Docker : Swarm Cluster2024/06/13 |
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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.
-----------+---------------------------+--------------------------+------------
| | |
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 (qpitbhvhbl3ztnwbhuuon492r) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-5lrebm28fiqi22ihg0ueehtjumql9d3skaj3uqevdj56qwy2wg-dv59ktfk632756mi4idp6v2tp 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-1-5lrebm28fiqi22ihg0ueehtjumql9d3skaj3uqevdj56qwy2wg-dv59ktfk632756mi4idp6v2tp 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 qpitbhvhbl3ztnwbhuuon492r * node01.srv.world Ready Active Leader 24.0.7 je4dfokbmb5roj26yvb6ynhcw node02.srv.world Ready Active 24.0.7 bz7gjckb75rzaz5gm4mwaiyir node03.srv.world Ready Active 24.0.7 |
| [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 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 c9fc449433be 59 seconds ago 123MB dlp.srv.world:5000/ubuntu my-registry 17c0145030df 13 days ago 76.2MB # create a service with 2 replicas root@node01:~# docker service create --name swarm_cluster --replicas=2 -p 80:80 nginx-server:latest versions of the image. v4z6papfefidlhkpp5mampz3t 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 v4z6papfefid swarm_cluster replicated 2/2 nginx-server:latest *:80->80/tcp # inspect the service root@node01:~# docker service inspect swarm_cluster --pretty ID: v4z6papfefidlhkpp5mampz3t 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 41l5x91uu7w0 swarm_cluster.1 nginx-server:latest node03.srv.world Running Running about a minute ago mvpi4lftdcg5 swarm_cluster.2 nginx-server:latest node02.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 node03 root@node01:~# curl node01.srv.world Nginx on node02 root@node01:~# curl node01.srv.world Nginx on node03 |
| [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 convergedroot@node01:~# docker service ps swarm_cluster ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS 41l5x91uu7w0 swarm_cluster.1 nginx-server:latest node03.srv.world Running Running 4 minutes ago mvpi4lftdcg5 swarm_cluster.2 nginx-server:latest node02.srv.world Running Running 4 minutes ago zirr3725j2y7 swarm_cluster.3 nginx-server:latest node01.srv.world Running Running 39 seconds ago # verify accesses 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 node03 |
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