Add declarative configuration initial version

Cargo.toml

@@ -4,6 +4,7 @@ members = [
     "opentelemetry-*",
     "opentelemetry-*/examples/*",
     "opentelemetry-otlp/tests/*",
+    "opentelemetry-declarative-config",
     "examples/*",
     "stress",
 ]

opentelemetry-declarative-config/CHANGELOG.md

@@ -0,0 +1,9 @@
+# Changelog
+
+## vNext
+
+## v0.1.0
+
+### Added
+
+- Initial declarative configuration

opentelemetry-declarative-config/Cargo.toml

@@ -0,0 +1,47 @@
+[package]
+name = "opentelemetry-declarative-config"
+version = "0.29.1"
+description = "Declarative configuration for OpenTelemetry SDK"
+homepage = "https://github.com/open-telemetry/opentelemetry-rust/tree/main/opentelemetry-declarative-config"
+repository = "https://github.com/open-telemetry/opentelemetry-rust/tree/main/opentelemetry-declarative-config"
+readme = "README.md"
+categories = [
+    "development-tools::debugging",
+    "development-tools::profiling",
+]
+keywords = ["opentelemetry", "declarative", "metrics", "configuration"]
+license = "Apache-2.0"
+edition = "2021"
+rust-version = "1.75.0"
+
+[package.metadata.docs.rs]
+all-features = true
+rustdoc-args = ["--cfg", "docsrs"]
+
+[dependencies]
+opentelemetry = { version = "0.31.0" }
+opentelemetry_sdk = { version = "0.31.0", features = ["experimental_metrics_custom_reader"] }
+opentelemetry-stdout = { version = "0.31.0" }
+opentelemetry-otlp = { version = "0.31.0" }
+opentelemetry-http = { workspace = true, optional = true, default-features = false }
+serde = { workspace = true, features = ["derive"] }
+reqwest = { workspace = true, optional = true }
+serde_yaml = "0.9.34"
+
+[dev-dependencies]
+tokio = { workspace = true, features = ["macros", "rt-multi-thread"] }
+
+[features]
+tonic-client = ["opentelemetry-otlp/grpc-tonic", "opentelemetry-otlp/trace", "opentelemetry-otlp/logs", "opentelemetry-otlp/metrics"]
+hyper-client = ["opentelemetry-http/hyper"]
+reqwest-client = ["reqwest", "opentelemetry-http/reqwest"]
+reqwest-blocking-client = ["reqwest/blocking", "opentelemetry-http/reqwest-blocking"]
+
+# Keep tonic as the default client
+default = ["tonic-client"]
+
+[package.metadata.cargo-machete]
+ignored = [
+    "reqwest", # needed for otlp features
+    "opentelemetry-http" # needed for otlp features
+]

opentelemetry-declarative-config/README.md

@@ -0,0 +1,30 @@
+# OpenTelemetry Declarative Configuration
+
+![OpenTelemetry — An observability framework for cloud-native software.][splash]
+
+[splash]: https://raw.githubusercontent.com/open-telemetry/opentelemetry-rust/main/assets/logo-text.png
+
+Declarative configuration for applications instrumented with [`OpenTelemetry`]. 
+
+## OpenTelemetry Overview
+
+OpenTelemetry is an Observability framework and toolkit designed to create and
+manage telemetry data such as traces, metrics, and logs. OpenTelemetry is
+vendor- and tool-agnostic, meaning that it can be used with a broad variety of
+Observability backends, including open source tools like [Jaeger] and
+[Prometheus], as well as commercial offerings.
+
+OpenTelemetry is *not* an observability backend like Jaeger, Prometheus, or other
+commercial vendors. OpenTelemetry is focused on the generation, collection,
+management, and export of telemetry. A major goal of OpenTelemetry is that you
+can easily instrument your applications or systems, no matter their language,
+infrastructure, or runtime environment. Crucially, the storage and visualization
+of telemetry is intentionally left to other tools.
+
+[`Prometheus`]: https://prometheus.io
+[`OpenTelemetry`]: https://crates.io/crates/opentelemetry
+[`Jaeger`]: https://www.jaegertracing.io
+
+## Release Notes
+
+You can find the release notes (changelog) [here](https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry-declarative-config/CHANGELOG.md).

opentelemetry-declarative-config/examples/declarative_basic.rs

@@ -0,0 +1,44 @@
+use opentelemetry_declarative_config::Configurator;
+
+/// Example of configuring OpenTelemetry telemetry using declarative YAML configuration.
+
+#[tokio::main]
+pub async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let configurator = Configurator::new();
+    let config_yaml = r#"
+        metrics:
+            readers:
+                - periodic:
+                    exporter:
+                        otlp:
+                            protocol: http/protobuf
+                            endpoint: https://backend:4318
+                        stdout:
+                            temporality: cumulative
+        logs:
+            processors:
+                - batch:
+                    exporter:
+                        stdout:
+                        otlp:
+                            protocol: http/protobuf
+                            endpoint: https://backend:4318
+        resource:
+            service.name: sample-service
+            service.version: "1.0.0"
+    "#;
+    let result = configurator.configure_telemetry_from_yaml(config_yaml.into());
+    if let Err(ref e) = result {
+        panic!("Failed to configure telemetry from YAML string: {}", e);
+    }
+    assert!(result.is_ok());
+    let telemetry_providers = result.unwrap();
+    assert!(telemetry_providers.meter_provider().is_some());
+    assert!(telemetry_providers.logs_provider().is_some());
+    assert!(telemetry_providers.traces_provider().is_none());
+
+    println!("All the expected telemetry providers were configured successfully. Shutting down...");
+
+    telemetry_providers.shutdown()?;
+    Ok(())
+}