opentelemetry-exporter-otlp-metrics

The opentelemetry-exporter-otlp-metrics gem provides an OTLP metrics exporter for OpenTelemetry for Ruby. Using opentelemetry-exporter-otlp-metrics, an application can configure OpenTelemetry to export collected metrics data to the OpenTelemetry Collector.

What is OpenTelemetry?

OpenTelemetry is an open source observability framework, providing a general-purpose API, SDK, and related tools required for the instrumentation of cloud-native software, frameworks, and libraries.

OpenTelemetry provides a single set of APIs, libraries, agents, and collector services to capture distributed traces and metrics from your application. You can analyze them using Prometheus, Jaeger, and other observability tools.

How does this gem fit in?

The opentelemetry-exporter-otlp-metrics gem is a plugin that provides OTLP export. To export to the OpenTelemetry Collector, an application can include this gem along with opentelemetry-sdk, and configure the SDK to use the provided OTLP exporter with a metric reader.

Generally, libraries that produce telemetry data should avoid depending directly on specific exporter, deferring that choice to the application developer.

Supported protocol version

This gem supports the v0.20.0 release of OTLP.

Prerequisite

The exporter-oltp-metrics depends on two gems that have not been officially released: opentelemetry-metrics-sdk and opentelemetry-metrics-api.

Within the .gemspec file, these gems are not listed as dependencies. However, for users who need utilize this metrics exporter, they must first install and load these two gems before they can use the exporter.

To facilitate this, there are couple recommended approaches:

1. Download the source code

Download the opentelemetry-ruby.
Navigate to subfolder, then build the metrics_sdk and metrics_api.
Execute gem build *.gemspec.
Lastly, install the built gem into the system.

2. Using `path:` option in Gemfile with downloaded source code

git clone opentelemetry-ruby first, then use Gemfile

# Gemfile
source 'https://rubygems.org'
gem 'opentelemetry-metrics-api', path: "opentelemetry-ruby/metrics_api"
gem 'opentelemetry-metrics-sdk', path: "opentelemetry-ruby/metrics_sdk"

3. Using `git:` option in Gemfile

# Gemfile
source 'https://rubygems.org'
gem 'opentelemetry-metrics-api', git: "https://github.com/open-telemetry/opentelemetry-ruby", glob: 'metrics_api/*.gemspec'
gem 'opentelemetry-metrics-sdk', git: "https://github.com/open-telemetry/opentelemetry-ruby", glob: 'metrics_sdk/*.gemspec'

How do I get started?

Install the gem using:


gem install opentelemetry-sdk
gem install opentelemetry-metrics-sdk
gem install opentelemetry-exporter-otlp-metrics

Or, if you use bundler, include opentelemetry-sdk, opentelemetry-metrics-sdk, and opentelemetry-exporter-otlp-metrics in your Gemfile.

Then, configure the SDK to use the OTLP metrics exporter

require 'opentelemetry/sdk'
require 'opentelemetry-metrics-sdk'
require 'opentelemetry/exporter/otlp_metrics'

OpenTelemetry::SDK.configure

# To start a trace you need to get a Tracer from the TracerProvider

otlp_metric_exporter = OpenTelemetry::Exporter::OTLP::Metrics::MetricsExporter.new

OpenTelemetry.meter_provider.add_metric_reader(otlp_metric_exporter)

meter = OpenTelemetry.meter_provider.meter("SAMPLE_METER_NAME")

histogram = meter.create_histogram('histogram', unit: 'smidgen', description: 'desscription')

histogram.record(123, attributes: {'foo' => 'bar'})

OpenTelemetry.meter_provider.metric_readers.each(&:pull)
OpenTelemetry.meter_provider.shutdown

For additional examples, see the examples on github.

How can I configure the OTLP metrics exporter?

The collector exporter can be configured explicitly in code, or via environment variables as shown above. The configuration parameters, environment variables, and defaults are shown below.

ssl_verify_mode: parameter values should be flags for server certificate verification: OpenSSL::SSL:VERIFY_PEER and OpenSSL::SSL:VERIFY_NONE are acceptable. These values can also be set using the appropriately named environment variables as shown where VERIFY_PEER will take precedence over VERIFY_NONE. Please see the Net::HTTP docs for more information about these flags.

How can I get involved?

The opentelemetry-exporter-otlp-metrics gem source is on github, along with related gems including opentelemetry-metrics-sdk.

The OpenTelemetry Ruby gems are maintained by the OpenTelemetry-Ruby special interest group (SIG). You can get involved by joining us in GitHub Discussions or attending our weekly meeting. See the meeting calendar for dates and times. For more information on this and other language SIGs, see the OpenTelemetry community page.

License

The opentelemetry-exporter-otlp-metrics gem is distributed under the Apache 2.0 license. See LICENSE for more information.

Working with Proto Definitions

The OTel community maintains a repository with protobuf definitions that language and collector implementers use to generate code.

Maintainers are expected to keep up to date with the latest version of protos. This guide will provide you with step-by-step instructions on updating the OTLP Exporter gem with the latest definitions.

System Requirements

2.41+[https://git-scm.com/book/en/v2/Getting-Started-Installing-Git]
22.5[https://github.com/protocolbuffers/protobuf/releases/tag/v22.5]
Ruby 3+

:warning: protoc 23.x changes the Ruby code generator to emit a serialized proto instead of a DSL. protobuf.dev/news/2023-04-20/. Please ensure you use protoc version 22.x in order to ensure we remain compatible with versions of protobuf prior to google-protobuf gem 3.18.

Upgrade Proto Definitions

Update the target otel-proto version in the Rakefile that matches a release tag in the proto repo, e.g.

# Rakefile

  # https://github.com/open-telemetry/opentelemetry-proto/tree/v0.20.0
  PROTO_VERSION = `v0.20.0`

Generate the Ruby source files using rake:


$> bundle exec rake protobuf:generate

Run tests and fix any errors:


$> bundle exec rake test

Commit the changes and open a PR!