Cargo Workflows

mohitmishra786/low-level-dev-skills/skills/rust/cargo-workflows

by mohitmishra786bdc58472fa9fNo license253 starsListed Oct 9, 2026Updated Oct 9, 2026Repository updated 3 months ago

Cargo workflow skill for Rust projects. Use when managing workspaces, feature flags, build scripts, cargo cache, incremental builds, dependency auditing, or CI configuration with Cargo. Activates on queries about cargo workspaces, Cargo.toml features, build.rs, cargo nextest, cargo deny, cargo check vs build, or Cargo.lock management.

Instructions onlySoftware Development DevOps & Cloud

AI-generated overview

Guides agents through Cargo workspaces, feature flags, build scripts, caching, testing, and dependency auditing for Rust projects.

What it does: This skill provides instructions and configuration examples for managing Rust projects with Cargo. It covers workspace setup, feature flags, build.rs directives, incremental builds and CI caching, cargo nextest, dependency auditing with cargo-audit and cargo-deny, and common cargo commands. It produces guidance and sample configuration rather than executable scripts.
When to use it: Use it when setting up or maintaining a Cargo workspace, configuring feature flags or build scripts, speeding up Cargo builds in CI, or auditing Rust dependencies. It is also relevant for questions about cargo nextest, cargo deny, cargo check versus build, or Cargo.lock management.
Requirements: No scripts are included; it is instructions only. Following the examples may require a Rust toolchain with Cargo and optional tools such as cargo-nextest, cargo-audit, cargo-deny, cargo-machete, cargo-expand, and cargo-edit, plus network access to install them.

Cargo Workflows

Purpose

Guide agents through Cargo workspaces, feature management, build scripts (build.rs), CI integration, incremental compilation, and the Cargo tool ecosystem.

Triggers

"How do I set up a Cargo workspace with multiple crates?"
"How do features work in Cargo?"
"How do I write a build.rs script?"
"How do I speed up Cargo builds in CI?"
"How do I audit my Rust dependencies?"
"What is cargo nextest and should I use it?"

Workflow

1. Workspace setup

text

my-project/├── Cargo.toml           # Workspace root├── Cargo.lock           # Single lock file for all members├── crates/│   ├── core/│   │   └── Cargo.toml│   ├── cli/│   │   └── Cargo.toml│   └── server/│       └── Cargo.toml└── tools/    └── codegen/        └── Cargo.toml

my-project/├── Cargo.toml           # Workspace root├── Cargo.lock           # Single lock file for all members├── crates/│   ├── core/│   │   └── Cargo.toml│   ├── cli/│   │   └── Cargo.toml│   └── server/│       └── Cargo.toml└── tools/    └── codegen/        └── Cargo.toml

toml

# Workspace root Cargo.toml[workspace]members = [    "crates/core",    "crates/cli",    "crates/server",    "tools/codegen",]resolver = "2"   # Feature resolver v2 (required for edition 2021)
# Shared dependency versions (workspace.dependencies)[workspace.dependencies]serde = { version = "1", features = ["derive"] }tokio = { version = "1", features = ["full"] }anyhow = "1"
# Shared profile settings[profile.release]lto = "thin"codegen-units = 1

# Workspace root Cargo.toml[workspace]members = [    "crates/core",    "crates/cli",    "crates/server",    "tools/codegen",]resolver = "2"   # Feature resolver v2 (required for edition 2021)
# Shared dependency versions (workspace.dependencies)[workspace.dependencies]serde = { version = "1", features = ["derive"] }tokio = { version = "1", features = ["full"] }anyhow = "1"
# Shared profile settings[profile.release]lto = "thin"codegen-units = 1

toml

# Member Cargo.toml[package]name = "myapp-core"version.workspace = trueedition.workspace = true
[dependencies]serde.workspace = true    # Inherit from workspaceanyhow.workspace = true

# Member Cargo.toml[package]name = "myapp-core"version.workspace = trueedition.workspace = true
[dependencies]serde.workspace = true    # Inherit from workspaceanyhow.workspace = true

2. Feature flags

toml

[features]default = ["std"]
# Simple flagstd = []
# Feature that enables another featurefull = ["std", "async", "serde-support"]
# Feature with optional dependencyasync = ["dep:tokio"]serde-support = ["dep:serde", "serde/derive"]
[dependencies]tokio = { version = "1", optional = true }serde = { version = "1", optional = true }

[features]default = ["std"]
# Simple flagstd = []
# Feature that enables another featurefull = ["std", "async", "serde-support"]
# Feature with optional dependencyasync = ["dep:tokio"]serde-support = ["dep:serde", "serde/derive"]
[dependencies]tokio = { version = "1", optional = true }serde = { version = "1", optional = true }

bash

# Build with specific featurescargo build --features "async,serde-support"
# Build with no default featurescargo build --no-default-features
# Build with all featurescargo build --all-features
# Check feature combinationscargo check --no-default-featurescargo check --all-features

# Build with specific featurescargo build --features "async,serde-support"
# Build with no default featurescargo build --no-default-features
# Build with all featurescargo build --all-features
# Check feature combinationscargo check --no-default-featurescargo check --all-features

Feature gotchas:

Features are additive: once enabled anywhere in the dependency graph, they stay enabled
resolver = "2" prevents feature leakage between dev-dependencies and regular deps
Use dep:optional_dep syntax (edition 2021) to avoid implicit feature creation

3. Build scripts (build.rs)

rust

// build.rs (at crate root, runs before compilation)use std::env;use std::path::PathBuf;
fn main() {    // Re-run if these files change    println!("cargo:rerun-if-changed=build.rs");    println!("cargo:rerun-if-changed=wrapper.h");    println!("cargo:rerun-if-env-changed=MY_LIB_PATH");
    // Link a system library    println!("cargo:rustc-link-lib=mylib");    println!("cargo:rustc-link-search=/usr/local/lib");
    // Pass a cfg flag to Rust code    let target = env::var("TARGET").unwrap();    if target.contains("linux") {        println!("cargo:rustc-cfg=target_os_linux");    }
    // Set environment variable for downstream crates    println!("cargo:rustc-env=MY_GENERATED_VAR=value");
    // Generate bindings with bindgen    let bindings = bindgen::Builder::default()        .header("wrapper.h")        .generate()        .expect("Unable to generate bindings");
    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());    bindings.write_to_file(out_path.join("bindings.rs")).unwrap();}

// build.rs (at crate root, runs before compilation)use std::env;use std::path::PathBuf;
fn main() {    // Re-run if these files change    println!("cargo:rerun-if-changed=build.rs");    println!("cargo:rerun-if-changed=wrapper.h");    println!("cargo:rerun-if-env-changed=MY_LIB_PATH");
    // Link a system library    println!("cargo:rustc-link-lib=mylib");    println!("cargo:rustc-link-search=/usr/local/lib");
    // Pass a cfg flag to Rust code    let target = env::var("TARGET").unwrap();    if target.contains("linux") {        println!("cargo:rustc-cfg=target_os_linux");    }
    // Set environment variable for downstream crates    println!("cargo:rustc-env=MY_GENERATED_VAR=value");
    // Generate bindings with bindgen    let bindings = bindgen::Builder::default()        .header("wrapper.h")        .generate()        .expect("Unable to generate bindings");
    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());    bindings.write_to_file(out_path.join("bindings.rs")).unwrap();}

`println!` directive	Effect
`cargo:rerun-if-changed=FILE`	Re-run build script if file changes
`cargo:rerun-if-env-changed=VAR`	Re-run if env var changes
`cargo:rustc-link-lib=NAME`	Link library
`cargo:rustc-link-search=PATH`	Add library search path
`cargo:rustc-cfg=FLAG`	Enable `#[cfg(FLAG)]` in code
`cargo:rustc-env=KEY=VAL`	Set `env!("KEY")` at compile time
`cargo:warning=MSG`	Emit build warning

4. Incremental builds and CI caching

yaml

# GitHub Actions with sccache- uses: Swatinem/rust-cache@v2  with:    cache-on-failure: true    shared-key: "release-build"
# Or manual cache- uses: actions/cache@v3  with:    path: |      ~/.cargo/registry/index/      ~/.cargo/registry/cache/      ~/.cargo/git/db/      target/    key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}

# GitHub Actions with sccache- uses: Swatinem/rust-cache@v2  with:    cache-on-failure: true    shared-key: "release-build"
# Or manual cache- uses: actions/cache@v3  with:    path: |      ~/.cargo/registry/index/      ~/.cargo/registry/cache/      ~/.cargo/git/db/      target/    key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}

bash

# Warm cache locallycargo fetch                    # Download all deps without buildingcargo build --tests            # Build everything including test bins
# Check if incremental hurts release builds (it often does)[profile.release]incremental = false            # Default; leave false for release

# Warm cache locallycargo fetch                    # Download all deps without buildingcargo build --tests            # Build everything including test bins
# Check if incremental hurts release builds (it often does)[profile.release]incremental = false            # Default; leave false for release

5. cargo nextest (faster test runner)

bash

# Installcargo install cargo-nextest
# Run tests (parallel by default, better output)cargo nextest run
# Run with specific filtercargo nextest run test_name_pattern
# List tests without runningcargo nextest list
# Use in CI (JUnit output)cargo nextest run --profile ci

# Installcargo install cargo-nextest
# Run tests (parallel by default, better output)cargo nextest run
# Run with specific filtercargo nextest run test_name_pattern
# List tests without runningcargo nextest list
# Use in CI (JUnit output)cargo nextest run --profile ci

nextest.toml:

toml

[profile.ci]fail-fast = falsetest-threads = "num-cpus"retries = { backoff = "exponential", count = 2, delay = "1s" }
[profile.default]test-threads = "num-cpus"

[profile.ci]fail-fast = falsetest-threads = "num-cpus"retries = { backoff = "exponential", count = 2, delay = "1s" }
[profile.default]test-threads = "num-cpus"

6. Dependency management and auditing

bash

# Check for security advisoriescargo install cargo-auditcargo audit
# Deny specific licenses, duplicates, advisoriescargo install cargo-denycargo deny check
# Check for unused dependenciescargo install cargo-machetecargo machete
# Update dependenciescargo update                    # Update to compatible versionscargo update -p serde           # Update single packagecargo upgrade                   # Update to latest (cargo-edit)

# Check for security advisoriescargo install cargo-auditcargo audit
# Deny specific licenses, duplicates, advisoriescargo install cargo-denycargo deny check
# Check for unused dependenciescargo install cargo-machetecargo machete
# Update dependenciescargo update                    # Update to compatible versionscargo update -p serde           # Update single packagecargo upgrade                   # Update to latest (cargo-edit)

deny.toml:

toml

[licenses]allow = ["MIT", "Apache-2.0", "BSD-2-Clause", "BSD-3-Clause"]deny = ["GPL-2.0", "AGPL-3.0"]
[bans]multiple-versions = "warn"deny = [{ name = "openssl", reason = "Use rustls instead" }]
[advisories]ignore = []  # List advisory IDs to ignore

[licenses]allow = ["MIT", "Apache-2.0", "BSD-2-Clause", "BSD-3-Clause"]deny = ["GPL-2.0", "AGPL-3.0"]
[bans]multiple-versions = "warn"deny = [{ name = "openssl", reason = "Use rustls instead" }]
[advisories]ignore = []  # List advisory IDs to ignore

7. Useful cargo commands

bash

# Build only specific binarycargo build --bin myapp
# Build only specific examplecargo build --example myexample
# Run with argumentscargo run -- --flag arg1 arg2
# Expand macros (for debugging proc macros)cargo install cargo-expandcargo expand module::path
# Tree of dependenciescargo treecargo tree --duplicates      # Show crates with multiple versionscargo tree -i serde          # Who depends on serde?
# Cargo.toml metadatacargo metadata --format-version 1 | jq '.packages[].name'

# Build only specific binarycargo build --bin myapp
# Build only specific examplecargo build --example myexample
# Run with argumentscargo run -- --flag arg1 arg2
# Expand macros (for debugging proc macros)cargo install cargo-expandcargo expand module::path
# Tree of dependenciescargo treecargo tree --duplicates      # Show crates with multiple versionscargo tree -i serde          # Who depends on serde?
# Cargo.toml metadatacargo metadata --format-version 1 | jq '.packages[].name'

For workspace patterns and dependency resolution details, see references/workspace-patterns.md [blocked].

Related skills

Use skills/rust/rustc-basics for compiler flags and profile configuration
Use skills/rust/rust-debugging for debugging Cargo-built binaries
Use skills/rust/rust-ffi for build.rs with C library bindings
Use skills/build-systems/cmake when integrating Rust into a CMake build

Source and attribution

Source:mohitmishra786/low-level-dev-skillsinskills/rust/cargo-workflowsat commitbdc5847

License: No license

Content belongs to its original authors. SourceWeft indexes it from a public repository.

Report or request removal

Cargo Workflows

Cargo Workflows

Purpose

Triggers

Workflow

1. Workspace setup

2. Feature flags

3. Build scripts (build.rs)

4. Incremental builds and CI caching

5. cargo nextest (faster test runner)

6. Dependency management and auditing

7. Useful cargo commands

Related skills

Source and attribution

More from mohitmishra786/low-level-dev-skills

Zig Debugging

Simd Intrinsics

Zig Cross

Rustc Basics

Zig Cinterop

Zig Build System

More in Software Development

Playground

M5 Onboard

Cardputer Buddy

Web Design Guidelines

Vercel React Native Skills

Vercel React Best Practices