Docker Swarn is an enterprise-grade secure cluster of docker hosts and an engine for orchestrating microservices apps.
- out of the box you get an encrypted distributed cluster store, encrypted networks, mutual TLS, secure cluster join tokens and a PKI the makes managing and rotating certificate a breeze.
- on the orchestration front, swarm exposes a rich API that allows you to deploy and manage complicated microservices app with ease.
manager - control plane of the cluster, manage the state of the cluster and dispatching tasks to workers
workers - execute work tasks from managers.
the configuration and state are held in distributed etcd database on all managers. It is in memory and extremely up-to-date.
TLS to encrypt communications, authenticate nodes and authorize roles, Auto key rotations
service is the atomic unit of scheduling on a swarm
Build Swarm cluster
- 2377/tcp - secure client to daemon communication
- 7946/tcp and 7946/udp - control plane gossip
- 4789/udp VXLAN based overlay network
lead-follower; followers proxy the request to the leader.
- The odd number of managers
- Don't have too many managers(3-5)
old manager rejoin can pose security concern since it will decrypt all configurations and logs.
docker swarm init --autolock docker swarm update --autolock=true docker swarm unlock docker swarm unlock-key --rotate
this can ask to unlock key before the manager joins the cluster.
docker service create --replicas 1 --name '' docker service ls docker service scale servicename=# docker service update --replicas=# servicename
- replicated (default) - distribute them evenly
2 global (--mode global) - a single replica on every node.-- can't scale
docker service create --name name --publish published=8080,target=80 (routing mesh) docker service create --name name --publish published=8080,target=80,mode=host (Node) docker service create --name name --publish published=8080,target=80,mode=host --mode global (every node)