minor changes in script and dockerfile

Author: vijeyash1

dockerfiles/migration/Dockerfile

@@ -11,6 +11,7 @@ RUN chmod +x /workspace/script/wait-for-clickhouse.sh
 # Use distroless as minimal base image to package the manager binary
 # Refer to https://github.com/GoogleContainerTools/distroless for more details
 FROM golang:alpine
+RUN apk add --no-cache netcat-openbsd
 WORKDIR /
 COPY --from=builder /workspace/migration .
 COPY --from=builder /workspace/sql /sql

script/wait-for-clickhouse.sh

@@ -7,7 +7,7 @@ MAX_RETRIES=60
 
 retry_count=0
 while [ $retry_count -lt $MAX_RETRIES ]; do
-  if clickhouse-client --host $CLICKHOUSE_HOST --port $CLICKHOUSE_PORT --query "SELECT 1"; then
+  if nc -z -v -w5 $CLICKHOUSE_HOST $CLICKHOUSE_PORT; then
     echo "ClickHouse is ready!"
     exit 0
   else