CODEWITHSUNDEEP
network-programmingdockerkubernetes
smeeb
smeeb

Reputation: 29567

Doesn't Docker port binding obviate the need for Kubernetes' complex networking model?

Kubernetes has a pretty complicated networking model that appears to be predicated upon circumventing a critical flaw with Docker's default networking:

By default Docker containers cannot be contacted directly from the outside world, because their IP addresses are local/private to the subnet they're on.

To circumvent this, Kubernetes has a very complex network model that, amongst other things, requires you to carve out your own flat IP space that is then shared by all hosts and containers (pods), thus giving each pod its own public IP.

But I ask: isn't this already addressed by Docker port binding? If not, then what about port binding is still lacking, that requires Kubernetes to use the networking solution that they use?

Upvotes: 1

Views: 123

Answers (1)

Alex Robinson
Alex Robinson

Reputation: 13397

This is well described in the motivation section of Kubernetes's networking design doc.

Essentially, relying on port binding requires dynamic port mapping to avoid conflicts between different containers wanting the same port (e.g. a lot of applications will want port 80). While dynamic port mapping can be made to work, it also causes a lot of problems, as outlined in the doc.

Upvotes: 1

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