/rust-patterns

Cargo and Workspace Patterns

Use this recipe when creating a new Rust project, refactoring into a workspace, or editing Cargo.toml.

New Binary Crate

[package]
name = "service-name"
version = "0.1.0"
edition = "2024"
rust-version = "1.90"
license = "MIT OR Apache-2.0"
publish = false

[dependencies]
tokio = { version = "1", features = ["rt-multi-thread", "macros", "signal", "sync", "time"] }
serde = { version = "1", features = ["derive"] }
serde_json = "1"
thiserror = "2"
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt", "json"] }

Use rust-version = "1.90" as this skill's default floor for new projects (see the baseline in SKILL.md). Drop to 1.85 only when bare Rust 2024 compatibility is the explicit MSRV requirement, and prefer a current stable toolchain when no MSRV constraint exists.

rust-toolchain.toml

Use a floating stable channel for normal greenfield development:

[toolchain]
channel = "stable"
components = ["rustfmt", "clippy"]

Use an exact pin only when reproducibility matters more than automatic patch updates:

[toolchain]
channel = "1.95.0"
components = ["rustfmt", "clippy"]

When pinning to a concrete version, verify it is still the intended current or supported version before generating the file.

Virtual Workspace

For repositories with more than one crate:

[workspace]
resolver = "3"
members = ["crates/*"]

[workspace.package]
edition = "2024"
rust-version = "1.90"
license = "MIT OR Apache-2.0"
publish = false

[workspace.dependencies]
serde = { version = "1", features = ["derive"] }
serde_json = "1"
thiserror = "2"
tokio = { version = "1", features = ["rt-multi-thread", "macros", "signal", "sync", "time"] }
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["env-filter", "fmt", "json"] }

[workspace.lints.rust]
warnings = "deny"
unsafe_code = "forbid"

[workspace.lints.clippy]
unwrap_used = "warn"
expect_used = "warn"
panic = "warn"
print_stdout = "warn"
uninlined_format_args = "warn"
missing_errors_doc = "warn"

Rust 2024 implies resolver 3 for normal packages, but virtual workspaces should set resolver = "3" explicitly.

Member Crate

[package]
name = "my-core"
version = "0.1.0"
edition.workspace = true
rust-version.workspace = true
license.workspace = true
publish.workspace = true

[dependencies]
serde.workspace = true
thiserror.workspace = true
tracing.workspace = true

[lints]
workspace = true

Release Profiles

For deployable binary crates:

[profile.release]
strip = "symbols"
lto = "thin"
codegen-units = 1
panic = "abort"

Guidance:

• Prefer lto = "thin" before full LTO unless maximum size/performance is required.
• Use panic = "abort" only for binaries where unwinding is not required.
• Avoid forcing release profile choices in libraries.

Feature Flags

Keep feature names descriptive and additive:

[features]
default = []
otlp = ["dep:opentelemetry", "dep:opentelemetry_sdk", "dep:opentelemetry-otlp", "dep:tracing-opentelemetry"]
azure = ["dep:azure_identity"]  # azure_identity reached GA 1.0.0 on 2026-05-12 (Azure SDK for Rust)

Rules:

• Features should not silently disable behavior.
• Prefer optional dependencies behind explicit features for telemetry, cloud SDKs, databases, and transport integrations.
• Do not expose feature names like use_foo or with_bar; use the capability name.