chore: Prepare docs before 0.29

Author: cijothomas

README.md

@@ -31,12 +31,12 @@ documentation.
 | Signal/Component      | Overall Status     |
 | --------------------  | ------------------ |
 | Context               | Beta               |
-| Baggage               | Beta               |
+| Baggage               | RC                 |
 | Propagators           | Beta               |
 | Logs-API              | Stable*            |
-| Logs-SDK              | RC                 |
+| Logs-SDK              | Stable              |
 | Logs-OTLP Exporter    | RC                 |
-| Logs-Appender-Tracing | RC                 |
+| Logs-Appender-Tracing | Stable             |
 | Metrics-API           | Stable             |
 | Metrics-SDK           | RC                 |
 | Metrics-OTLP Exporter | RC                 |

docs/migration_0.29.md

@@ -0,0 +1,86 @@
+# Migration Guide from 0.28 to 0.29
+
+OpenTelemetry Rust 0.29 introduces few breaking changes. This guide aims to
+facilitate a smooth migration for common use cases involving the
+`opentelemetry`, `opentelemetry_sdk`, `opentelemetry-otlp`, and
+`opentelemetry-appender-tracing` crates. For a comprehensive list of changes,
+please refer to the detailed changelog for each crate. This document covers only
+the most common scenarios. Note that changes that only affect
+custom exporter/processor authors are not mentioned in this doc.
+
+OpenTelemetry Metrics API, Log-Bridge API were declared stable in 0.28,
+and has no breaking changes.
+
+## Baggage Changes
+
+The Baggage API has been redesigned to align with the OpenTelemetry
+specification. While the core API for interacting with Baggage remains the same,
+the accepted data types have changed. Baggage Keys now only allow strings (ASCII
+visual characters), and Baggage values are restricted to strings.
+
+For detailed changes, see the [changelog](../opentelemetry/CHANGELOG.md). With
+version 0.29, the Baggage API has reached "Release Candidate" status, meaning
+further breaking changes will be highly restricted.
+
+## Appender-Tracing Changes
+
+The `opentelemetry-appender-tracing` crate, which bridges `tracing` events to
+OpenTelemetry logs, has been updated to properly map `tracing` data types to the
+OpenTelemetry model. As of version 0.29, this crate is considered "Stable," and
+no further breaking changes will be made without a major version bump.
+
+## Configuration via Environment Variables
+
+The 0.29 release aligns OpenTelemetry Rust with the rest of the OpenTelemetry
+ecosystem by treating any code-based configuration as final (i.e., it cannot be
+overridden by environment variables). This policy was partially true before but
+is now applied consistently. If you prefer to configure your application via
+environment variables, avoid configuring it programmatically.
+
+## Discontinuing Dedicated Prometheus Exporter
+
+The `opentelemetry-prometheus` crate will be discontinued with the 0.29 release.
+Active development on this crate ceased a few months ago. Given that Prometheus
+now natively supports OTLP, and considering that the OpenTelemetry Rust project
+is still working towards a 1.0 release, we need to focus on essential components
+to maintain scope and ensure timely delivery.
+
+Prometheus interoperability remains a key goal for OpenTelemetry. However, the
+current `opentelemetry-prometheus` crate requires a major rewrite to eliminate
+dependencies on unmaintained crates. We may reintroduce a dedicated Prometheus
+exporter in the future once these issues are resolved.
+
+For those using Prometheus as a backend, you can integrate with Prometheus using
+the following methods:
+
+1. Use the OTLP Exporter to push metrics directly to Prometheus.
+2. If you require a pull (scrape) model, push metrics to an OpenTelemetry
+   Collector using the OTLP Exporter, and configure Prometheus to scrape the
+   OpenTelemetry Collector.
+
+These alternatives ensure continued Prometheus integration while allowing us to
+focus on achieving a stable 1.0 release for OpenTelemetry Rust.
+
+## Next Release
+
+In the next release, we expect to stabilize the Metrics SDK and resolve the
+long-standing question of `tokio-tracing` vs. `opentelemetry tracing`.
+
+## Instrumentation Libraries
+
+Unlike other OpenTelemetry language implementations, OpenTelemetry Rust did not
+maintain any instrumentations on its own. This has recently changed with a
+[contribution](https://github.com/open-telemetry/opentelemetry-rust-contrib/pull/202)
+from one of the founding members of the OpenTelemetry Rust project to the
+contrib repo, providing an instrumentation library for
+[`actix-web`](https://github.com/open-telemetry/opentelemetry-rust-contrib/tree/main/actix-web-opentelemetry).
+We expect this instrumentation to eventually showcase best practices for
+instrumentation.
+
+We welcome more contributions for instrumentations to the contrib repo.
+
+## Thanks
+
+Thanks to everyone who helped with this milestone. Please share your feedback
+via GitHub issues or the OTel-Rust Slack channel
+[here](https://cloud-native.slack.com/archives/C03GDP0H023).

opentelemetry/CHANGELOG.md

@@ -5,7 +5,6 @@
 - *Breaking* Moved `ExportError` trait from `opentelemetry::trace::ExportError` to `opentelemetry_sdk::export::ExportError`
 - *Breaking* Moved `TraceError` enum from `opentelemetry::trace::TraceError` to `opentelemetry_sdk::trace::TraceError`
 - *Breaking* Moved `TraceResult` type alias from `opentelemetry::trace::TraceResult` to `opentelemetry_sdk::trace::TraceResult`
-- {PLACEHOLDER} - Remove the above completely. // TODO fill this when changes are actually in.
 - Bug Fix: `InstrumentationScope` implementation for `PartialEq` and `Hash` fixed to include Attributes also.
 - **Breaking changes for baggage users**: [#2717](https://github.com/open-telemetry/opentelemetry-rust/issues/2717)
   - Changed value type of `Baggage` from `Value` to `StringValue`