Before you run k8s: the bare metal cluster readiness checklist

So you've decided to ditch the public cloud hype and go bare metal with Kubernetes? Smart move. While your friends are burning cash on cloud bills that would make a CFO cry, you're about to build something that actually makes sense from both a performance and cost perspective.

But hold up: before you start spinning up that cluster, let's make sure you're setting yourself up for success, or in more practical terms, avoiding a world of pain that comes from misconfiguring clusters.

Bare metal K8s isn't just "install and pray." It's more like "measure twice, cut once," except the measuring part involves seven critical checkpoints that'll save you from a lot of 3 AM emergency calls.

1. Hardware Requirements and Specifications

When it comes to bare metal, your hardware is your cloud provider. No more magical auto-scaling instances or "just throw money at it" solutions. You need to actually think about what you're building.

Start with the boring basics: in principle, master nodes require at least 2 CPU cores and 2GB RAM, and worker nodes can get away with a single core and 1GB, but that's like putting a motorcycle engine in a small truck, and will only work for testing.

For real-world production workloads, you'll want to start with 4+ CPU cores and 8+ GB RAM for master nodes, and at least 2 CPU cores with 4+ GB RAM for workers. Anything less and you'll be explaining performance issues to impatient developers.

The real game-changer here is storage. Forget those spinning rust drives your datacenter team keeps pushing. NVMe SSDs aren't just "nice to have" anymore; they completely change the game when it comes to Kubernetes. Your application teams will thank you, and your monitoring dashboards will look a lot less scary.

Don't forget that etcd is incredibly picky about storage latency. Anything over 10ms will make your cluster feel sluggish, so those NVMe drives aren't optional for master nodes either, they're mandatory for sanity.

Pro tip: Keep your hardware homogeneous. Mixed configurations are like that one friend who always complicates dinner plans.

2. Network Architecture and Connectivity

Network planning for bare metal K8s is where many teams face-plant. You should prepare for at least 1 Gbps bandwidth between nodes, though 10 Gbps is better if you're running data-intensive workloads that don't like waiting around.

Map out your IP ranges like you're planning a city. Pod networks, service networks, and node networks each need their own neighborhoods, and trust us, you don't want them fighting over addresses later. Make your cluster CIDR big enough that you won't outgrow it in six months when your "small pilot project" suddenly becomes business-critical.

Network redundancy isn't paranoia, it's insurance. Single points of failure in networking are like single points of failure in parachutes. Theoretically acceptable until you really need them to work. Bond those interfaces, plan redundant paths, and sleep better at night.

Also, plan your firewall rules ahead of time: you'll need ports 6443 for the API server, 2379-2380 for etcd, 10250 for kubelet, and whatever your CNI plugin requires. Trust us, discovering missing ports during deployment is not something you want to deal with.

And please, figure out your ingress strategy now. Whether you're going with MetalLB, HAProxy, or a custom load balancer setup, make your decision now to avoid explaining to stakeholders that the demo isn't working because traffic can't reach the cluster.

While you're at it, pick your Container Network Interface (CNI) plugin—Calico for policy-heavy environments, Flannel for simplicity, or Cilium if you want the latest and greatest in eBPF-powered networking.

3. Operating System Configuration, K8s version, and Security

Pick your OS like you're picking a long-term relationship. It needs to be stable, well-supported, and not likely to surprise you with weird quirks at inconvenient times. Ubuntu LTS, RHEL, or one of those container-optimized distros are all safe bets. 

Whatever you choose, keep it consistent across nodes unless you enjoy debugging problems that only happen on "that one weird server."

As for the Kubernetes version, pick it like you're choosing a mortgage rate: go with something stable that you can live with for a while. LTS releases or N-1 versions are usually safer bets than the shiny new release that just dropped, especially when you're the one who'll be troubleshooting any weird edge cases.

Also, stick with kernel versions that are actually supported by your chosen Kubernetes version; running bleeding-edge kernels might sound exciting, but debugging kernel compatibility issues at 2 AM isn't as fun as it sounds.

While you're at it, set up NTP or chrony on all nodes; Kubernetes certificates and distributed systems in general get cranky when clocks drift, and certificate validation failures are a special kind of debugging nightmare that'll make you question your career choices.

Security hardening isn't optional either, even if you're behind seven firewalls and a moat filled with laser sharks. SSH keys, regular updates, and proper firewalls are all must-haves for your setup.

4. Container Runtime Installation and Configuration

Docker might have started this whole container party, but it's time to move on. Containerd or CRI-O are your new best friends. They're lighter, faster, and won't leave you hanging when Kubernetes drops support for something.

Configure resource limits like you're setting boundaries with a toddler. Containers without limits are containers that will happily consume every resource available and then ask for seconds. So set up proper cgroups, configure logging rotation, and implement security policies that make sense for your workloads.

Don't forget to reserve resources for system pods and the kubelet itself. Your nodes need breathing room, or they'll start evicting your applications when things get busy, and explaining to developers why their app got kicked out is never a fun conversation.

And as always, test everything before you commit. Can it pull from your registry? Does it handle resource pressure gracefully? Does it integrate with your monitoring stack? In the future, you will appreciate not feeling disappointed for skipping the boring stuff.

5. Storage Strategy and Persistent Volume Planning

Welcome to the fun part: you get to be your own storage admin now! You're making real decisions about real hardware with real trade-offs.

While local storage is as fast as lightning, it has the durability of a house of cards. Network storage, although more reliable, might bottleneck your applications. So choose your battles based on what your applications really need, not what sounds coolest on paper.

For reference, local storage makes sense for stateless applications, caching layers, or anything that can handle node failures gracefully; network storage is your friend for databases, file shares, or anything that would cause actual panic if a node died unexpectedly.

Static vs dynamic provisioning is another "pick your poison" decision. Static gives you total control, but requires manual work for every volume. Dynamic provisioning is convenient but requires additional infrastructure components. 

Backup strategy is another must-have here. Plan it now, implement it early, and test your restores regularly. The best backup system is worthless if you can't restore from it if everything goes sideways.

6. High Availability Setup & Load Balancing 

If you're building a production cluster with a single master node, we need to have a conversation about risk tolerance. There's a reason why multiple masters with external load balancing became THE industry's best practice: they are the difference between planned maintenance and unplanned outages.

Make sure you run your production environments with multiple master nodes and don't forget that etcd needs an odd number of nodes (3, 5, or 7) for proper quorum. Even numbers are like having a tie-breaking vote that never shows up when you need it most.

Load balancer choice depends on your environment and budget. HAProxy and nginx are solid software options that won't cost you extra licensing fees, and hardware load balancers work great if you've got the budget and existing infrastructure. Either way, health checks are mandatory.

For application traffic, MetalLB has become the go-to solution for bare metal load balancing services. It's like having a public cloud provider's load balancer functionality without the skyrocketing bills.

Pair it with a good ingress controller, and you've got a traffic management setup that rivals anything the hyperscalers offer. Some solid options we recommend are: nginx-ingress for battle-tested reliability, Traefik for automatic service discovery magic, or Istio if you want to dive deep into service mesh complexity.

7. Monitoring, Logging, and Backup Infrastructure

Prometheus and Grafana have become the de facto standard in this case for good reason. They're open source, they scale well, and they won't surprise you with licensing costs when your cluster grows.

Set up alerting that will actually help you, rather than just create continuous noise. Node failures, resource exhaustion, and application downtime definitely deserve alerts. Every container restart or minor hiccup? Probably not.

Centralized logging saves sanity. When something breaks (and something will break), you don't want to SSH into dozens of nodes playing detective.

etcd backups are like insurance, boring until you desperately need them. Automate them to run every few hours, store them somewhere that won't disappear if your cluster has a bad day, test the restore process regularly (preferably not when everything is already on fire), and document the procedures so your future self will thank you instead of cursing your past decisions.

Start Building with Latitude.sh 

Once you complete every part of this checklist, you're about to join the ranks of organizations running Kubernetes the way it was meant to be run: on real hardware, with real performance, and without the public cloud tax. 

It's more work upfront, but the payoff in performance, cost savings, and control is really worth it.

Document everything as you build. Create runbooks for everyday tasks and train your team on bare metal operations. The extra operational overhead is real, but it's manageable with the proper preparation and tooling.

And if you want to start building it right now, sign up to Latitude.sh! Get the most out of your K8s cluster on top of the leading bare metal platform available today.