azure-identity-rust — Claude Code skill: Azure auth from Rust

---
name: azure-identity-rust
description: |
  Azure Identity library for Rust. Microsoft Entra ID authentication for all Azure SDK clients.
  Triggers: "azure identity rust", "DeveloperToolsCredential", "authentication rust", "managed identity rust", "credential rust", "Entra ID rust".
license: MIT
metadata:
  author: Microsoft
  package: azure_identity
---

# Azure Identity library for Rust

Microsoft Entra ID authentication for Azure SDK clients.

Use this skill when:

- An app needs to authenticate to Azure services from Rust
- You need `DeveloperToolsCredential` for local development
- You need `ManagedIdentityCredential` for Azure-hosted workloads
- You need service principal auth with secret or certificate

> **IMPORTANT:** Only use official `azure_*` crates published by the [azure-sdk](https://crates.io/users/azure-sdk) crates.io user. Do NOT use the deprecated `azure_sdk_*` crates (MindFlavor/AzureSDKForRust) or community crates. Official crates use underscores in names and none have version 0.21.0.

> **Note:** The Rust SDK does not have `DefaultAzureCredential`. Use `DeveloperToolsCredential` for local development and `ManagedIdentityCredential` for production.

```rust
// Incorrect in Rust: this type does not exist in azure_identity
use azure_identity::DefaultAzureCredential;
```

## Installation

```sh
cargo add azure_identity azure_core tokio
```

> If your code uses `azure_core` types directly, add `azure_core` to `Cargo.toml`. If you only use service-crate re-exports, direct `azure_core` dependency is optional.

## Environment Variables

```bash
AZURE_TENANT_ID=<your-tenant-id>         # Required for service principal auth
AZURE_CLIENT_ID=<your-client-id>         # Required for service principal or user-assigned managed identity
AZURE_CLIENT_SECRET=<your-client-secret> # Required for ClientSecretCredential
```

## Authentication

### DeveloperToolsCredential (Local Development)

Tries Azure CLI then Azure Developer CLI:

```rust
use azure_identity::DeveloperToolsCredential;
use azure_security_keyvault_secrets::SecretClient;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Local dev: DeveloperToolsCredential. Production: use ManagedIdentityCredential.
    let credential = DeveloperToolsCredential::new(None)?;
    let client = SecretClient::new(
        "https://<vault-name>.vault.azure.net/",
        credential.clone(),
        None,
    )?;

    let secret = client.get_secret("secret-name", None).await?.into_model()?;
    println!("Secret: {:?}", secret.value);
    Ok(())
}
```

Ensure you are logged in:

```sh
az login        # Azure CLI
azd auth login  # or Azure Developer CLI
```

| Order | Credential                  | Login Command    |
| ----- | --------------------------- | ---------------- |
| 1     | AzureCliCredential          | `az login`       |
| 2     | AzureDeveloperCliCredential | `azd auth login` |

### ManagedIdentityCredential (Production)

For Azure-hosted resources (VMs, App Service, Functions, AKS):

```rust
use azure_identity::ManagedIdentityCredential;

// System-assigned managed identity
let credential = ManagedIdentityCredential::new(None)?;
```

### ClientSecretCredential (Service Principal)

For CI/CD pipelines and service accounts:

```rust
use azure_identity::ClientSecretCredential;

let credential = ClientSecretCredential::new(
    "<tenant-id>",
    "<client-id>",
    "<client-secret>",
    None,
)?;
```

## Credential Types

| Credential                    | Use Case                               |
| ----------------------------- | -------------------------------------- |
| `DeveloperToolsCredential`    | Local development — tries CLI tools    |
| `ManagedIdentityCredential`   | Azure VMs, App Service, Functions, AKS |
| `WorkloadIdentityCredential`  | Kubernetes workload identity           |
| `ClientSecretCredential`      | Service principal with secret          |
| `ClientCertificateCredential` | Service principal with certificate     |
| `AzureCliCredential`          | Direct Azure CLI auth                  |
| `AzureDeveloperCliCredential` | Direct azd CLI auth                    |
| `AzurePipelinesCredential`    | Azure Pipelines service connection     |
| `ClientAssertionCredential`   | Custom assertions (federated identity) |

## Best Practices

1. **Use `cargo add` to manage dependencies, never edit `Cargo.toml` directly.** Add and remove Rust SDK dependencies with cargo commands instead of manual manifest edits.
2. **Add `azure_core` only when importing `azure_core` types directly.** If your code imports `azure_core::http::Url`, `azure_core::http::RequestContent`, or `azure_core::error::ErrorKind`, include `azure_core`; otherwise a direct dependency is optional.
3. **Use `DeveloperToolsCredential`** for local dev, **`ManagedIdentityCredential`** for production — Rust does not provide a single `DefaultAzureCredential` type
4. **Never hardcode credentials** — use environment variables for service principals
5. **Clone credentials** — pass `credential.clone()` when constructing multiple clients; credentials are `Arc`-wrapped
6. **Reuse clients** — clients are thread-safe; create once, share across tasks
7. **Assign RBAC roles** — ensure the identity has appropriate roles for the target service (e.g., "Key Vault Secrets User" for secret reads)
8. **Run `cargo clippy -- -D warnings`** when the prompt, eval, or CI expects lint-clean output; Rust trajectory graders can fail on style lints even after compiler errors are fixed
9. **Future-proof `#[non_exhaustive]` SDK models** — when constructing SDK model/options structs, end the initializer with `..Default::default()` (add `#[allow(clippy::needless_update)]`) and use a `_` wildcard arm when matching SDK enums, so new service-added fields/variants don't break your build

## Reference Links

| Resource      | Link                                                                              |
| ------------- | --------------------------------------------------------------------------------- |
| API Reference | https://docs.rs/azure_identity/latest/azure_identity                              |
| crates.io     | https://crates.io/crates/azure_identity                                           |
| Source Code   | https://github.com/Azure/azure-sdk-for-rust/tree/main/sdk/identity/azure_identity |