Docker Swarm – LinTechOps.com

Run the following command to initialize docker swarm.

root@ip-172-31-91-97:/home/ubuntu# docker swarm init --advertise-addr 52.203.29.219
 Swarm initialized: current node (zhqxor0uw79okh8thcm6boj0o) is now a manager.
 To add a worker to this swarm, run the following command:
 docker swarm join --token SWMTKN-1-105nukjje4l0yys14czxrpma8a2cxy1xx2y2n09u490pw1ve4i-4faqsr4p0hrjofywizcp04c6r 52.203.29.219:2377
 To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

To join your node to the master apply the following command in the node server.

root@ip-172-31-93-154:/home/ubuntu# docker swarm join --token SWMTKN-1-105nukjje4l0yys14czxrpma8a2cxy1xx2y2n09u490pw1ve4i-4faqsr4p0hrjofywizcp04c6r 52.203.29.219:2377
 This node joined a swarm as a worker.

To list the nodes:

root@ip-172-31-91-97:/home/ubuntu# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
zhqxor0uw79okh8thcm6boj0o * ip-172-31-91-97 Ready Active Leader 18.09.7
6wc42orryexx8nft23wiz7ekv ip-172-31-93-154 Ready Active 18.09.7

Trying to launch 5 replicas of the nginx container using the following command.

root@ip-172-31-91-97:/home/ubuntu# docker service create --replicas 5 -p 80:80 --name web nginx
 mqjtaf0ir040bt6ueyrlm782d
 overall progress: 5 out of 5 tasks 
 1/5: running   [==================================================>] 
 2/5: running   [==================================================>] 
 3/5: running   [==================================================>] 
 4/5: running   [==================================================>] 
 5/5: running   [==================================================>] 
 verify: Service converged

Find out the status of the service, by using the following command:

root@ip-172-31-91-97:/home/ubuntu# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
mqjtaf0ir040 web replicated 5/5 nginx:latest *:80->80/tcp

Please access the master IP “52.203.29.219” in the web browser to see the Nginx page

How it’s orchestrated to the different nodes by using the following command:

Run the “docker ps” in both Master and Node to see the clusters.

In Master:

root@ip-172-31-91-97:/home/ubuntu# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
c8ba8995c33f nginx:latest "nginx -g 'daemon of…" 17 minutes ago Up 17 minutes 80/tcp web.1.kmsc094t6yb7ghfcnt0758gc5
561248a69f72 nginx:latest "nginx -g 'daemon of…" 17 minutes ago Up 17 minutes 80/tcp web.4.dvhd6iiw9pu9w7guhwabgqz1i

In Node:

root@ip-172-31-93-154:/home/ubuntu# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1238146e70b5 nginx:latest "nginx -g 'daemon of…" 17 minutes ago Up 17 minutes 80/tcp web.2.im1a7ktqlatxx0jum4h8ce0gv
e170b9d89acd nginx:latest "nginx -g 'daemon of…" 17 minutes ago Up 17 minutes 80/tcp web.5.ippgbdeevik8s7cja241lebes
aabfb9c3fa7b nginx:latest "nginx -g 'daemon of…" 17 minutes ago Up 17 minutes 80/tcp web.3.on6grrbbsyhodx401oy31p9d9

Scale up container using the following command:

root@ip-172-31-91-97:/home/ubuntu# docker service scale web=8
 web scaled to 8
 overall progress: 8 out of 8 tasks 
 1/8: running   [==================================================>] 
 2/8: running   [==================================================>] 
 3/8: running   [==================================================>] 
 4/8: running   [==================================================>] 
 5/8: running   [==================================================>] 
 6/8: running   [==================================================>] 
 7/8: running   [==================================================>] 
 8/8: running   [==================================================>] 
 verify: Waiting 4 seconds to verify that tasks are stable… 
 verify: Service converged

Manager will stop tasks running on that node and launch the replicas on other nodes . In case the other node is a Master because we only have two nodes ( one master and one slave) 🙂

root@ip-172-31-91-97:/home/ubuntu# docker node update --availability drain node
 node

Now our master rescheduled the containers to other node(master)

root@ip-172-31-91-97:/home/ubuntu# docker service ps web
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
kmsc094t6yb7 web.1 nginx:latest master Running Running about an hour ago
mb1h3dk584l2 web.2 nginx:latest master Running Running 3 minutes ago
im1a7ktqlatx _ web.2 nginx:latest node Shutdown Shutdown 4 minutes ago
9hyvj3p54oih web.3 nginx:latest master Running Running 3 minutes ago
on6grrbbsyho _ web.3 nginx:latest node Shutdown Shutdown 4 minutes ago
dvhd6iiw9pu9 web.4 nginx:latest master Running Running about an hour ago
j8mmgjjxy9un web.5 nginx:latest master Running Running 3 minutes ago
ippgbdeevik8 _ web.5 nginx:latest node Shutdown Shutdown 4 minutes ago
s3lmyklnt5t2 web.6 nginx:latest master Running Running 9 minutes ago
9k6moe4r88hr web.7 nginx:latest master Running Running 9 minutes ago
n8xmrybrgzfa web.8 nginx:latest master Running Running 4 minutes ago
7xl49qa3qosj _ web.8 nginx:latest node Shutdown Shutdown 4 minutes ago

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