# env-var-proof

Answers one factual question with real execution instead of quoting a changelog: does Spring
Boot 4.1 actually honor standard `OTEL_*` environment variables that Boot 4.0 did not?

`boot40/` and `boot41/` contain the **identical** `OtelEnvProofApplication.java` -- the only
difference between the two Maven modules is the `spring-boot-starter-parent` version (4.0.8 vs
4.1.1). Both start with only `OTEL_EXPORTER_OTLP_ENDPOINT` and `OTEL_METRIC_EXPORT_INTERVAL` set
(no `management.otlp.*` Spring properties anywhere) and point at `stub-receiver/`, a
dependency-free stand-in for an OTLP collector that just logs every POST it receives.

See [`../docs/output/04-otel-env-vars-4.0-vs-4.1.txt`](../docs/output/04-otel-env-vars-4.0-vs-4.1.txt)
for the captured result, and [`../docs/03-otel-env-vars.md`](../docs/03-otel-env-vars.md) for the
write-up. Run it yourself with [`../scripts/run-env-var-proof.sh`](../scripts/run-env-var-proof.sh).