Docker : Swarm Cluster2023/06/22 |
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Configure Docker Swarm to create Docker Cluster with multiple Docker nodes.
On this example, Configure Swarm Cluster with 3 Docker nodes like follows.
There are 2 roles on Swarm Cluster, those are [Manager nodes] and [Worker nodes]. This example shows to set those roles like follows.
-----------+---------------------------+--------------------------+------------
| | |
eth0|10.0.0.51 eth0|10.0.0.52 eth0|10.0.0.53
+----------+-----------+ +-----------+----------+ +-----------+----------+
| [ node01.srv.world ] | | [ node02.srv.world ] | | [ node03.srv.world ] |
| Manager | | Worker | | Worker |
+----------------------+ +----------------------+ +----------------------+
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| [1] | |
| [2] | Disable live-restore feature on all Nodes. (because it can not use live-restore feature on Swarm mode) |
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root@node01:~#
vi /etc/docker/daemon.json # create new
{
"live-restore": false
}
systemctl restart docker |
| [3] | Configure Swarm Cluster on Manager Node. |
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root@node01:~# docker swarm init
Swarm initialized: current node (p8b0irmy3elmj1vrdsonfiv40) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-2lxb5xwdxogw3esn78wahhcw8sj3p47wyan0xlla0vy288ofxb-ew6kbqs3qnj2p2nmqm2hdoa80 10.0.0.51:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
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| [4] | Join in Swarm Cluster on all Worker Nodes. It's OK to run the command which was shown when running swarm init on Manager Node. |
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root@node02:~# docker swarm join \ --token SWMTKN-1-2lxb5xwdxogw3esn78wahhcw8sj3p47wyan0xlla0vy288ofxb-ew6kbqs3qnj2p2nmqm2hdoa80 10.0.0.51:2377 This node joined a swarm as a worker. |
| [5] | Verify with a command [node ls] that worker nodes could join in Cluster normally. |
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root@node01:~# docker node ls ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION p8b0irmy3elmj1vrdsonfiv40 * node01.srv.world Ready Active Leader 20.10.24 pda4o1jnkcka35rup801abljf node02.srv.world Ready Active 20.10.24 bqwt9t82vklehlyrlos7neueq node03.srv.world Ready Active 20.10.24 |
| [6] | After creating Swarm Cluster, configure services the Swarm Cluster provides. For example, create a Nginx container to configure Swarm service. Generally, it is used a container image on a rgistry on all Nodes, but on this example, create container images on each Node to verify settings and accesses for Swarm Cluster. |
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root@node01:~#
vi Dockerfile FROM debian MAINTAINER ServerWorld <admin@srv.world> RUN apt-get update RUN apt-get -y install nginx RUN echo "Nginx on node01" > /var/www/html/index.html EXPOSE 80 CMD ["/usr/sbin/nginx", "-g", "daemon off;"] docker build -t nginx-server:latest . |
| [7] | Configure service on Manager Node. After succeeding to configure service, access to the Manager node's Hostname or IP address to verify it works normally. Access requests to worker nodes are load-balanced with round-robin like follows. |
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root@node01:~# docker images REPOSITORY TAG IMAGE ID CREATED SIZE nginx-server latest 396adbbc737d About a minute ago 160MB debian latest 7e0aa2d69a15 2 weeks ago 72.7MB # create a service with 2 replicas root@node01:~# docker service create --name swarm_cluster --replicas=2 -p 80:80 nginx-server:latest vnj5f8bzgqctnpbo7e21vhx7a overall progress: 2 out of 2 tasks 1/2: running 2/2: running verify: Service converged # show service list root@node01:~# docker service ls ID NAME MODE REPLICAS IMAGE PORTS vnj5f8bzgqct swarm_cluster replicated 2/2 nginx-server:latest *:80->80/tcp # inspect the service root@node01:~# docker service inspect swarm_cluster --pretty ID: vnj5f8bzgqctnpbo7e21vhx7a Name: swarm_cluster Service Mode: Replicated Replicas: 2 Placement: UpdateConfig: Parallelism: 1 On failure: pause Monitoring Period: 5s Max failure ratio: 0 Update order: stop-first RollbackConfig: Parallelism: 1 On failure: pause Monitoring Period: 5s Max failure ratio: 0 Rollback order: stop-first ContainerSpec: Image: nginx-server:latest Init: false Resources: Endpoint Mode: vip Ports: PublishedPort = 80 Protocol = tcp TargetPort = 80 PublishMode = ingress # show service state root@node01:~# docker service ps swarm_cluster ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS i8kqhuro1i0a swarm_cluster.1 nginx-server:latest node02.srv.world Running Running about a minute ago mp2run84lhsi swarm_cluster.2 nginx-server:latest node01.srv.world Running Running about a minute ago # verify it works normally root@node01:~# curl node01.srv.world Nginx on node02 root@node01:~# curl node01.srv.world Nginx on node01 root@node01:~# curl node01.srv.world Nginx on node02 root@node01:~# curl node01.srv.world Nginx on node01 |
| [8] | If you'd like to change the number of replicas, configure like follows. |
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# change replicas to 3 root@node01:~# docker service scale swarm_cluster=3 swarm_cluster scaled to 3 overall progress: 3 out of 3 tasks 1/3: running 2/3: running 3/3: running verify: Service converged root@node01:~# docker service ps swarm_cluster ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS i8kqhuro1i0a swarm_cluster.1 nginx-server:latest node02.srv.world Running Running 2 minutes ago mp2run84lhsi swarm_cluster.2 nginx-server:latest node01.srv.world Running Running 2 minutes ago avioamhacach swarm_cluster.3 nginx-server:latest node03.srv.world Running Running 14 seconds ago # verify accesses root@node01:~# curl node01.srv.world Nginx on node03 root@node01:~# curl node01.srv.world Nginx on node02 root@node01:~# curl node01.srv.world Nginx on node01 |
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