flyrain commented on code in PR #3113:
URL: https://github.com/apache/polaris/pull/3113#discussion_r2575839659


##########
polaris-core/src/main/java/org/apache/polaris/core/config/FeatureConfiguration.java:
##########
@@ -438,4 +438,47 @@ public static void enforceFeatureEnabledOrThrow(
               "If set to true (default), allow credential vending for external 
catalogs. Note this requires ALLOW_EXTERNAL_CATALOG_CREDENTIAL_VENDING to be 
true first.")
           .defaultValue(true)
           .buildFeatureConfiguration();
+
+  public static final FeatureConfiguration<Integer> CLOUD_API_TIMEOUT_MILLIS =

Review Comment:
   `CLOUD_API_TIMEOUT_MILLIS` may over-communicate its scope. Would a more 
precise name like `STORAGE_API_TIMEOUT_MILLIS` or even 
`AZURE_STORAGE_API_TIMEOUT_MILLIS` be clearer? 
   
   If s3/GCS/MinIO doesn't have similar configuration or cannot be applied with 
the same timeout, I'd suggest to have a prefix `AZURE_` to make it clear. 
   



##########
polaris-core/src/main/java/org/apache/polaris/core/storage/azure/AzureCredentialsStorageIntegration.java:
##########
@@ -312,16 +318,103 @@ private void validateAccountAndContainer(
         });
   }
 
-  private AccessToken getAccessToken(String tenantId) {
+  /**
+   * Fetches an Azure AD access token with timeout and retry logic to handle 
transient failures.
+   *
+   * <p>This access token is used internally to obtain a user delegation key 
from Azure Storage,
+   * which is then used to generate SAS tokens for client credential vending.
+   *
+   * <p>This method implements a defensive strategy against slow or failing 
cloud provider requests:
+   *
+   * <ul>
+   *   <li>Per-attempt timeout (configurable via CLOUD_API_TIMEOUT_MILLIS, 
default 15000ms)
+   *   <li>Exponential backoff retry (configurable count and initial delay via 
CLOUD_API_RETRY_COUNT
+   *       and CLOUD_API_RETRY_DELAY_MILLIS, defaults: 3 attempts starting at 
2000ms)
+   *   <li>Jitter to prevent thundering herd (configurable via 
CLOUD_API_RETRY_JITTER_FACTOR,
+   *       default 0.5 = 50%%)
+   * </ul>
+   *
+   * @param realmConfig the realm configuration to get timeout and retry 
settings
+   * @param tenantId the Azure tenant ID
+   * @return the access token
+   * @throws RuntimeException if token fetch fails after all retries or times 
out
+   */
+  private AccessToken getAccessToken(RealmConfig realmConfig, String tenantId) 
{
+    int timeoutMillis = realmConfig.getConfig(CLOUD_API_TIMEOUT_MILLIS);
+    int retryCount = realmConfig.getConfig(CLOUD_API_RETRY_COUNT);
+    int initialDelayMillis = 
realmConfig.getConfig(CLOUD_API_RETRY_DELAY_MILLIS);
+    double jitter = realmConfig.getConfig(CLOUD_API_RETRY_JITTER_FACTOR);
+
     String scope = "https://storage.azure.com/.default";;
     AccessToken accessToken =
         defaultAzureCredential
             .getToken(new 
TokenRequestContext().addScopes(scope).setTenantId(tenantId))
+            .timeout(Duration.ofMillis(timeoutMillis))
+            .doOnError(
+                error ->
+                    LOGGER.warn(
+                        "Error fetching Azure access token for tenant {}: {}",
+                        tenantId,
+                        error.getMessage()))

Review Comment:
   Can we log the full stack trace instead of `error.getMessage()` only for 
better debuggability?



##########
polaris-core/src/main/java/org/apache/polaris/core/storage/azure/AzureCredentialsStorageIntegration.java:
##########
@@ -312,16 +318,103 @@ private void validateAccountAndContainer(
         });
   }
 
-  private AccessToken getAccessToken(String tenantId) {
+  /**
+   * Fetches an Azure AD access token with timeout and retry logic to handle 
transient failures.
+   *
+   * <p>This access token is used internally to obtain a user delegation key 
from Azure Storage,
+   * which is then used to generate SAS tokens for client credential vending.
+   *
+   * <p>This method implements a defensive strategy against slow or failing 
cloud provider requests:
+   *
+   * <ul>
+   *   <li>Per-attempt timeout (configurable via CLOUD_API_TIMEOUT_MILLIS, 
default 15000ms)
+   *   <li>Exponential backoff retry (configurable count and initial delay via 
CLOUD_API_RETRY_COUNT
+   *       and CLOUD_API_RETRY_DELAY_MILLIS, defaults: 3 attempts starting at 
2000ms)
+   *   <li>Jitter to prevent thundering herd (configurable via 
CLOUD_API_RETRY_JITTER_FACTOR,
+   *       default 0.5 = 50%%)
+   * </ul>
+   *
+   * @param realmConfig the realm configuration to get timeout and retry 
settings
+   * @param tenantId the Azure tenant ID
+   * @return the access token
+   * @throws RuntimeException if token fetch fails after all retries or times 
out
+   */
+  private AccessToken getAccessToken(RealmConfig realmConfig, String tenantId) 
{
+    int timeoutMillis = realmConfig.getConfig(CLOUD_API_TIMEOUT_MILLIS);
+    int retryCount = realmConfig.getConfig(CLOUD_API_RETRY_COUNT);
+    int initialDelayMillis = 
realmConfig.getConfig(CLOUD_API_RETRY_DELAY_MILLIS);
+    double jitter = realmConfig.getConfig(CLOUD_API_RETRY_JITTER_FACTOR);
+
     String scope = "https://storage.azure.com/.default";;
     AccessToken accessToken =
         defaultAzureCredential
             .getToken(new 
TokenRequestContext().addScopes(scope).setTenantId(tenantId))
+            .timeout(Duration.ofMillis(timeoutMillis))
+            .doOnError(
+                error ->
+                    LOGGER.warn(
+                        "Error fetching Azure access token for tenant {}: {}",
+                        tenantId,
+                        error.getMessage()))
+            .retryWhen(
+                Retry.backoff(retryCount, 
Duration.ofMillis(initialDelayMillis))
+                    .jitter(jitter) // Apply jitter factor to computed delay
+                    .filter(this::isRetriableAzureException)
+                    .doBeforeRetry(
+                        retrySignal ->
+                            LOGGER.info(
+                                "Retrying Azure token fetch for tenant {} 
(attempt {}/{})",
+                                tenantId,
+                                retrySignal.totalRetries() + 1,
+                                retryCount))

Review Comment:
   Should we add 1 to retryCount? Sot it matches the word "attempt" here? The 
total attempt number would be 1 + retryCount:
   ```
   int maxAttempts = retryCount + 1;
   ...
   
   LOGGER.info("Retrying Azure token fetch for tenant {} (attempt {}/{})",
               tenantId,
               retrySignal.totalRetries() + 1,
               maxAttempts);
   ```



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