Use getent instead of nslookup for starting scripts (#5)

Co-authored-by: Jin Huang <[email protected]>

Author: amuraru

docker/bin/zookeeperFunctions.sh

@@ -19,8 +19,8 @@ function zkConfig() {
 function zkConnectionString() {
   # If the client service address is not yet available, then return localhost
   set +e
-  nslookup "${CLIENT_HOST}" 2>/dev/null 1>/dev/null
-  if [[ $? -eq 1 ]]; then
+  getent hosts "${CLIENT_HOST}" 2>/dev/null 1>/dev/null
+  if [[ $? -ne 0 ]]; then
     set -e
     echo "localhost:${CLIENT_PORT}"
   else

docker/bin/zookeeperReady.sh

@@ -25,8 +25,8 @@ OK=$(echo ruok | nc 127.0.0.1 $CLIENT_PORT)
 # Check to see if zookeeper service answers
 if [[ "$OK" == "imok" ]]; then
   set +e
-  nslookup $DOMAIN
-  if [[ $? -eq 1 ]]; then
+  getent hosts $DOMAIN
+  if [[ $? -ne 0 ]]; then
     set -e
     echo "There is no active ensemble, skipping readiness probe..."
     exit 0

docker/bin/zookeeperStart.sh

@@ -69,30 +69,27 @@ if [[ -n "$ENVOY_SIDECAR_STATUS" ]]; then
 fi
 set -e
 
-# Determine if there is a ensemble available to join by checking the service domain
+# Determine if there is an ensemble available to join by checking the service domain
 set +e
-nslookup $DOMAIN
-if [[ $? -eq 0 ]]; then
-  ACTIVE_ENSEMBLE=true
-elif nslookup $DOMAIN | grep -q "server can't find $DOMAIN"; then
-   echo "there is no active ensemble"
-   ACTIVE_ENSEMBLE=false
-else
-  # If an nslookup of the headless service domain fails, then there is no
-  # active ensemble yet, but in certain cases nslookup of headless service
+getent hosts $DOMAIN  # This only performs a dns lookup
+if [[ $? -ne 0 ]]; then
+  # If dns lookup of the headless service domain fails, then there is no
+  # active ensemble yet, but in certain cases the dns lookup of headless service
   # takes a while to come up even if there is active ensemble
   ACTIVE_ENSEMBLE=false
   declare -i count=20
   while [[ $count -ge 0 ]]
   do
     sleep 2
     ((count=count-1))
-    nslookup $DOMAIN
+    getent hosts $DOMAIN
     if [[ $? -eq 0 ]]; then
       ACTIVE_ENSEMBLE=true
       break
     fi
   done
+else
+  ACTIVE_ENSEMBLE=true
 fi
 
 if [[ "$ONDISK_MYID_CONFIG" == true && "$ONDISK_DYN_CONFIG" == true ]]; then