Observability by Design

This repository is a demonstration of the capabilities of OpenTelemetry Weaver for designing your observability.

The key principle is treating observability (metrics, logs, spans, etc.) just as you would an API.

This project demonstrates the following key capabilities of weaver:

• weaver registry check: Ensures defined observability signals match policies (e.g. backwards compatibility)
• weaver registry generate: Creates example applications.

sides from Observability Day EU 2025 talk

Example Application

The example application is a dead simple HTTP service that provides "auction" capabilities. New bids are posted to the /auction/{auction_id}/bid endpoint.

This example showed tracking bids via metrics and spans.

• Spans leverage OOTB http semantic conventions from the OpenTelemetry project.
• Metrics use a newly deifned auction.bid.count metric, defined in the o11y directory.

Directory layout

• The o11y/ directory contains all defined observability signals specific to this application.
• THe docs/o11y directory contains autogenerated documentation about the defined metric.
• The go/o11y directory contains autogenerated Go library that will simplify writing all defined metrics in the project.
• The policies/ directory contains policies that will be enforced on observability signal definitions.
• The templates/registry directory contains templates for autogenerating documentation and code.
  • templates/registry/markdown contains documenation generatoin templates.
  • templates/registry/go contains Go code generation templates.
  • templates/registry/rust contains Rust code generation templates.
• go/ contains the Go example application code.

Building

1. Generate code for Go: make generate-go
2. Generate code for Rust: make generate-rust

Running

1. Running the Go Example
   • Move to the go directory: cd go
   • Run the go server go run .
   • In a separate terminal, issue some requests curl localhost:8080/auction/1/bid e.g.
   • Check the prometheus metrics: curl localhost:2223/metrics
2. Running the Rust Example TODO

Generating Docs

Run make generate-docs.

All docs in the docs/ directory will be updated.

Verify Policy

Run make check and all defined policies for Weaver will be checked against defined telemetry.

Note: We recommend including policy checks in CI/CD pipelines.