> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/dotandev/envcheck/llms.txt
> Use this file to discover all available pages before exploring further.

# Rust Project

> Environment validation for Rust applications

## Overview

This example demonstrates envcheck configuration for a Rust project. It validates the Rust toolchain, optional environment variables for logging and database connectivity, and required Cargo files.

## Configuration

```yaml .envcheck.yaml theme={null}
version: "1"

tools:
  - name: rustc
    version: ">=1.65.0"
    required: true
  - name: cargo
    required: true

env_vars:
  - name: RUST_LOG
    required: false
  - name: DATABASE_URL
    required: false

files:
  - path: Cargo.toml
    required: true
  - path: src/main.rs
    required: false
  - path: src/lib.rs
    required: false
```

## What This Checks

### Tools

* **rustc >=1.65.0**: Ensures you have a modern Rust compiler with the 2021 edition features
* **cargo**: Validates Rust's package manager and build tool is available

### Environment Variables

* **RUST\_LOG** (optional): Controls logging verbosity for applications using `env_logger` or `tracing`
* **DATABASE\_URL** (optional): Connection string for database access when using SQLx or Diesel

### Files

* **Cargo.toml**: Project manifest - required for all Rust projects
* **src/main.rs** (optional): Binary entry point - checked for application projects
* **src/lib.rs** (optional): Library entry point - checked for library crates

## Expected Output

<CodeGroup>
  ```bash Success theme={null}
  $ envcheck

  ✓ Tools
    ✓ rustc: 1.75.0 (>= 1.65.0)
    ✓ cargo: installed

  ✓ Environment Variables
    ✓ RUST_LOG: info
    ✓ DATABASE_URL: ***

  ✓ Files
    ✓ Cargo.toml: exists
    ✓ src/main.rs: exists
    ✓ src/lib.rs: not found (optional)

  All checks passed!
  ```

  ```bash Missing Toolchain theme={null}
  $ envcheck

  ✗ Tools
    ✗ rustc: 1.60.0 (expected >= 1.65.0)
    ✓ cargo: installed

  ✓ Environment Variables
    (all optional)

  ✗ Files
    ✗ Cargo.toml: not found
    ✓ src/main.rs: not found (optional)
    ✓ src/lib.rs: not found (optional)

  Checks failed!
  ```
</CodeGroup>

## Tips for Rust Projects

<Tip>
  Update your Rust toolchain easily with `rustup update`. Use `rustup show` to see your current installed versions.
</Tip>

<Warning>
  If DATABASE\_URL is required for compile-time query checking with SQLx, mark it as `required: true` and set it even in development.
</Warning>

<Info>
  The configuration checks for both `src/main.rs` and `src/lib.rs` as optional, making it suitable for both binary and library projects.
</Info>

## Common Variations

### Web API with Actix/Axum

Add web framework requirements:

```yaml theme={null}
env_vars:
  - name: RUST_LOG
    required: true
    pattern: "^(trace|debug|info|warn|error)$"
  - name: DATABASE_URL
    required: true
  - name: HOST
    required: false
  - name: PORT
    required: false

ports:
  - 8080

files:
  - path: Cargo.toml
    required: true
  - path: src/main.rs
    required: true
```

### SQLx Database Project

Ensure SQLx compile-time checks work:

```yaml theme={null}
tools:
  - name: rustc
    version: ">=1.65.0"
    required: true
  - name: cargo
    required: true
  - name: sqlx-cli
    required: true

env_vars:
  - name: DATABASE_URL
    required: true  # Required for compile-time query verification

files:
  - path: migrations
    required: true
  - path: .sqlx
    required: false
```

### Embedded/No-Std Project

Validate cross-compilation toolchain:

```yaml theme={null}
tools:
  - name: rustc
    version: ">=1.65.0"
    required: true
  - name: cargo
    required: true
  - name: arm-none-eabi-gcc
    required: true

files:
  - path: Cargo.toml
    required: true
  - path: memory.x
    required: true
  - path: .cargo/config.toml
    required: true
```

### Workspace Setup

For multi-crate workspaces:

```yaml theme={null}
files:
  - path: Cargo.toml
    required: true
  - path: Cargo.lock
    required: true

tools:
  - name: rustc
    version: ">=1.65.0"
    required: true
  - name: cargo
    required: true
  - name: cargo-workspaces
    required: false
```

### WASM Target

Validate WebAssembly toolchain:

```yaml theme={null}
tools:
  - name: rustc
    version: ">=1.65.0"
    required: true
  - name: cargo
    required: true
  - name: wasm-pack
    required: true

files:
  - path: Cargo.toml
    required: true
  - path: src/lib.rs
    required: true
```

## Rust-Specific Considerations

### Logging Levels

RUST\_LOG accepts various formats:

* Simple: `info`, `debug`, `trace`
* Module-specific: `my_crate=debug,hyper=info`
* Complex filters: `warn,my_crate::module=trace`

### Database URL Format

Common DATABASE\_URL patterns:

* PostgreSQL: `postgres://user:pass@localhost/db`
* MySQL: `mysql://user:pass@localhost/db`
* SQLite: `sqlite://path/to/db.sqlite` or `sqlite::memory:`

### Cargo Configuration

Consider checking `.cargo/config.toml` for projects with custom build configurations, target specifications, or registry settings.

## Learn More

* [Tools Validator](/configuration/tools) - Rust toolchain and cargo tools
* [Environment Variables](/configuration/environment-variables) - Runtime configuration
* [File Validator](/configuration/files) - Project structure validation
* [Port Checker](/configuration/ports) - Service port management