Azure SDK for Rust

Before any data-plane traffic is sent to a Gateway 2.0 endpoint, the driver performs a lightweight HTTP/2 connectivity probe to ensure TCP, TLS, and HTTP/2 reachability. This prevents opaque RNTBD timeouts caused by firewall or network misconfigurations.

Probe Wire Contract

• Method + Path: POST /connectivity-probe
• Request/Response Body: Empty
• Protocol: HTTP/2 is required (no HTTP/1.1 fallback)
• Success (200 OK): Probe enabled, proxy ready.
• Feature Disabled (503 Service Unavailable): Proxy is reachable, but the enableConnectivityProbe flag is OFF. This is treated as a probe failure.
• Failure: Any other status, network failure, or timeout indicates the proxy is unreachable.

Gating Policy

1. Strict Success: Only a 200 OK response counts as success. A 503 fails the probe, causing the driver to stay on Gateway V1.
2. All-or-nothing: If the probe fails, Gateway 2.0 is suppressed for every operation and every region across the entire driver. It is not an operation-by-operation downgrade.
3. Client Opt-out: If gateway_v2_disabled is set to true, the probe is skipped entirely.

If your resource provisioning requires extra steps (like generating a certificate), you can use test-resources-pre.ps1 or test-resources-post.ps1 located in the same directory as your test-resources.json file.

To pass data from a pre-script to the main provisioning script, add entries to the $templateFileParameters hash table. These keys will map directly to the parameters defined in your test-resources.json.

Example Workflow:

1. Pre-script: Generates a certificate and adds it to $templateFileParameters.
2. JSON Template: Defines a parameter (e.g., ConfidentialLedgerPrincipalPEM) that receives the value from the pre-script.

# Inside test-resources-pre.ps1
$templateFileParameters['ConfidentialLedgerPrincipalPEM'] = $certValue

// Inside test-resources.json
"parameters": {
  "ConfidentialLedgerPrincipalPEM": {
    "type": "string"
  }
}

When using the cross-region hedging strategy, the driver provides HedgeDiagnostics to allow for observability into how the race between the primary and alternate regions was resolved.

Unlike the .NET SDK, the Rust implementation always attaches the full HedgeDiagnostics whenever a hedging strategy was active (i.e., should_hedge() returned true and execute_hedged() was entered), even if the primary region wins immediately.

DiagnosticsContext::hedge_diagnostics will be None if:

• No AvailabilityStrategy was resolved.
• should_hedge() returned false (e.g., insufficient regions or unsupported ResourceType).
• The strategy short-circuited before spawning the primary (e.g., due to cancellation).

To determine if a hedge actually produced the response returned to the caller, do not rely on a boolean; instead, check if the terminal_state is HedgeTerminalState::AlternateWon.

// Accessing diagnostics from the context
if let Some(diagnostics) = context.hedge_diagnostics {
    let was_hedge = matches!(diagnostics.terminal_state(), HedgeTerminalState::AlternateWon);
    let winner = diagnostics.response_region();
    // ...
}

All Azure.ClientGenerator.Core decorators support an optional scope parameter as their final argument. This allows you to target specific language emitters or exclude them.

Scope Syntax

@decoratorName(/* decorator-specific params */, scope?: string)

Supported Language Identifiers

• "csharp" - C#/.NET
• "python" - Python
• "java" - Java
• "javascript" - TypeScript/JavaScript
• "go" - Go
• "rust" - Rust

Scope Patterns

Target Specific Languages

// Single language
@@clientName(Foo, "Bar", "python")

// Multiple languages (comma-separated)
@@clientName(Foo, "Bar", "python, javascript")

Exclude Languages (Negation)

Use the ! prefix to exclude languages.

// All languages EXCEPT C#
@@clientName(Foo, "Bar", "!csharp")

// All languages EXCEPT python and go
@@clientName(Foo, "Bar", "!python, !go")

// Single language
@@clientName(Foo, "Bar", "python")

// Multiple languages
@@clientName(Foo, "Bar", "python, javascript")

// Exclude
@@clientName(Foo, "Bar", "!csharp")