Docker Swarm With Single Master

What is swarm?

Docker swarm is the concept which is use to do cluster management in dcockr. swarm contain multiple docker host know as nodes. Node can be a manager or worker.

Manager --> Manage swarm services 

Worker --> Fasilitate to run swarm services

How to configure docker swarm?

We need to have 3 servers

1--Master Node

2--Worker Node

Master --> 192.168.1.131

Worker-1 --> 192.168.1.132

Worker-2 --> 192.168.1.133

Step 1

Install and enable docker service in each servers

yum install docker-ce docker-ce-cli containerd.io

systemctl enable docker

systemctl start docker

Step 2

Configure docker swarm in manager node

docker swarm init --advertise-addr 192.168.1.131

Step 3

Add Worker Node to docker swarm. You will get join token for worker nodes from above command.

docker swarm join --token SWMTKN-1-4756c3muztsup58wb0hc8ewwturxwmp3s40gbmx3ts9m5dmbwr-dpt2duvjtsayw9w3l73q49r1e 192.168.1.131:2377

To verify the docker nodes

docker node ls

Step 4

Create Docker Service

Here I am using nginx docker image to create docker image. Initially I am creating three docker-nginx containers and expose port 80 and 443 for out side.

docker service create --replicas 3 -p 80:80 -p 443:443 --hostname=docker-nginx.local --name docker-nginx nginx

To verify the docker service 

docker service ls

Scale the service

docker service scale vqnerzh63o45=4

You can type manager IP to load the webserver default page.

http://192.168.1.131/