# Setting up Kubernetes - Kubernetes is made of many components that require careful configuration - Secure operation typically requires TLS certificates and a local CA (certificate authority) - Setting up everything manually is possible, but rarely done (except for learning purposes) - Let's do a quick overview of available options! --- ## Local development - Are you writing code that will eventually run on Kubernetes? - Then it's a good idea to have a development cluster! - Instead of shipping containers images, we can test them on Kubernetes - Extremely useful when authoring or testing Kubernetes-specific objects (ConfigMaps, Secrets, StatefulSets, Jobs, RBAC, etc.) - Extremely convenient to quickly test/check what a particular thing looks like (e.g. what are the fields a Deployment spec?) --- ## One-node clusters - It's perfectly fine to work with a cluster that has only one node - It simplifies a lot of things: - pod networking doesn't even need CNI plugins, overlay networks, etc. - these clusters can be fully contained (no pun intended) in an easy-to-ship VM or container image - some of the security aspects may be simplified (different threat model) - images can be built directly on the node (we don't need to ship them with a registry) - Examples: Docker Desktop, k3d, KinD, MicroK8s, Minikube (some of these also support clusters with multiple nodes) --- ## Managed clusters ("Turnkey Solutions") - Many cloud providers and hosting providers offer "managed Kubernetes" - The deployment and maintenance of the *control plane* is entirely managed by the provider (ideally, clusters can be spun up automatically through an API, CLI, or web interface) - Given the complexity of Kubernetes, this approach is *strongly recommended* (at least for your first production clusters) - After working for a while with Kubernetes, you will be better equipped to decide: - whether to operate it yourself or use a managed offering - which offering or which distribution works best for you and your needs --- ## Node management - Most "Turnkey Solutions" offer fully managed control planes (including control plane upgrades, sometimes done automatically) - However, with most providers, we still need to take care of *nodes* (provisioning, upgrading, scaling the nodes) - Example with Amazon EKS ["managed node groups"](https://docs.aws.amazon.com/eks/latest/userguide/managed-node-groups.html): *...when bugs or issues are reported [...] you're responsible for deploying these patched AMI versions to your managed node groups.* --- ## Managed clusters differences - Most providers let you pick which Kubernetes version you want - some providers offer up-to-date versions - others lag significantly (sometimes by 2 or 3 minor versions) - Some providers offer multiple networking or storage options - Others will only support one, tied to their infrastructure (changing that is in theory possible, but might be complex or unsupported) - Some providers let you configure or customize the control plane (generally through Kubernetes "feature gates") --- ## Choosing a provider - Pricing models differ from one provider to another - nodes are generally charged at their usual price - control plane may be free or incur a small nominal fee - Beyond pricing, there are *huge* differences in features between providers - The "major" providers are not always the best ones! - See [this page](https://kubernetes.io/docs/setup/production-environment/turnkey-solutions/) for a list of available providers --- ## Kubernetes distributions and installers - If you want to run Kubernetes yourselves, there are many options (free, commercial, proprietary, open source ...) - Some of them are installers, while some are complete platforms - Some of them leverage other well-known deployment tools (like Puppet, Terraform ...) - There are too many options to list them all (check [this page](https://kubernetes.io/partners/#conformance) for an overview!) --- ## kubeadm - kubeadm is a tool part of Kubernetes to facilitate cluster setup - Many other installers and distributions use it (but not all of them) - It can also be used by itself - Excellent starting point to install Kubernetes on your own machines (virtual, physical, it doesn't matter) - It even supports highly available control planes, or "multi-master" (this is more complex, though, because it introduces the need for an API load balancer) --- ## Manual setup - The resources below are mainly for educational purposes! - [Kubernetes The Hard Way](https://github.com/kelseyhightower/kubernetes-the-hard-way) by Kelsey Hightower - step by step guide to install Kubernetes on Google Cloud - covers certificates, high availability ... - *“Kubernetes The Hard Way is optimized for learning, which means taking the long route to ensure you understand each task required to bootstrap a Kubernetes cluster.”* - [Deep Dive into Kubernetes Internals for Builders and Operators](https://www.youtube.com/watch?v=3KtEAa7_duA) - conference presentation showing step-by-step control plane setup - emphasis on simplicity, not on security and availability --- ## About our training clusters - How did we set up these Kubernetes clusters that we're using? -- - We used `kubeadm` on freshly installed VM instances running Ubuntu LTS 1. Install Docker 2. Install Kubernetes packages 3. Run `kubeadm init` on the first node (it deploys the control plane on that node) 4. Set up Weave (the overlay network) with a single `kubectl apply` command 5. Run `kubeadm join` on the other nodes (with the token produced by `kubeadm init`) 6. Copy the configuration file generated by `kubeadm init` - Check the [prepare VMs README](https://@@GITREPO@@/blob/master/prepare-vms/README.md) for more details --- ## `kubeadm` "drawbacks" - Doesn't set up Docker or any other container engine (this is by design, to give us choice) - Doesn't set up the overlay network (this is also by design, for the same reasons) - HA control plane requires [some extra steps](https://kubernetes.io/docs/setup/independent/high-availability/) - Note that HA control plane also requires setting up a specific API load balancer (which is beyond the scope of kubeadm) ??? :EN:- Various ways to install Kubernetes :FR:- Survol des techniques d'installation de Kubernetes