Play with docker 1.12

saundy

　　This command declares a desired state on your swarm of 2 nginx containers, reachable as a single, internally load balanced service on port 80 of any node in your swarm.  Internally, we make this work using Linux IPVS, an in-kernel Layer 4 multi-protocol load balancer that’s been in the Linux kernel for more than 15 years.  With IPVS routing packets inside the kernel, swarm’s routing mesh delivers high performance container-aware load-balancing.
　　When you create services, can optionally create replicated or global services.  Replicated services mean any number of containers that you define will be spread across the available hosts.  Global services, by contrast, schedule one instance the same container on every host in the swarm.
　　Let’s turn to how Docker provides resiliency.  Swarm mode enabled engines are self-healing, meaning that they are aware of the application you defined and will continuously check and reconcile the environment when things go awry.  For example, if you unplug one of the machines running an nginx instance, a new container will come up on another node.  Unplug the network switch for half the machines in your swarm, and the other half will take over, redistributing the containers amongst themselves.  For updates, you now have flexibility in how you re-deploy services once you make a change. You can set a rolling or parallel update of the containers on your swarm.