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by moondev 3624 days ago
Is flannel used in Kubernetes for networking by default? Or is it something that needs to enabled and configured separately?
2 comments
amouat 3624 days ago
Kubernetes has a requirement that containers (more accurately "pods") can connect via a "flat networking space". How this is achieved varies between deployments, flannel, calico and weave are all common approaches. Kelsey Hightower's "Kubernetes the Hard Way" simply configured it at the router level: https://github.com/kelseyhightower/kubernetes-the-hard-way/b...
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moondev 3624 days ago
That makes sense. Thanks for the link as well, i've been looking for something exactly like it. Looks like a great resource!
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lobster_johnson 3624 days ago
Kubernetes doesn't have a "default" as such. It requires something external to manage the subnet, and needs to be configured to use it.

However, if you run it on AWS, it can automatically configure a bridge (cbr0) and configure up the VPC routing table for you.

GCE (Google's managed Kubernetes on Google Cloud) also handles this automatically.

There's also experimental support for Flannel built into K8s, which can be enabled with a flag. Not sure if it's worth using.

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bboreham 3624 days ago
Nitpick: Google's managed Kubernetes is called GKE.

However the OSS Kubernetes has code to configure routes on GCE same as it does for AWS.

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