Azure · mrm9084 · Apr 13, 2026 · Jan 29, 2026 · Jan 29, 2026 · Jan 29, 2026
@@ -4,6 +4,8 @@
 
 ### Features Added
 
+- Added `startup-timeout` configuration option that enables automatic retry with backoff when transient failures occur during application startup. The provider will continue retrying until the timeout expires (default: 100 seconds).
+
 ### Breaking Changes
 
 ### Bugs Fixed

@@ -107,6 +107,16 @@ String findOriginForEndpoint(String endpoint) {
         return endpoint;
     }
 
+    /**
+     * Gets the duration in milliseconds until the next client becomes available for the specified store.
+     * 
+     * @param originEndpoint the origin configuration store endpoint
+     * @return duration in milliseconds until next client is available, or 0 if one is available now
+     */
+    long getMillisUntilNextClientAvailable(String originEndpoint) {
+        return CONNECTIONS.get(originEndpoint).getMillisUntilNextClientAvailable();
+    }
+
     /**
      * Updates the sync token for a specific replica endpoint.
      * 

@@ -128,7 +128,7 @@ public List<AzureAppConfigDataResource> resolveProfileSpecific(
 
         for (ConfigStore store : properties.getStores()) {
             locations.add(
-                new AzureAppConfigDataResource(properties.isEnabled(), store, profiles, START_UP.get(), properties.getRefreshInterval()));
+                new AzureAppConfigDataResource(properties.isEnabled(), store, profiles, START_UP.get(), properties.getRefreshInterval(), properties.getStartupTimeout()));
         }
         START_UP.set(false);
         return locations;

@@ -47,16 +47,21 @@ public class AzureAppConfigDataResource extends ConfigDataResource {
     /** The interval at which configuration should be refreshed from the store. */
     private final Duration refreshInterval;
 
+    /** The timeout duration for retry attempts during startup. */
+    private final Duration startupTimeout;
+
     /**
      * Constructs a new AzureAppConfigDataResource with the specified configuration store settings.
      * 
+     * @param appConfigEnabled true if Azure App Configuration is globally enabled
      * @param configStore the configuration store settings containing endpoint, selectors, and other options
      * @param profiles the Spring Boot profiles for conditional configuration loading
      * @param startup true if this is a startup load operation, false if it is a refresh operation
      * @param refreshInterval the interval at which configuration should be refreshed
+     * @param startupTimeout the timeout duration for retry attempts during startup
      */
     AzureAppConfigDataResource(boolean appConfigEnabled, ConfigStore configStore, Profiles profiles, boolean startup,
-        Duration refreshInterval) {
+        Duration refreshInterval, Duration startupTimeout) {
         this.configStoreEnabled = appConfigEnabled && configStore.isEnabled();
         this.endpoint = configStore.getEndpoint();
         this.selects = configStore.getSelects();
@@ -66,6 +71,7 @@ public class AzureAppConfigDataResource extends ConfigDataResource {
         this.profiles = profiles;
         this.isRefresh = !startup;
         this.refreshInterval = refreshInterval;
+        this.startupTimeout = startupTimeout;
     }
 
     /**
@@ -148,4 +154,13 @@ public boolean isRefresh() {
     public Duration getRefreshInterval() {
         return refreshInterval;
     }
+
+    /**
+     * Gets the timeout duration for retry attempts during startup.
+     * 
+     * @return the startup timeout duration
+     */
+    public Duration getStartupTimeout() {
+        return startupTimeout;
+    }
 }
@@ -222,6 +222,51 @@ void backoffClient(String endpoint) {
         autoFailoverClients.get(endpoint).updateBackoffEndTime(Instant.now().plusNanos(backoffTime));
     }
 
+    /**
+     * Gets the duration in milliseconds until the next client becomes available (exits backoff).
+     * Returns 0 if a client is already available, or the minimum wait time if all clients are in backoff.
+     * 
+     * @return duration in milliseconds until next client is available, or 0 if one is available now
+     */
+    long getMillisUntilNextClientAvailable() {
+        Instant now = Instant.now();
+        Instant earliestAvailable = Instant.MAX;
+
+        // Check configured clients
+        if (clients != null) {
+            for (AppConfigurationReplicaClient client : clients) {
+                Instant backoffEnd = client.getBackoffEndTime();
+                if (!backoffEnd.isAfter(now)) {
+                    return 0; // Client available now
+                }
+                if (backoffEnd.isBefore(earliestAvailable)) {
+                    earliestAvailable = backoffEnd;
+                }
+            }
+        }
+
+        // Check auto-failover clients
+        for (AppConfigurationReplicaClient client : autoFailoverClients.values()) {
+            Instant backoffEnd = client.getBackoffEndTime();
+            if (!backoffEnd.isAfter(now)) {
+                return 0; // Client available now
+            }
+            if (backoffEnd.isBefore(earliestAvailable)) {
+                earliestAvailable = backoffEnd;
+            }
+        }
+
+        // If no clients were found or no backoff times were set, avoid calling toEpochMilli on Instant.MAX.
+        if (Instant.MAX.equals(earliestAvailable)) {
+            // No clients are currently tracked; treat as no wait required.
+            return 0L;
+        }
+
+        long millisUntilNext = earliestAvailable.toEpochMilli() - now.toEpochMilli();
+        // Ensure we never return a negative duration, even in the presence of clock skew.
+        return Math.max(millisUntilNext, 0L);
+    }
+
     /**
      * Updates the synchronization token for the specified client endpoint.
      * 

@@ -37,9 +37,12 @@ public class AppConfigurationProperties {
     private Duration refreshInterval;
 
     /**
-     * Returns whether Azure App Configuration is enabled.
-     *
-     * @return {@code true} if enabled, {@code false} otherwise
+     * The timeout duration for retry attempts during startup.
+     */
+    private Duration startupTimeout = Duration.ofSeconds(100);
+
+    /**
+     * @return the enabled
      */
     public boolean isEnabled() {
         return enabled;
@@ -91,10 +94,22 @@ public void setRefreshInterval(Duration refreshInterval) {
     }
 
     /**
-     * Validates that at least one store is configured with a valid endpoint or
-     * connection string, and that no duplicate endpoints exist.
-     *
-     * @throws IllegalArgumentException if validation fails or duplicate endpoints are found
+     * @return the startupTimeout
+     */
+    public Duration getStartupTimeout() {
+        return startupTimeout;
+    }
+
+    /**
+     * @param startupTimeout the startupTimeout to set
+     */
+    public void setStartupTimeout(Duration startupTimeout) {
+        this.startupTimeout = startupTimeout;
+    }
+
+    /**
+     * Validates at least one store is configured for use, and that they are valid.
+     * @throws IllegalArgumentException when duplicate endpoints are configured
      */
     @PostConstruct
     public void validateAndInit() {
@@ -134,5 +149,12 @@ public void validateAndInit() {
         if (refreshInterval != null) {
             Assert.isTrue(refreshInterval.getSeconds() >= 1, "Minimum refresh interval time is 1 Second.");
         }
+        if (startupTimeout == null) {
+            throw new IllegalArgumentException("startupTimeout cannot be null.");
+        }
+        if (startupTimeout.compareTo(Duration.ofSeconds(30)) < 0
+            || startupTimeout.compareTo(Duration.ofSeconds(600)) > 0) {
+            throw new IllegalArgumentException("startupTimeout must be between 30 and 600 seconds.");
+        }
     }
 }