Injecting tracing the hot way

An exploration of runtime tracing in Elixir/Erlang using BEAM fundamentals. The author introduces updates to Entrace, an Erlang tracing library, including a mini single-module version you can paste into an iex console and a one-liner that downloads and hot-loads pre-compiled .beam files into a running system. A second library, entrace_opentelemetry, bridges Erlang's native tracing with OpenTelemetry spans, enabling runtime injection of distributed tracing into production apps without a redeploy — including conditional tracing based on argument values.