ci: fail on unused dependencies (cargo-udeps)

.github/workflows/tests.yml

@@ -195,3 +195,48 @@ jobs:
 
       - name: Check formatting
         run: cargo fmt -- --check
+
+  udeps:
+    name: Unused dependency check
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust (nightly for cargo-udeps)
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: nightly
+
+      - name: Setup Rust cache
+        uses: Swatinem/rust-cache@v2
+        with:
+          shared-key: ${{ runner.os }}
+
+      - name: Install cargo-udeps
+        uses: taiki-e/install-action@cargo-udeps
+
+      - name: Check for unused dependencies
+        run: |
+          set -euo pipefail
+          # Run with nightly; capture output without failing the step
+          set +e
+          cargo +nightly udeps --all-targets --all-features 2>&1 | tee udeps_output.txt
+          STATUS=$?
+          set -e
+          cat udeps_output.txt
+          # If cargo-udeps failed due to nightly requirement or other errors, surface that
+          if [ $STATUS -ne 0 ]; then
+            echo "cargo-udeps exited with status $STATUS"
+            # If unused deps are present, cargo-udeps typically exits non-zero; still explicitly check text
+            if grep -qi "unused" udeps_output.txt; then
+              echo "Unused dependencies detected"
+              exit 1
+            fi
+            exit $STATUS
+          fi
+          # Treat any mention of 'unused' as a failure signal
+          if grep -qi "unused" udeps_output.txt; then
+            echo "Unused dependencies detected"
+            exit 1
+          fi

Cargo.toml

@@ -19,11 +19,9 @@ tokio = { version = "1.35", features = ["full"] }
 hyper = { version = "1.7", features = ["full"] }
 hyper-util = { version = "0.1", features = ["full"] }
 http-body-util = "0.1"
-tower = { version = "0.5", features = ["full"] }
 bytes = "1.5"
 tokio-rustls = "0.26"
 rustls = "0.23"
-rustls-pemfile = "2.0"
 rcgen = "0.13"
 webpki-roots = "0.26"
 lru = "0.12"
@@ -32,9 +30,6 @@ anyhow = "1.0"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter", "chrono"] }
 chrono = "0.4"
-serde = { version = "1.0", features = ["derive"] }
-serde_yaml = "0.9"
-serde_json = "1.0"
 dirs = "6.0.0"
 hyper-rustls = "0.27.7"
 tls-parser = "0.12.2"
@@ -53,4 +48,4 @@ libc = "0.2"
 tempfile = "3.8"
 assert_cmd = "2.0"
 predicates = "3.0"
-serial_test = "3.0"
+serial_test = "3.0"