add nodes to dockers swarm from different servers

Question

I am new to docker swarm, I read documentation and googled to the topic, but results was vague, Is it possible to add worker or manager node from distinct and separate Virtual private servers?

Answer 1

Idea is to connect many non-related hosts into a swarm which then creates distribution over many systems and resiliency in case of any HW failures. The only thing you need to watch out for is that the internet connection between the hosts is stable and that all of the needed ports based of the official documentation are open. And you are good to go :)

Oh and between managers you want a VERY stable internet connection without any random ping spikes, or you may encounter weird behaviour (because of consensus with raft and decision making).

other than that it is good

Answer 2

Refer to Administer and maintain a swarm of Docker Engines

In production the best practice to maximise swarm HA is to spread your swarm managers across multiple availability zones. Availability Zones are geo-graphically co-located but distinct sites. i.e. instead of having a single London data centre, have 3 - each connected to a different internet and power utility. That way, if any single ISP or Power utility has an outage, you still have 2 data centres connected to the internet.

Swarm was designed with this kind of Highly available topology in mind and can scale to having its managers - and workers - distributed across nodes in different data centres.

However, Swarm is sensitive to latency over longer distances - so global distribution is not a good idea. In a single city, Data center to Data centre latencies will be in the low 10s of ms. Which is fine.

Connecting data centres in different cities / continents moves the latency to the low, to mid 100s of ms which does cause problems and leads to instability.

Otherwise, go ahead. Build your swarm across AZ distributed nodes.