ci: add cargo machete and remove unused dependencies (#2864)

Author: gruebel

.github/workflows/ci.yml

@@ -153,3 +153,18 @@ jobs:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
         with:
           fail_ci_if_error: true
+  cargo-machete:
+    continue-on-error: true
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: stable
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-machete
+      - name: cargo machete
+        run: cargo machete

examples/tracing-grpc/Cargo.toml

@@ -23,3 +23,8 @@ tonic = { workspace = true, features = ["server", "codegen", "channel", "prost"]
 
 [build-dependencies]
 tonic-build = { workspace = true }
+
+[package.metadata.cargo-machete]
+ignored = [
+    "prost" # needed for `tonic-build`
+]

opentelemetry-http/Cargo.toml

@@ -28,5 +28,10 @@ reqwest = { workspace = true, features = ["blocking"], optional = true }
 tokio = { workspace = true, features = ["time"], optional = true }
 tracing = {workspace = true, optional = true}
 
+[package.metadata.cargo-machete]
+ignored = [
+    "tracing" # needed for `internal-logs`
+]
+
 [lints]
 workspace = true

opentelemetry-jaeger-propagator/Cargo.toml

@@ -32,5 +32,10 @@ opentelemetry = { features = ["testing"], path = "../opentelemetry" }
 default = ["internal-logs"]
 internal-logs = ["tracing"]
 
+[package.metadata.cargo-machete]
+ignored = [
+    "tracing" # needed for `internal-logs`
+]
+
 [lints]
 workspace = true

opentelemetry-otlp/Cargo.toml

@@ -26,7 +26,6 @@ all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
 
 [dependencies]
-futures-core = { workspace = true }
 opentelemetry = { version = "0.29", default-features = false, path = "../opentelemetry" }
 opentelemetry_sdk = { version = "0.29", default-features = false, path = "../opentelemetry-sdk" }
 opentelemetry-http = { version = "0.29", path = "../opentelemetry-http", optional = true }

opentelemetry-otlp/tests/integration_test/Cargo.toml

@@ -11,7 +11,6 @@ opentelemetry-proto = { path = "../../../opentelemetry-proto", features = ["gen-
 tokio = { workspace = true, features = ["full"] }
 serde_json = { workspace = true }
 testcontainers = { workspace = true, features = ["http_wait"] }
-once_cell.workspace = true
 anyhow = { workspace = true }
 ctor = { workspace = true }
 uuid = { workspace = true, features = ["v4"] }

opentelemetry-prometheus/Cargo.toml

@@ -38,3 +38,8 @@ tokio = { version = "1", features = ["full"] }
 default = ["internal-logs"]
 prometheus-encoding = []
 internal-logs = ["tracing"]
+
+[package.metadata.cargo-machete]
+ignored = [
+    "tracing" # needed for `internal-logs`
+]

opentelemetry-proto/Cargo.toml

@@ -66,5 +66,10 @@ prost-build = { workspace = true }
 tempfile = { workspace = true }
 serde_json = { workspace = true }
 
+[package.metadata.cargo-machete]
+ignored = [
+    "tracing" # needed for `internal-logs`
+]
+
 [lints]
 workspace = true

opentelemetry-sdk/Cargo.toml

@@ -58,6 +58,10 @@ experimental_logs_concurrent_log_processor = ["logs"]
 experimental_trace_batch_span_processor_with_async_runtime = ["trace"]
 experimental_metrics_disable_name_validation = ["metrics"]
 
+[package.metadata.cargo-machete]
+ignored = [
+    "tracing" # needed for `internal-logs`
+]
 
 [[bench]]
 name = "context"

opentelemetry-stdout/Cargo.toml

@@ -21,13 +21,12 @@ rustdoc-args = ["--cfg", "docsrs"]
 
 [features]
 default = ["trace", "metrics", "logs"]
-trace = ["opentelemetry/trace", "opentelemetry_sdk/trace", "futures-util"]
+trace = ["opentelemetry/trace", "opentelemetry_sdk/trace"]
 metrics = ["opentelemetry/metrics", "opentelemetry_sdk/metrics"]
 logs = ["opentelemetry/logs", "opentelemetry_sdk/logs", "opentelemetry_sdk/spec_unstable_logs_enabled"]
 
 [dependencies]
 chrono = { workspace = true, features = ["now"] }
-futures-util = { workspace = true, optional = true }
 opentelemetry = { version = "0.29", path = "../opentelemetry" }
 opentelemetry_sdk = { version = "0.29", path = "../opentelemetry-sdk" }