Azure cloud_init: do not print early error messages

When an Azure instance starts, a few seconds may elapse before its
network interface acquires a DHCP address, and during this time
interval the Azure Wire Server is unreachable. To avoid potentially
misleading log output, do not print error messages if connection to
the server fails at the first attempt.

klib/cloud_azure.c

@@ -43,6 +43,7 @@ typedef struct azure {
     vector extensions;
     struct spinlock lock;
     boolean goalstate_pending;
+    boolean goalstate_print_errors;
     boolean provisioned;
 } *azure;
 
@@ -75,9 +76,11 @@ closure_func_basic(timer_handler, void, az_report_th,
     if (is_ok(s)) {
         az->goalstate_pending = true;
     } else {
-        msg_err("%s error %v", func_ss, s);
+        if (az->goalstate_print_errors)
+            msg_err("%s error %v", func_ss, s);
         timm_dealloc(s);
     }
+    az->goalstate_print_errors = true;
 }
 
 static void az_report_status(azure az)
@@ -563,6 +566,9 @@ boolean azure_cloud_init(heap h)
     spin_lock_init(&az->lock);
     az->container_id_len = az->instance_id_len = 0;
     az->goalstate_pending = az->provisioned = false;
+    /* Do not print error messages if the Azure Wire Server is unreachable just after instance
+     * startup (a few seconds may elapse before the network interface acquires a DHCP address). */
+    az->goalstate_print_errors = false;
     az_status_upload_init(az);
     init_timer(&az->report_timer);
     register_timer(kernel_timers, &az->report_timer, CLOCK_ID_MONOTONIC, seconds(2), false,