serde.from_msgpack(@buffer)
puts @serde #=> Decoded object is shown with text

For wired buffer (multiple concatenated instances context)

require 'cmetrics'

@gauge = CMetrics::Gauge.new
@gauge.create("kubernetes", "network", "load", "Network load", ["hostname", "app"])
@gauge.set 2.0
@gauge.inc(["localhost", "cmetrics"])
@gauge.add(10, ["localhost", "test"])
@counter = CMetrics::Counter.new
@counter.create("kubernetes", "network", "load", "Network load", ["hostname", "app"])
@counter.inc
@counter.inc(["localhost", "cmetrics"])
@counter.add(10.55, ["localhost", "test"])
@counter2 = CMetrics::Counter.new
@counter2.create("cmt", "labels", "test", "Static labels test", ["host", "app"])
@counter2.inc
@counter2.inc(["calyptia.com", "cmetrics"])
@counter2.inc(["calyptia.com", "cmetrics"])
@counter2.add_label("dev", "Calyptia")
@counter2.add_label("lang", "C")
@wired_buffer = @gauge.to_msgpack + @counter.to_msgpack + @counter2.to_msgpack
@serde = CMetrics::Serde.new

puts "-----Decode with procedural style-----"
# Decode for the context 1
@serde.from_msgpack(@wired_buffer)
puts @serde.to_prometheus
# Decode for the context 2
@serde.from_msgpack(@wired_buffer)
puts @serde.to_prometheus
# Decode for the context 3
@serde.from_msgpack(@wired_buffer)
puts @serde.to_prometheus

puts "-----Decode with streaming style-----"
# Or, use streaming style API
@serde.feed_each(@wired_buffer) do |serde|
  puts serde.to_prometheus
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test-unit to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/calyptia/cmetrics-ruby.