Zack Kayser and Ethan Gunderson, Software Engineers at Cars Commerce, join the Elixir Wizards to share their expertise on telemetry and observability in large-scale systems. Drawing from their experience at Cars.com—a platform handling high traffic and concurrent users—they discuss the technical and organizational challenges of scaling applications, managing microservices, and implementing effective observability practices.

The conversation highlights the pivotal role observability plays in diagnosing incidents, anticipating system behavior, and asking unplanned questions of a system. Zack and Ethan explore tracing, spans, and the unique challenges introduced by LiveView deployments and WebSocket connections.

They also discuss the benefits of OpenTelemetry as a vendor-agnostic instrumentation tool, the significance of Elixir’s telemetry library, and practical steps for developers starting their observability journey. Additionally, Zack and Ethan introduce their upcoming book, Instrumenting Elixir Applications, which will offer guidance on integrating telemetry and tracing into Elixir projects.

Topics Discussed:

Cars.com’s transition to Elixir and scaling solutions
The role of observability in large-scale systems
Uncovering insights by asking unplanned system questions
Managing high-traffic and concurrent users with Elixir
Diagnosing incidents and preventing recurrence using telemetry
Balancing data collection with storage constraints
Sampling strategies for large data volumes
Tracing and spans in observability
LiveView’s influence on deployments and WebSocket behavior
Mitigating downstream effects of socket reconnections
Contextual debugging for system behavior insights
Observability strategies for small vs. large-scale apps
OpenTelemetry for vendor-agnostic instrumentation
Leveraging OpenTelemetry contrib libraries for easy setup
Elixir’s telemetry library as an ecosystem cornerstone
Tracing as the first step in observability
Differentiating observability from business analytics
Profiling with OpenTelemetry Erlang project tools
The value of profiling for performance insights
Making observability tools accessible and impactful for developers

Links Mentioned

https://www.carscommerce.inc/
https://www.cars.com/
https://hexdocs.pm/telemetry/readme.html
https://kubernetes.io/
https://github.com/ninenines/cowboy
https://hexdocs.pm/bandit/Bandit.html
https://hexdocs.pm/broadway/Broadway.html
https://hexdocs.pm/oban/Oban.html
https://www.dynatrace.com/
https://www.jaegertracing.io/
https://newrelic.com/
https://www.datadoghq.com/
https://www.honeycomb.io/
https://fly.io/phoenix-files/how-phoenix-liveview-form-auto-recovery-works/
https://www.elastic.co/
https://opentelemetry.io/
https://opentelemetry.io/docs/languages/erlang/
https://opentelemetry.io/docs/concepts/signals/traces/
https://opentelemetry.io/docs/specs/otel/logs/
https://github.com/runfinch/finch
https://hexdocs.pm/telemetry_metrics/Telemetry.Metrics.html
https://opentelemetry.io/blog/2024/state-profiling
https://www.instrumentingelixir.com/
https://prometheus.io/
https://www.datadoghq.com/dg/monitor/ts/statsd/
https://x.com/kayserzl
https://github.com/zkayser
https://bsky.app/profile/ethangunderson.com
https://github.com/open-telemetry/opentelemetry-collector-contrib

Special Guests: Ethan Gunderson and Zack Kayser.

July 25, 2025: A summer of heat, drought and flooding; 'Western Soul' singer/songwriter at UMS