Customizing OpenTelemetry Collector with OCB: A CNCF Perspective

Introduction

The Cloud Native Computing Foundation (CNCF) has established OpenTelemetry as a critical tool for observability in cloud-native systems. At its core, the OpenTelemetry Collector acts as a middleware for processing telemetry data (logs, metrics, traces) from diverse sources. However, its true power lies in its extensibility, which is where the OpenTelemetry Collector Builder (OCB) comes into play. This article explores how OCB enables the creation of custom Collector distributions, emphasizing its role in optimizing performance, security, and deployment flexibility within the CNCF ecosystem.

Core Concepts of OpenTelemetry Collector

The OpenTelemetry Collector is designed as a modular pipeline composed of four key components:

• Receivers: Accept telemetry data in formats like OTLP, Prometheus, or Logs.
• Processors: Transform, filter, or enrich data.
• Exporters: Convert data to backend-compatible formats (e.g., OTLP, Prometheus, Jaeger).
• Extensions: Support external operations such as authentication or connectivity.

Its modular architecture allows independent development and combination of components, ensuring it acts as a transient data hub rather than a storage solution. This design enables minimal binary size through customizable composition, making it ideal for resource-constrained environments.

OpenTelemetry Collector Builder (OCB): Automated Customization

OCB streamlines the creation of custom Collector binaries by automating the integration of specified components via a manifest.yaml file. The process involves three stages:

1. Manifest Definition: Specify required components (receivers, exporters, processors) and their versions.
2. Code Generation: OCB generates Go code templates based on the Collector API version.
3. Binary Compilation: Standard Go compilation produces the final binary.

OCB supports two primary configuration flags:

• Config Flag: Directly generates a binary from the manifest.
• Skip Compilation Flag: Produces source code for further customization.

Version compatibility is critical, as OCB aligns with Collector API versions to avoid symbol mismatches. While upstream API stability is improving, careful version management remains essential to prevent compatibility issues.

Building Custom Distributions

Component Selection

Custom distributions can integrate upstream components (e.g., OpenTelemetry Core) or third-party modules. Custom components must adhere to Go module standards and implement the newFactory function for integration.

Version Management

Specify component versions (e.g., github.com/open-telemetry/[email protected]) to ensure consistency. However, upstream updates may introduce incompatibilities, requiring proactive testing.

Component Replacement

Use the replaces syntax to substitute defective components with forked versions containing fixes. This is particularly useful for replacing faulty receivers or exporters.

Packaging and Deployment

• Docker Images: Base images on scratch for minimal size, include binaries and TLS certificates, and run as non-root users (USER nonroot).
• Other Formats: Support Debian/RPM packages, GitHub Releases, and AWS ECR.
• Cross-Platform Builds: Leverage GOOS and GOARCH environment variables to generate binaries for Linux, Windows, macOS, Plan9, and BSD. GitHub Actions (e.g., deel/dist-builder) automate release pipelines.

Performance and Security Considerations

Performance Optimization

OCB currently does not support dynamic module loading due to its impact on Collector performance. Static composition is required, emphasizing the need for minimal component inclusion to reduce memory usage and processing overhead. Tools like pprof and otel-metrics can analyze runtime behavior for further optimization.

Security and Maintenance

Custom components must undergo rigorous security checks to prevent vulnerabilities. Regularly updating upstream dependencies ensures compatibility and addresses emerging security risks. For critical fixes not included in upstream releases, manual component replacement or custom modules may be necessary.

Production Readiness

Custom distributions should undergo thorough testing to avoid breaking changes. Comprehensive documentation and automated release workflows are essential for long-term maintenance.

Use Case: TLS Termination Proxy Distribution

A practical example of OCB’s utility is creating a TLS termination proxy distribution:

• Component Configuration: Use OTLP receivers and exporters with TLS termination capabilities. Configuration is specified via files and environment variables.
• Build Process: Define component versions and replacement strategies in manifest.yaml. GitHub Actions automate Docker image generation and release.
• Deployment: The proxy handles encrypted telemetry data, acting as a secure intermediary between services and backend storage.

Conclusion

OCB empowers developers to tailor the OpenTelemetry Collector to specific use cases, balancing flexibility with performance constraints. By leveraging manifest-driven customization, cross-platform builds, and secure packaging, teams can deploy optimized observability solutions within the CNCF ecosystem. Prioritizing version compatibility, security audits, and automated testing ensures robust, production-ready distributions.