[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
OpenTelemetry.Exporter.OpenTelemetryProtocol (source)	1.21.0-rc.2 → 1.21.0
OpenTelemetry.Extensions.Hosting (source)	1.21.0-rc.2 → 1.21.0

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Release Notes

open-telemetry/opentelemetry-dotnet (OpenTelemetry.Exporter.OpenTelemetryProtocol)

v1.21.0

Release details: 1.21.0

• Breaking change Dropped support for net8.0 and net9.0. The supported
  .NET targets are now net10.0, net11.0, net462 and netstandard2.0.
• Added support for .NET 11.0, including enabling ActivitySources from
  configuration using the Microsoft.Extensions.Diagnostics tracing APIs
  (for example, services.AddTracing(b => b.AddConfiguration(section))).
  Activities from sources enabled this way are processed by the OpenTelemetry
  TracerProvider registered through AddOpenTelemetry().WithTracing().
  This is not supported when targeting net10.0.
• Breaking change When running on .NET on non-Windows platforms, creating an
  OTLP exporter with the experimental disk retry feature enabled now throws an
  UnauthorizedAccessException if the retry directory could be changed by
  another user. The retry directory must be owned by the current user and must
  not be writable by its group or by other users, and each directory and
  symbolic link in its path must be owned by the current user or by root and
  must not be writable by its group or by other users unless it has the sticky
  bit set (such as /tmp). These checks can be disabled by setting
  OTEL_DOTNET_EXPERIMENTAL_OTLP_DISK_RETRY_CHECK_PERMISSIONS to false.
• Breaking change OTEL_DIAGNOSTICS.json now writes rolling
  otel-dotnet-*.log files in the standard entry format instead of a circular
  {executable}.{pid}.log file. FileSize is split evenly across two retained
  files, FormatMessage is now ignored, and writes are asynchronous and may
  drop entries when the bounded queue fills. Sinks configured through
  providers, including those enabled through environment variables, override
  the JSON configuration with a warning event. The preamble of each file now
  includes configuration warnings and a redacted environment snapshot.
• Breaking change The span status description (Activity.StatusDescription
  or the otel.status_description tag) exported by the OTLP exporter is now
  truncated to the configured span attribute value length limit (for example
  OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT) instead of being exported in full.
• The EnvironmentVariableCarrier APIs previously covered by OTEL1005 are now
  stable. Carrier snapshots now preserve environment variable names, preventing
  extraction from non-normalized aliases and collisions with normalized names,
  and follow the platform's case-sensitivity rules.
• Added support for batching the metric points exported by
  PeriodicExportingMetricReader. Set
  PeriodicExportingMetricReaderOptions.MaxExportBatchSize (or the
  OTEL_METRIC_EXPORT_MAX_BATCH_SIZE environment variable) to split the metric
  points of each collection into batches of at most that many metric points.
• Added Sampler.Shutdown and the overridable Sampler.OnShutdown so samplers
  can release resources. TracerProvider now calls Shutdown on its sampler
  when it is shut down or disposed, and ParentBasedSampler and
  AlwaysRecordSampler call Shutdown on the samplers they delegate to.
• SelfDiagnosticsOptions is now automatically bound from the
  OpenTelemetry:SelfDiagnostics configuration section, when present.
• OpenTelemetryLoggerOptions is now bound from the Logging:OpenTelemetry
  configuration section using the configuration binding source generator
  instead of reflection, making it fully trim and Native AOT compatible.
• The OpenTelemetry providers are now initialized in
  IHostedLifecycleService.StartingAsync instead of IHostedService.StartAsync
  so that telemetry emitted by other hosted services during StartingAsync is
  captured.
• Updated the schema URL of resources created by the SDK and the host
  environment resource detector to use OpenTelemetry Semantic Conventions
  version 1.45.0.
• Improved traceparent extraction throughput on .NET.
• Updated the System.Diagnostics.DiagnosticSource dependency to 11.0.0 for
  all target frameworks.
• Reduced allocations during Accept header negotiation in the Prometheus
  exporters.
• Attribute values implementing IUtf8SpanFormattable (.NET 10+) are now
  formatted directly into the OTLP export buffer instead of through
  ToString().
• The timeout passed to MetricReader.Collect() (for example by
  MeterProvider.ForceFlush()), the ExportTimeoutMilliseconds of
  PeriodicExportingMetricReader and the ExporterTimeoutMilliseconds of
  BatchExportProcessor<T> are now made available to the exporter. The OTLP
  exporter now cancels an export when the shorter of these timeouts and
  OtlpExporterOptions.TimeoutMilliseconds elapses, counting the time taken to
  serialize the telemetry, and fixed in-memory retries exceeding the export
  timeout when a retried request stalls.
• Redacted nonstandard OTLP endpoint paths in internal diagnostic logs.
• Fixed byte[]-valued tags and attributes, array-valued tags containing NaN
  or infinite values, nested arrays and maps, and arrays of string-valued
  key/value pairs being exported incorrectly by the Console, OTLP, Zipkin and
  Prometheus exporters. They are now exported as specified (for example
  byte[] values are Base64-encoded and arrays and maps are JSON-encoded
  instead of being written as a .NET type name).
• Fixed the Prometheus exporters:
  • Producing OpenMetrics scrape responses containing a # UNIT line whose unit
    is not an underscore-separated suffix of the metric family name, which
    caused Prometheus to reject the whole response. The line is now omitted.
  • Producing scrape responses containing the same series more than once, or a
    metric named like a sample generated for another metric, which caused
    Prometheus to reject the whole response. Such series and metrics are now
    dropped and a warning event is written.
  • Triggering a separate metrics collection for each scrape that negotiates a
    different response format within the
    ScrapeResponseCacheDurationMilliseconds window.
  • Scrape clients which stop reading their response delaying other scrapes
    until ScrapeResponseTimeoutMilliseconds elapses.
• Fixed a race where collecting a delta metric concurrently with the creation of
  a new MetricPoint could lose the measurement or export the same series
  twice in a single collection.
• Fixed a race where collecting a cumulative metric concurrently with the
  creation of a new MetricPoint could export a MetricPoint that was not yet
  fully initialized, causing a NullReferenceException when enumerating Tags.
• Fixed an exception when downscaling empty exponential histogram buckets after
  a reset.
• Fixed wildcard matching timeouts that could prevent configured source, meter,
  legacy activity, or metric view patterns from matching, and a name with a
  trailing line feed matching a wildcard pattern which does not end in a
  wildcard.
• Fixed OTEL_RESOURCE_ATTRIBUTES values being decoded as form data, which
  changed a + to a space. Values are now only percent-decoded.
• Fixed initialization failures in the SDK, the OTLP, Zipkin and Prometheus
  exporters and host resource detection when environment variable access is
  denied.
• Fixed tracing callbacks continuing after provider shutdown or disposal on
  older target frameworks.
• Fixed PeriodicExportingMetricReader exporting a collection which was still
  in progress after its exporter had been shut down, and not making its final
  collection when Shutdown() was called before its background task had
  started running on platforms where threading is not available.
• Fixed OTEL_EXPORTER_OTLP_HEADERS (and the Headers option) being decoded
  before it was split into headers, so that a percent-encoded , in a value
  started a new header and encoded leading or trailing whitespace was removed.
• Fixed the retry delay of an OTLP/gRPC response being ignored or misread for
  oversized lengths, fields with an unexpected wire type, repeated fields and
  unpadded Base64 grpc-status-details-bin trailers, and it is now ignored when
  the status code in the details contradicts the grpc-status of the response.
• Fixed unbounded OTLP resource serialization buffer growth and incorrect buffer
  reuse after buffer allocation failures.
• Fixed string attribute values truncated by an attribute value length limit
  ending in half of a surrogate pair. The truncated value now ends before the
  pair instead.
• An OutOfMemoryException thrown while converting an attribute value to a
  string is no longer swallowed and the attribute dropped; it now propagates.
• Fixed a race in the self-diagnostics sink dispatcher where disposing it while
  its pump thread was exiting could throw ArgumentNullException on .NET
  Framework.
• Fixed a dangling comma in a redacted OTEL_RESOURCE_ATTRIBUTES value in the
  self-diagnostics environment snapshot when it contained empty entries.

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