tarantool_expand.sh: deploy config read check, config instance number

validation added.

extra/tarantool_expand.sh

@@ -43,7 +43,7 @@ error() {
 }
 
 log() {
-	echo "$prompt_name > $*"
+	echo "$prompt_name: $*"
 }
 
 usage() {
@@ -64,6 +64,12 @@ usage() {
 	exit $1
 }
 
+is_numeric() {
+	num=$1
+	[ $num -eq $num ] 2>/dev/null && [ $num -ge 0 ] 2>/dev/null || \
+		return 1
+}
+
 rollback_instance() {
 	id=$1
 	workdir="${prefix_var}/tarantool$id"
@@ -166,6 +172,10 @@ deploy_current=0
 if [ -f $deploy_cfg ]; then
 	deploy_exists=1
 	deploy_current=`cat $deploy_cfg`
+	[ $? -eq 0 ] || error "failed to read deploy config"
+	# validating instance number
+	is_numeric $deploy_current
+	[ $? -eq 0 ] || error "bad deploy config instance number"
 	# dont' change deploy if it said so in configuration file
 	if [ $deploy_current -eq 0 ]; then
 		log "skipping deploy setup (cancel by config)"
@@ -184,8 +194,8 @@ if [ $act_status -ne 0 ]; then
 fi
 
 # validating instance number
-[ $deploy_count -eq $deploy_count ] 2>/dev/null && [ $deploy_count -gt 0 ] || \
-	error "bad instance number"
+is_numeric $deploy_count
+[ $? -eq 0 ] && [ $deploy_count -gt 0 ] || error "bad instance number"
 
 if [ $deploy_count -le $deploy_current ]; then
 	error "expand only is supported (required instances number $deploy_count" \