Docker : Swarm Cluster2023/04/27 |
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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 (f4ue4qyqktrni5p7nnbr7x6li) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-4gt7zmwrqpof90tytviha4k6u1reci8tjx01kpizbo1z5zjnim-50gkc0zks74gwzlxd2uli2awb 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-1-4gt7zmwrqpof90tytviha4k6u1reci8tjx01kpizbo1z5zjnim-50gkc0zks74gwzlxd2uli2awb 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 f4ue4qyqktrni5p7nnbr7x6li * node01.srv.world Ready Active Leader 20.10.21 fcngtb6my4w7nzy6lj33oujnx node02.srv.world Ready Active 20.10.21 3e27nzgbkaxbrfbgczj5oynyg node03.srv.world Ready Active 20.10.21 |
| [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 ubuntu 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 successing 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 7bda1eb47720 About a minute ago 177MB ubuntu latest 08d22c0ceb15 7 weeks ago 77.8MB # create a service with 2 repricas root@node01:~# docker service create --name swarm_cluster --replicas=2 -p 80:80 nginx-server:latest mwjf6rf9doc32vhu2j7mapwtd 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 mwjf6rf9doc3 swarm_cluster replicated 2/2 nginx-server:latest *:80->80/tcp # inspect the service root@node01:~# docker service inspect swarm_cluster --pretty ID: mwjf6rf9doc32vhu2j7mapwtd 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 q8womy3plgbp swarm_cluster.1 nginx-server:latest node02.srv.world Running Running about a minute ago mndbkwgq657i 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 repricas, configure like follows. |
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# change repricas 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 q8womy3plgbp swarm_cluster.1 nginx-server:latest node02.srv.world Running Running 2 minutes ago mndbkwgq657i swarm_cluster.2 nginx-server:latest node01.srv.world Running Running 2 minutes ago xkap1rkn7afu swarm_cluster.3 nginx-server:latest node03.srv.world Running Running 12 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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