fix: Backport opentelemetry 0.18 code from main repo (#9)

## Motivation
I noticed that this repo got the cut-off before opentelemetry 0.18 was
committed into the main repo so I tried to backport what was there.

## Solution
This is pretty much a backport from the code that @jtescher did on the
main repo.

Let me know if you see something wrong, I tried to adapt the rejections
the best way possible.

This fix #8

---------

Signed-off-by: Jayson Reis <[email protected]>
Co-authored-by: Julian Tescher <[email protected]>

Cargo.toml

@@ -17,15 +17,15 @@ categories = [
 keywords = ["tracing", "opentelemetry", "jaeger", "zipkin", "async"]
 license = "MIT"
 edition = "2018"
-rust-version = "1.46.0"
+rust-version = "1.56.0"
 
 [features]
 default = ["tracing-log", "metrics"]
 # Enables support for exporting OpenTelemetry metrics
 metrics = ["opentelemetry/metrics"]
 
 [dependencies]
-opentelemetry = { version = "0.17.0", default-features = false, features = ["trace"] }
+opentelemetry = { version = "0.18.0", default-features = false, features = ["trace"] }
 tracing = { version = "0.1.35", default-features = false, features = ["std"] }
 tracing-core = "0.1.28"
 tracing-subscriber = { version = "0.3.0", default-features = false, features = ["registry", "std"] }
@@ -39,7 +39,7 @@ thiserror = { version = "1.0.31", optional = true }
 [dev-dependencies]
 async-trait = "0.1.56"
 criterion = { version = "0.3.6", default-features = false }
-opentelemetry-jaeger = "0.16.0"
+opentelemetry-jaeger = "0.17.0"
 tracing = { version = "0.1.35", default-features = false, features = ["std", "attributes"] }
 tracing-subscriber = { version = "0.3.0", default-features = false, features = ["registry", "std"] }
 futures-util = { version = "0.3", default-features = false }

README.md

@@ -50,7 +50,7 @@ The crate provides the following types:
 [`tracing`]: https://crates.io/crates/tracing
 [OpenTelemetry]: https://opentelemetry.io/
 
-*Compiler support: [requires `rustc` 1.49+][msrv]*
+*Compiler support: [requires `rustc` 1.56+][msrv]*
 
 [msrv]: #supported-rust-versions
 
@@ -110,7 +110,7 @@ $ firefox http://localhost:16686/
 ## Supported Rust Versions
 
 Tracing Opentelemetry is built against the latest stable release. The minimum
-supported version is 1.46. The current Tracing version is not guaranteed to
+supported version is 1.56. The current Tracing version is not guaranteed to
 build on Rust versions earlier than the minimum supported version.
 
 Tracing follows the same compiler support policies as the rest of the Tokio

examples/opentelemetry.rs

@@ -18,7 +18,7 @@ fn main() -> Result<(), Box<dyn Error + Send + Sync + 'static>> {
     // Install an otel pipeline with a simple span processor that exports data one at a time when
     // spans end. See the `install_batch` option on each exporter's pipeline builder to see how to
     // export in batches.
-    let tracer = opentelemetry_jaeger::new_pipeline()
+    let tracer = opentelemetry_jaeger::new_agent_pipeline()
         .with_service_name("report_example")
         .install_simple()?;
     let opentelemetry = tracing_opentelemetry::layer().with_tracer(tracer);