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escardin | 5 years ago
Following the kubeadm getting started guide on the kubernetes.io site can get you an 'ha', 'production ready' going in a couple hours. Most of it is pretty mechanical, and only needs a couple key decisions, mainly your networking plugin. Generally the most popular ones have instructions as part of the getting started guide, making the process straight forward.
Where it quickly becomes difficult is after this step. You have a cluster ready to serve workloads, but it has no storage, no ingress/external load balancer.
Storage can be as simple as NFS volumes (you don't even need a provider for this, but you should use one anyway). Rook/Ceph will work, but now you've just taken on two complex technologies instead of one.
Without an external load balancer of some sort, you will have trouble getting traffic into your cluster, and it likely won't be actually HA. You can use MetalLB for this, or appliances. If you're just starting out though, you can totally get away with setting up CNAME aliases in DNS to your nodes in a round robin type fashion. It won't be HA, but it will work, and is simple and straight forward.
Ingress is pretty easy to setup for the most part. Usually just applying an available manifest with a tweak or two. If you go the CNAME route, you will need an ingress setup so you can serve http/https on standard ports without too many issues.
If you do all these things, then you have a real deal cluster. Things like ingresses are recommended even if you're running in the cloud, so you may find that you're not all that far off from what you might find there.
Overall, the biggest trouble is all the choices you need to make. If you're starting out, maybe read up on two or three of the most popular choices for each step, and then just pick one. Anything that exists entirely within the cluster can usually be expressed purely as source controlled manifests, and kubeadm deployments can be simple shell scripts if you don't make them do everything (i.e. only support one container driver, not all of them).
One major caveat; If you screw up your network layer, you basically have to start over. This isn't strictly true, but it's the one where you are often better off starting over when you need to make fundamental changes to your network setup (like podCIDR and serviceCIDR or your network plugin). Pretty much everything else can be made to work with multiple setups at once, or you just need to delete and redeploy that component.
shaklee3|5 years ago