otel-arrow

README

OTel Arrow Protocol

Repository under maintenance.

This repository recently migrated from the github.com/f5/otel-arrow-adapter, and we are preparing it for a beta release. While the repository is still in transition, the primary OpenTelemetry Collector components are housed here:

• OTel Arrow Receiver
• OTel Arrow Exporter (TODO)

Reference implementation.

This package is a reference implementation of the OTel Arrow protocol specified in this OTEP. All OTLP entities are covered (metrics, logs, and traces) as well as all sub-elements such as events, links, gauge, sum, summary, histograms, ... The overall goal is to optimize the compression ratio for telemetry data transmission as well as the end-to-end performance between telemetry data producers and receivers.

This package is still experimental and subject to change. It is currently used by an experimental OTLP/Arrow gRPC exporter and receiver.

Important links:

• OTEP - protocol specification.
• Donation - approved by the Technical Committee (repo not yet transferred in OTel org).
• Arrow Data Model - Mapping OTLP entities to Arrow Schemas.
• Benchmark results - Based on synthetic and production data.
• Validation process - Encoding/Decoding validation process.
• Articles describing some of the Arrow techniques used behind the scenes to optimize compression ratio and memory usage:
  • Data types, encoding, hierarchical data, denormalization
  • Adaptive Schemas and Sorting to Optimize Arrow Usage

Benchmark summary

The following chart shows the compressed message size (in bytes) as a function of the batch size for metrics (univariate), logs, and traces. The bottom of the chart shows the reduction factor for both the standard OTLP protocol (with ZSTD compression) and the OTel Arrow protocol (ZSTD) in comparison with an uncompressed OTLP protocol.

The next chart follows the same logic but shows the results for multivariate metrics (see left column).

For more details, see the following benchmark results page.

Phase 1 (current implementation)

This first step is intended to address the specific use cases of traffic reduction. Based on community feedback, many companies want to reduce the cost of transferring telemetry data over the Internet. By adding a collector that acts as a point of integration and traffic conversion at the edge of a client environment, we can take advantage of the columnar format to eliminate redundant data and optimize the compression rate. This is illustrated in the following diagram.

Note 1: A fallback mechanism can be used to handle the case where the new protocol is not supported by the target. More on this mechanism in this section of the OTEP.

The experimental collector implements on top of this library a new Arrow Receiver and Exporter able to fallback on standard OTLP when needed. The following diagram is an overview of this integration. The internal representation of the data has not been updated and this collector is still fundamentally row-oriented internally.

Note 2: A future phase 2 of this project will focus on implementing end-to-end OTel Arrow to improve the overall performance.

Developers

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change. For more information, please read CONTRIBUTING.

How to change the protobuf specification

To (re)generate the ArrowStreamService gRPC service, you need to install the protoc compiler and the protoc-gen-grpc plugin.

go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.28
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.2
export PATH="$PATH:$(go env GOPATH)/bin"
cd ./proto
./generate.sh

Once the *.pb.go files are generated, you need to replace the content of the api/collector/arrow/v1 directory by the generated files present in the ./proto/api/collector/arrow/v1 directory.

Integration with the OpenTelemetry Collector

The integration of this package with the OpenTelemetry Collector is done in the following experimental repository:

• experimental-arrow-collector

This above repository houses a fork of the entire core OpenTelemetry Collector, where the complete branch history is kept, including "mainline" Collector commits as well as Arrow-component development commits.

Because that repository contains portions that are not part of the OTel-Arrow project, the components are being maintained in this repository until they can be merged into the OpenTemetry-Collector-Contrib repository.

Collector components copied from that repository are currently available in the ./collector sub-package of this repository.

Examples demonstrating how to configure and test an OpenTelemetry Collector with OTel-Arrow exporter and receiver components are located in ./collector/examples, including:

• examples/bridge: A compression bridge between "edge" and "saas" collectors.
• examples/metadata-bridge: A compression bridge between "edge" and "saas" collectors with metadata support, allowing request headers to transit via OTel-Arrow.
• examples/loopback: A collector that writes Arrow to and from itself.
• examples/recorder: A collector with support for recording data files for diagnostic and benchmark purposes.
• examples/synthesize: A collector with support for synthesizing telemetry data using a telemetry-generator component.

License

OTel Arrow Protocol Adapter is licensed under Apache 2.0.