Docker : Configure Swarm Cluster2018/06/12 |
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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] | Configure Swarm Cluster on Manager Node. |
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root@node01:~# docker swarm init
Swarm initialized: current node (kstx00g477nbhtalspbkv4wfl) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-3dt7tg314vzxg8bb5ax64ldq6cqxznqj1rhozof1ewp5qmq3al-066oh7rcdnbt0mx1ysxnw3k3d 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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| [3] | 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-1-3dt7tg314vzxg8bb5ax64ldq6cqxznqj1rhozof1ewp5qmq3al-066oh7rcdnbt0mx1ysxnw3k3d 10.0.0.51:2377 This node joined a swarm as a worker. |
| [4] | 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 kstx00g477nbhtalspbkv4wfl * node01.srv.world Ready Active Leader pzbva8u3pj1d4fscynfjle4bd node02.srv.world Ready Active z380j4bwyp9d2dy00dtzh56bv node03.srv.world Ready Active |
| [5] | After creating Swarm Cluster, next, configure services that the Swarm Cluster provides. Create the same container image on all Nodes for the service first. On this exmaple, create a Container image which provides http service like follows on all Nodes. |
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root@node01:~#
vi Dockerfile FROM ubuntu MAINTAINER ServerWorld <admin@srv.world> RUN apt-get update RUN apt-get -y install apache2 RUN echo "node01" > /var/www/html/index.html EXPOSE 80 CMD ["/usr/sbin/apachectl", "-D", "FOREGROUND"] docker build -t apache2_server:latest ./ |
| [6] | 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. By the way, 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 apache2_server latest 6a1cbac1a456 13 minutes ago 218MB ubuntu latest 113a43faa138 6 days ago 81.2MB # create a service with 2 repricas root@node01:~# docker service create --name swarm_cluster --replicas=2 -p 80:80 apache2_server:latest jo17duq5qiupchrw9bcdrqi89 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 jo17duq5qiup swarm_cluster replicated 2/2 apache2_server:latest *:80->80/tcp # inspect the service root@node01:~# docker service inspect swarm_cluster --pretty ID: jo17duq5qiupchrw9bcdrqi89 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: apache2_server:latest 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 ... d2am5warj1w2 swarm_cluster.1 apache2_server:latest node02.srv.world Running Running about a minute ago k6ql1oxoeemh swarm_cluster.2 apache2_server:latest node01.srv.world Running Running about a minute ago # verify it works normally root@node01:~# curl http://node01.srv.world node02 root@node01:~# curl http://node01.srv.world node01 root@node01:~# curl http://node01.srv.world node02 root@node01:~# curl http://node01.srv.world node01 |
| [7] | 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 ... d2am5warj1w2 swarm_cluster.1 apache2_server:latest node02.srv.world Running Running 4 minutes ago k6ql1oxoeemh swarm_cluster.2 apache2_server:latest node01.srv.world Running Running 4 minutes ago eitu3hkbd5h4 swarm_cluster.3 apache2_server:latest node03.srv.world Running Running about a minute ago # verify working root@node01:~# curl http://node01.srv.world node02 root@node01:~# curl http://node01.srv.world node03 root@node01:~# curl http://node01.srv.world node01 |
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