CODEWITHSUNDEEP
dockerrancher
pourmesomecode
pourmesomecode

Reputation: 4318

What's the host in Docker + Rancher context?

So I see host mentioned a few times in the docs. There's also networking_mode=host you can add in the yml file.

So what I assume the host is, is the machine the VM (Docker) is run on?

So if I set networking mode to host, the port mapping etc will be handled on my local machine. Where in the yml i could do 3001:3000 that'll map port 3001 to the container port of 3000. With networking mode host that mapping will be handled on my local machine.

Now, when we're hosting containers on rancher. And we set the networking_mode=host. What's host in that context? Is it the VM or ec2 or whatever that is running my rancher? Or the VM/ec2 that's running my host stack?

I can't grasp it from the docs.

Upvotes: 0

Views: 209

Answers (1)

leodotcloud
leodotcloud

Reputation: 1960

A container runs on a single server, a.k.a host, running Docker.

Host can be either be a bare metal server, Virtual machine running on your laptop or an EC2 instance.

Rancher itself is a container running on a host. Now when you build a cluster, you can add the host that's running the Rancher container or you can choose to keep things isolated and start adding totally different hosts.

If you choose networking_mode=host, the container is using the host networking stack and if you don't the container gets it's own networking stack. When running in host networking mode, the application running inside the container binds directly to the host network interfaces, so there is no port mapping happening.

In case you are interested in more details, I have discussed a lot about networking in the first half of this talk: https://www.youtube.com/watch?v=GXq3FS8M_kw. Let me know if you have more questions.

Upvotes: 2

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