> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt.

# Rust configuration

> Configuration options for the Fern Rust SDK.

You can customize the behavior of the Rust SDK generator in `generators.yml`:

**`generators.yml`**

```yaml {6-15} title="generators.yml"
groups:
  rust-sdk:
    generators:
      - name: fern-rust-sdk
        version: 0.47.8
        config:
          clientClassName: YourClientName
          crateName: your-crate-name
          crateVersion: "1.0.0"
          dateTimeType: "offset"
          environmentEnumName: YourEnvironment
          enableWireTests: true
```

**`clientClassName`** `string`

The name of the generated client struct. This allows you to customize the struct name that users will instantiate when using your SDK.

---

**`crateName`** `string`

The name of the generated Rust crate. This is used in `Cargo.toml` and determines how users will add your SDK as a dependency.

---

**`crateVersion`** `string`

The version of the generated crate. This is used in `Cargo.toml` for publishing to crates.io.

---

**`dateTimeType`** `'offset' | 'utc'` — default: offset

Determines how timezone information is handled:

* `offset`: Uses `DateTime<FixedOffset>` to preserve the original timezone from API responses
* `utc`: Uses `DateTime<Utc>` to normalize all datetimes to UTC regardless of their original timezone

Both options accept any datetime format and assume UTC if no timezone is provided in the datetime string.

---

**`environmentEnumName`** `string`

The name of the generated environment enum. This allows you to customize the enum name that defines your API environments (such as production, staging, development).

---

**`enableWebsockets`** `boolean` — default: false

Enable generation of [WebSocket clients](/learn/sdks/deep-dives/websocket-clients) for APIs with WebSocket channels.

---

**`enableWireTests`** `boolean` — default: false

When enabled, generates [mock server (wire) tests](/learn/sdks/deep-dives/testing#mock-server-tests) to verify that the SDK sends the correct HTTP requests and correctly handles responses per the API spec.

---

**`generateExamples`** `boolean` — default: true

When enabled, generates code examples in the README and reference documentation.

---

**`maxRetries`** `number`

The default number of retries for failed requests. When not set, the generated SDK defaults to 3 retries. SDK users can still override this per-request via request options.

---

**`respectOptionalRequestBody`** `boolean` — default: false

Lets callers omit the request body on endpoints with an optional request body. The method takes the body as an `Option`, and a call that passes `None` sends no body and no `Content-Type` header, instead of an empty JSON object (`{}`). Enable this when your API treats a missing body differently from an empty one.

Only applies to request bodies declared as a single named type that the endpoint takes on its own. Required bodies, bodies folded into a request wrapper, and inlined request properties are unaffected.

---

### Package metadata

Configure metadata for publishing to crates.io:

**`generators.yml`**

```yaml title="generators.yml"
config:
  packageDescription: "SDK for the Plant Store API"
  packageLicense: "MIT"
  packageRepository: "https://github.com/your-org/your-sdk"
  packageDocumentation: "https://docs.example.com"
```

**`packageDescription`** `string`

A description of the crate for crates.io. This appears in the crate's metadata and search results.

---

**`packageLicense`** `string`

The license identifier for the crate (e.g., "MIT", "Apache-2.0").

---

**`packageLicenseFile`** `string`

Path to a custom license file (e.g., `LICENSE.md`). When set, uses `license-file` instead of `license` in `Cargo.toml`. This is useful when your license isn't a standard Software Package Data Exchange (SPDX) identifier.

---

**`packageRepository`** `string`

The URL of the crate's source repository.

---

**`packageDocumentation`** `string`

The URL of the crate's documentation.

---

### Dependencies

Add custom dependencies to your generated SDK:

**`generators.yml`**

```yaml title="generators.yml"
config:
  extraDependencies:
    tokio: "1.0"
    serde_json: "1.0"
  extraDevDependencies:
    mockall: "0.11"
```

**`extraDependencies`** `object`

Additional dependencies to include in the generated `Cargo.toml`. Specify as a map of crate names to version requirements. You can also specify full dependency specifications with features and default features:

**`generators.yml`**

```yaml title="generators.yml"
config:
  extraDependencies:
    reqwest:
      version: "0.12"
      defaultFeatures: true
```

**`generators.yml`**

```yaml title="generators.yml"
config:
  extraDependencies:
    reqwest:
      version: "0.12"
      features: ["rustls-tls"]
```

---

**`extraDevDependencies`** `object`

Additional dev dependencies to include in the generated `Cargo.toml`. These are only used during development and testing.

---

> Configuration options for the Fern Rust SDK.