[Identity] Adjust IMDS retry backoff

This better aligns with other languages.

Signed-off-by: Paul Van Eck <paulvaneck@microsoft.com>

Author: pvaneck

sdk/identity/azure-identity/BREAKING_CHANGES.md

@@ -1,5 +1,17 @@
 # Breaking Changes
 
+## 1.16.0
+
+### Behavioral change to `ManagedIdentityCredential` in IMDS managed identity scenarios
+
+As of `azure-identity` 1.16.0, `ManagedIdentityCredential` makes a minor change to the retry behavior in environments where Instance Metadata Service (IMDS) managed identity is used. The retry backoff factor for IMDS requests was reduced to `0.8` from `2` to prevent excessive delays during retries and to improve responsiveness. This change might affect workloads that rely on the previous retry behavior.
+
+If retry settings need to be customized for IMDS managed identity scenarios, users can pass in `RetryPolicy` parameters noted in the [Azure Core Client library developer reference](https://github.com/Azure/azure-sdk-for-python/blob/main/sdk/core/azure-core/CLIENT_LIBRARY_DEVELOPER.md#available-policies) to the `ManagedIdentityCredential` constructor. For example:
+
+```python
+credential = ManagedIdentityCredential(retry_connect=8, retry_backoff_factor=2)
+```
+
 ## 1.11.0
 
 ### Behavioral change to credential types supporting multi-tenant authentication

sdk/identity/azure-identity/CHANGELOG.md

@@ -1,11 +1,13 @@
 # Release History
 
-## 1.16.0b3 (Unreleased)
+## 1.16.0 (Unreleased)
 
 ### Features Added
 
 ### Breaking Changes
 
+- For IMDS requests in `ManagedIdentityCredential`, the retry backoff factor was reduced from 2 to 0.8 in order to avoid excessive retry delays. This change might potentially affect workloads that rely on the previous retry behavior. See [BREAKING_CHANGES.md](https://github.com/Azure/azure-sdk-for-python/blob/main/sdk/identity/azure-identity/BREAKING_CHANGES.md).
+
 ### Bugs Fixed
 
 ### Other Changes

sdk/identity/azure-identity/azure/identity/_credentials/imds.py

@@ -21,8 +21,8 @@
 
 PIPELINE_SETTINGS = {
     "connection_timeout": 2,
-    "retry_backoff_factor": 2,
-    "retry_backoff_max": 60,
+    # Five retries, with each retry sleeping for [0.0s, 1.6s, 3.2s, 6.4s, 12.8s] between attempts.
+    "retry_backoff_factor": 0.8,
     "retry_on_status_codes": [404, 410, 429] + list(range(500, 600)),
     "retry_status": 5,
     "retry_total": 5,

sdk/identity/azure-identity/azure/identity/_version.py

@@ -2,4 +2,4 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License.
 # ------------------------------------
-VERSION = "1.16.0b3"
+VERSION = "1.16.0"