opentelemetry-exporter-otlp-metrics 0.15.0: Histogram Env Var and Redirect Fixes

The opentelemetry-ruby project published opentelemetry-exporter-otlp-metrics 0.15.0 on October 20, 2026. It is a small release with two changes that both matter if you run the OTLP metrics exporter in production: configurable default histogram aggregation and working HTTP redirect handling.

The full release notes and gem details are on the GitHub release page.

Configure default histogram aggregation

The exporter now supports the OTEL_EXPORTER_OTLP_METRICS_DEFAULT_HISTOGRAM_AGGREGATION environment variable (PR #2389). This matches the OpenTelemetry specification for OTLP metrics exporters.

In practice, this means you can switch the default aggregation for histogram instruments without touching code. Set the variable to explicit_bucket_histogram or exponential_bucket_histogram in your deployment environment, and the exporter picks it up. If you are tuning cardinality on high volume metrics, controlling this from configuration is the convenient path.

HTTP redirects are now followed

The exporter follows HTTP redirects instead of failing on them (PR #2411 is the aggregation change; the redirect fix is #2411). This matters behind proxies and load balancers that respond with a 301 or 302 when endpoints move. Before this fix, such responses would surface as export errors. Now the exporter retries against the new location.

Upgrade notes

Nothing here is marked as breaking. This is not a prerelease. If you already run an earlier 0.x version of the exporter, upgrading should be a dependency bump. The new environment variable is opt in, so existing configurations behave the same unless you set it.

Where to get it

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