To loop through comma separated string, you need to use the combination of for loop and sed. There are few ways you can achieve this.
You can add your business logic inside the do done block as shown in the examples below.
Method 1:
hosts="node1,node2"
for i in $(echo $hosts | sed "s/,/ /g")
do
echo $i
done
Method 2:
variable=node1,node2
for i in ${variable//,/ }
do
echo "$i"
done