Azure/personal/dns warning

lib/common.sh

@@ -134,6 +134,26 @@ is_ip_port_reachable()
     nc -w 3 -z $ip $port > /dev/null 2>&1
 }
 
+#
+# Check if the desired entry is present in /etc/hosts
+#
+is_present_in_etc_hosts() {
+    local ip="$1"
+    local hostname="$2"
+
+    while IFS= read -r entry; do
+        # Check if the line is not commented
+        if ! [[ "$entry" =~ ^[[:space:]]*# ]]; then
+            # Check if corresponding entry for IP and hostname is present
+            if echo "$entry" | grep -qE "^[[:space:]]*$ip[[:space:]]*$hostname"; then
+                return 0
+            fi
+        fi
+    done < /etc/hosts
+
+    return 1
+}
+
 #
 # Blob fqdn to IPv4 adddress.
 # Caller must make sure that it is called only for hostname and not IP address.

src/aznfswatchdog

@@ -333,6 +333,14 @@ while :; do
             continue
         fi
 
+        #
+        # Warn if the desired resolution entry is added in /etc/hosts after mount is success
+        #
+        if is_present_in_etc_hosts "$new_ip" "$l_host"; then
+            wecho "[WARNING] Detected static resolution entry for "$l_host" in /etc/hosts."
+            wecho "[Action Required]: Remove the entry for "$l_host" in /etc/hosts to ensure correctly handling endpoint IP address changes by AZNFS"
+        fi
+
         #
         # If the IP changed for the Blob endpoint, we need to update the DNAT rule.
         # This will take care of migration/failover causing the Blob endpoint IP to change.

src/mountscript.sh

@@ -636,13 +636,25 @@ if ! is_valid_blob_fqdn "$nfs_host"; then
     exit 1
 fi
 
+# Resolve the IP address for the NFS host
 nfs_ip=$(resolve_ipv4 "$nfs_host")
 if [ $? -ne 0 ]; then
     echo "$nfs_ip"
     eecho "Cannot resolve IP address for ${nfs_host}!"
     exit 1
 fi
 
+#
+# Check if the IP-FQDN pair is present in /etc/hosts
+# Fail mount if the hostname entry is present in /etc/hosts
+# 
+if is_present_in_etc_hosts "$nfs_ip" "$nfs_host"; then
+    eecho "Mount failed!"
+    eecho "Detected entry $nfs_ip $nfs_host in /etc/hosts."
+    eecho "[Action Required]: Remove or comment out the entry $nfs_ip $nfs_host in /etc/hosts for MOUNT to work."
+    exit 1
+fi
+
 nfs_dir=$(get_dir_from_share "$1")
 if [ $? -ne 0 ]; then
     echo "$nfs_dir"