tested with Docker CE on Ubuntu and Slackware
assuming you got docker up and running
Note – you need the Swarm nodes to be able to pull the images from a common repository
on the node to become manager and leader
inititialize the cluster
docker swarm init --help docker swarm init --advertise-addr CLUSTER-IP docker swarm join-token manager docker swarm join-token worker
add more managers
docker swarm join --token MANAGER-TOKEN x.x.x.x:2377
add more workers
docker swarm join --token WORKER-TOKEN x.x.x.x
on some manager node
run an instance cluster-wide
docker service create --help docker service create --name train-shuttle --hostname train-shuttle --workdir /root pbraun9/ubuntu # --replicas 2 # --mode=global
status
docker node ls docker node ps # --no-trunc docker service ls docker service ps train-shuttle docker service logs train-shuttle
stop/REMOVE
docker service rm train-shuttle
there’s no absolute need for docker-compose. we can either define the number of replicas ourselves
docker service create --replicas 2 ...
or enable global mode
docker service create --mode=global ...
promote a worker to a leader/manager
docker node promote HOSTNAME
downgrade a leader/manager to a worker node
docker node demote HOSTNAME
the docker daemon doesn’t listen on additional ports but Swarm does make your farm somehow insecure in case it has external interfaces, therefore MAYBE ENABLE SYSTEM FIREWALL FOR ONCE (load before dockerd)
vi /etc/rc.d/rc.inet1
echo -n nftables...
/usr/sbin/nft -f /etc/nftables.conf && echo done || echo FAIL
re-balance the instances after a host has recovered (--replicas mode)
docker service ls docker service update SERVICE --detach=false --force
for a worker to leave the cluster
docker swarm leave
for a manager to leave the cluster
docker swarm leave --force
prepare a test image PER NODE, and test it with Docker first
docker pull larsks/thttpd docker images/ mkdir /var/tmp/content/
node 1
echo '<p>kube1' > /var/tmp/content/index.html docker run -d --name thttpd-app -p 80:80 -v /var/tmp/content:/content larsks/thttpd /content
node 2
echo '<p>kube2' > /var/tmp/content/index.html docker run -d --name thttpd-app -p 80:80 -v /var/tmp/content:/content larsks/thttpd /content
node 3
echo '<p>kube3' > /var/tmp/content/index.html docker run -d --name thttpd-app -p 80:80 -v /var/tmp/content:/content larsks/thttpd /content
and check
http://NODE1/ http://NODE1/ http://NODE1/
https://docs.docker.com/engine/swarm/swarm-tutorial/#open-protocols-and-ports-between-the-hosts
https://platform9.com/blog/compare-kubernetes-vs-docker-swarm/
http://callistaenterprise.se/blogg/teknik/2017/03/09/go-blog-series-part5/
docker swarm init https://docs.docker.com/engine/reference/commandline/swarm_init/
https://docs.docker.com/engine/reference/builder/#notes-about-specifying-volumes
https://docs.docker.com/engine/tutorials/dockervolumes/#mount-a-host-directory-as-a-data-volume
https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/
https://docs.docker.com/registry/recipes/mirror/
docker swarm leave https://docs.docker.com/engine/reference/commandline/swarm_leave/
What is opposite of docker swarm init? https://stackoverflow.com/questions/48345602/what-is-opposite-of-docker-swarm-init
https://docs.docker.com/engine/reference/commandline/service_create/
https://docs.docker.com/engine/swarm/services/
https://docs.docker.com/engine/swarm/key-concepts/
https://success.docker.com/article/mode-global-can-cause-platform-mismatch-for-replica
https://hub.docker.com/r/larsks/thttpd
Docker Swarm connection errors while VMware Snapshots https://access.redhat.com/discussions/2950631
Docker Swarm: bulk sync to node failed, https://forums.docker.com/t/docker-swarm-bulk-sync-to-node-failed/91510
Swarm is having occasional network connection problems between nodes. #32195 https://github.com/moby/moby/issues/32195