Docker Clustering with Swarm in Centos7

Docker Clustering with Swarm in Centos7 is a process of creating a cluster of Docker hosts using the Docker Swarm feature in the CentOS 7 operating system. The Swarm feature is a native clustering and orchestration tool within Docker that enables users to create and manage a cluster of Docker hosts. This process involves setting up a Docker Swarm manager and one or more Docker Swarm nodes, configuring the network and storage for the cluster, and deploying and scaling Docker services across the cluster. The benefits of clustering Docker hosts with Swarm in CentOS 7 include increased scalability, high availability, and load balancing of Docker services, as well as simplified management and deployment of containerized applications.

Installing Docker

mkdir /install-files ; cd /install-files

wget https://yum.dockerproject.org/repo/main/centos/7/Packages/docker-engine-1.13.1-1.el7.centos.x86_64.rpm
wget https://yum.dockerproject.org/repo/main/centos/7/Packages/docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm

Package for docker-engine-selinux

yum install -y policycoreutils-python
rpm -i docker-engine-selinux-1.13.1-1.el7.centos.noarch.rpm

Package for docker-engine

yum install -y libtool-ltdl libseccomp
rpm -i docker-engine-1.13.1-1.el7.centos.x86_64.rpm

Remove rpm packages

rm docker-engine-* -f

Enable systemd service

systemctl enable docker

Start docker

systemctl start docker

Firewalld Enabling Firewall Rules

firewall-cmd --get-active-zones
firewall-cmd --list-all
firewall-cmd --zone=public --add-port=2377/tcp --permanent
firewall-cmd --permanent --add-source=192.168.56.0/24
firewall-cmd --permanent --add-port=2377/tcp
firewall-cmd --permanent --add-port=7946/tcp
firewall-cmd --permanent --add-port=7946/udp
firewall-cmd --permanent --add-port=4789/udp
firewall-cmd --reload

Enable and Restart systemd service

systemctl enable docker;
systemctl restart docker

Docker Cluster Env

docker swarm init --advertise-addr=192.168.56.105

Swarm initialized: current node (b4b79zi3t1mq1572r0iubxdhc) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join \
    --token SWMTKN-1-1wcz7xfyvhewvj3dd4wcbhufw4lub3b1vgpuoybh90myzookbf-4ksxoxrilifb2tmvuligp9krs \
    192.168.56.101:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

To join as a Swarm manager

docker swarm join-token manager

  docker swarm join \
    --token SWMTKN-1-10cqx6yryq5kyfe128m2xhyxzplsc90lzksqggmscv1nfipsbb-bfdbvfhuw9sg8mx2i1a4rkvlv \
    192.168.56.101:2377