chore(ci): run cargo machete to catch unused dependencies

.github/workflows/rust.yml

@@ -249,7 +249,26 @@
           # (or 'taplo format') locally to fix the formatting, then commit the result.
           ci/scripts/rust_toml_fmt.sh
 
+  cargo-machete:
+    name: Check for unused dependencies
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7.0.1
+        with:
+          fetch-depth: 1
+      - name: Install cargo-machete
+        uses: taiki-e/install-action@742a3317eac7bd62f91cd888b4eead5e784ba833 # v2.87.1
+        with:
+          tool: cargo-machete@0.9.2
+
+      - name: Check for unused dependencies
+        run: |
+          # if a reported dependency is a false positive (e.g. only referenced
+          # through macros or generated code), add it to the crate's
+          # `[package.metadata.cargo-machete]` ignored list with a comment.
+          ci/scripts/rust_machete.sh
+
   datafusion-proto-sync-check:
     name: Check vendored DataFusion proto is in sync
     runs-on: ubuntu-latest
     steps:

Cargo.toml

@@ -61,7 +61,6 @@ object_store = "0.13.2"
 ordered-float = "5"
 pastey = "0.2.3"
 prost = "0.14"
-prost-types = "0.14"
 rstest = { version = "0.26" }
 tonic = { version = "0.14" }
 tonic-build = { version = "0.14", default-features = false, features = [

ballista-cli/Cargo.toml

@@ -31,6 +31,13 @@ readme = "README.md"
 [lib]
 crate-type = ["cdylib", "rlib"]
 
+[package.metadata.cargo-machete]
+ignored = [
+    # not imported directly; provides the `critical-section` implementation that
+    # ratatui-core needs at link time in the wasm32 `web` build
+    "critical-section",
+]
+
 [dependencies]
 # CLI-only deps (DataFusion/Ballista) — gated by `cli` feature
 ballista = { path = "../ballista/client", version = "54.0.0", features = ["standalone"], optional = true }
@@ -59,7 +66,6 @@ url-escape = { workspace = true, optional = true }
 
 # Native-only TUI deps
 crossterm = { version = "0.29.0", features = ["event-stream"], optional = true }
-tracing-appender = { version = "0.2", optional = true }
 
 # Web-only deps (WASM)
 console_error_panic_hook = { version = "0.1", optional = true }
@@ -102,7 +108,6 @@ tui = [
     "dep:reqwest",
     "dep:serde",
     "dep:serde_json",
-    "dep:tracing-appender",
     "dep:tui-shimmer",
     "ratatui/crossterm",
     "ratatui/all-widgets",

ballista/core/Cargo.toml

@@ -36,7 +36,7 @@ rustc-args = ["--cfg", "docsrs"]
 
 [features]
 arrow-ipc-optimizations = []
-build-binary = ["aws-config", "aws-credential-types", "clap", "object_store"]
+build-binary = ["clap", "object_store"]
 default = ["arrow-ipc-optimizations"]
 docsrs = []
 # Used for testing ONLY: causes all values to hash to the same value (test for collisions)
@@ -46,8 +46,6 @@ spark-compat = ["dep:datafusion-spark"]
 [dependencies]
 arrow-flight = { workspace = true }
 async-trait = { workspace = true }
-aws-config = { version = "1.8.18", optional = true }
-aws-credential-types = { version = "1.2.0", optional = true }
 chrono = { version = "0.4", default-features = false }
 clap = { workspace = true, optional = true }
 datafusion = { workspace = true }
@@ -57,12 +55,10 @@ datafusion-spark = { workspace = true, optional = true, features = ["datafusion"
 futures = { workspace = true }
 itertools = "0.15"
 log = { workspace = true }
-md-5 = { version = "^0.11.0" }
 object_store = { workspace = true, features = ["aws", "http"], optional = true }
 parking_lot = { workspace = true }
 pastey = { workspace = true }
 prost = { workspace = true }
-prost-types = { workspace = true }
 rand = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
 tokio = { workspace = true, features = ["rt-multi-thread"] }

ballista/executor/Cargo.toml

@@ -27,6 +27,13 @@ authors = ["Apache DataFusion <dev@datafusion.apache.org>"]
 edition = { workspace = true }
 rust-version = { workspace = true }
 
+[package.metadata.cargo-machete]
+ignored = [
+    # not imported directly; pulls in arrow's `ipc_compression` feature so the arrow
+    # crates used through datafusion can compress shuffle IPC data
+    "arrow",
+]
+
 [[bin]]
 name = "ballista-executor"
 path = "src/bin/main.rs"
@@ -38,7 +45,6 @@ build-binary = [
     "clap",
     "tracing-subscriber",
     "tracing-appender",
-    "tracing",
     "ballista-core/build-binary",
     "mimalloc",
     "dep:axum",
@@ -70,7 +76,6 @@ tokio = { workspace = true, features = ["full"] }
 tokio-stream = { workspace = true, features = ["net"] }
 tokio-util = { version = "0.7", features = ["io-util"] }
 tonic = { workspace = true }
-tracing = { workspace = true, optional = true }
 tracing-appender = { workspace = true, optional = true }
 tracing-subscriber = { workspace = true, optional = true }
 uuid = { workspace = true }

ballista/scheduler/Cargo.toml

@@ -27,6 +27,14 @@ authors = ["Apache DataFusion <dev@datafusion.apache.org>"]
 edition = { workspace = true }
 rust-version = { workspace = true }
 
+[package.metadata.cargo-machete]
+ignored = [
+    # used via the `ballista_core::assert_plan!` macro, which expands to `insta::assert_snapshot!`
+    "insta",
+    # used by the `keda-scaler` gRPC code generated into OUT_DIR by build.rs
+    "tonic-prost",
+]
+
 [[bin]]
 name = "ballista-scheduler"
 path = "src/bin/main.rs"
@@ -66,15 +74,13 @@ ferroid = { version = "2.0", features = ["alloc", "std", "snowflake", "atomic",
 futures = { workspace = true }
 graphviz-rust = { version = "0.9", optional = true }
 http = "1.4"
-insta = { workspace = true }
 itertools = { workspace = true }
 log = { workspace = true }
 object_store = { workspace = true }
 once_cell = { version = "1.21.4", optional = true }
 parking_lot = { workspace = true }
 prometheus = { version = "0.14", features = ["process"], optional = true }
 prost = { workspace = true }
-prost-types = { workspace = true }
 rand = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
 serde_json = { version = "1", optional = true }
@@ -94,6 +100,7 @@ name = "tpch_plan_stability"
 path = "tests/tpch_plan_stability/main.rs"
 
 [dev-dependencies]
+insta = { workspace = true }
 regex = "1"
 rstest = { workspace = true }
 serde_json = "1"

ci/scripts/rust_machete.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# Checks for unused dependencies. Install with `cargo install cargo-machete`.
+# False positives can be added to the `[package.metadata.cargo-machete]`
+# `ignored` list of the crate's Cargo.toml, with a comment explaining why
+# the dependency is needed.
+
+set -ex
+cargo machete

dev/msrvcheck/Cargo.toml

@@ -22,6 +22,12 @@ edition = "2024"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[package.metadata.cargo-machete]
+ignored = [
+    # not imported; pins the transitive `time` version so `cargo` keeps compiling
+    "time",
+]
+
 [dependencies]
 cargo = "0.97.1"
 time = "=0.3.47" # time 0.3.48 introduced an associated-type From impl that conflicts with cargo-credential's blanket From impl

dev/rust_lint.sh

@@ -21,3 +21,4 @@ set -e
 ci/scripts/rust_fmt.sh
 ci/scripts/rust_clippy.sh
 ci/scripts/rust_toml_fmt.sh
+ci/scripts/rust_machete.sh

python/Cargo.toml

@@ -30,7 +30,6 @@ include = ["/src", "/ballista", "/LICENSE.txt", "pyproject.toml", "Cargo.toml",
 publish = false
 
 [dependencies]
-async-trait = "0.1.89"
 # ballista = { path = "../ballista/client", version = "54.0.0" }
 # ballista-core = { path = "../ballista/core", version = "54.0.0" }
 # ballista-executor = { path = "../ballista/executor", version = "54.0.0", default-features = false }