Assignment: DNS Round Robin Test

Assignment

Ever since Docker Engine 1.11, we can have multiple containers on a created network respond to the same DNS address
Create a new virtual network (default bridge driver)
Create two containers from elasticsearch:2 image
Research and use --network-alias search when creating them to give them an additional DNS name to respond to
Run alpine nslookup search with --net to see the two containers list for the same DNS name
Run centos curl -s search:9200 with --net multiple times until you see both “name” fields show

Create the network

docker network create dude

Create 2 elastic search containers

docker container run --rm -d --net dude --net-alias search elasticsearch:2

run it 2 times, so we have 2 containers running in the background

docker container ls

Check using nslookup

docker container run --rm -it --net dude alpine nslookup search

We can see that there is 2 dns

Check using curl

docker container run --rm -it --net dude centos curl search:9200

run it multiple times, you can see there are 2 instances of elasticseach that give you response

Here is the asciinema record.