Kubernetes Tools

Rancher25.6k★

Rancher gives you a web dashboard to manage all your Kubernetes clusters from one place. It's a control panel that sits on top of Kubernetes and makes the painful stuff (deploying apps, managing access, monitoring health) less painful. The core platform is fully open source under Apache 2.0. You get multi-cluster management, a built-in app catalog, RBAC (role-based access control, who can do what on which cluster), and monitoring out of the box. SUSE, which owns Rancher, sells enterprise support and additional security features, but the open source version is production-ready. Self-hosting is the default: Rancher runs on a Kubernetes cluster itself. Initial setup takes a few hours if you know Kubernetes. If you don't know Kubernetes, Rancher isn't going to save you from that learning curve. It manages complexity; it doesn't eliminate it. Solo developers: you probably don't need this. Use K3s directly. Small teams running 1-2 clusters: Rancher is great, and the free tier covers everything. Growing teams with 5+ clusters across environments: this is where Rancher really shines. The catch: Rancher managing Kubernetes means running Kubernetes to manage Kubernetes. If you're not already committed to K8s, this adds complexity rather than reducing it.

Cilium24.3k★

It uses eBPF (a technology that lets you run programs inside the Linux kernel) to handle networking, security, and observability without the performance overhead of traditional approaches. The open source version is free under Apache 2.0. It handles all CNI (Container Network Interface) duties plus L3/L4/L7 network policies, transparent encryption, service mesh capabilities, and Hubble for network observability. CNCF graduated project. Isovalent (the company behind Cilium, now part of Cisco) sells Cilium Enterprise with a management console, advanced threat detection, and enterprise support. Pricing isn't public. Expect significant enterprise pricing. Self-hosting is the default. Cilium replaces your Kubernetes CNI plugin. Install via Helm and it takes over networking for the cluster. Setup is moderate if you're familiar with Kubernetes networking. Migration from an existing CNI can be tricky. Solo developers: unless you're learning Kubernetes networking, this is beyond what you need. Small teams: if network policies and observability matter, Cilium is worth the setup. Growing teams: the observability through Hubble alone justifies it. The catch: eBPF requires a recent Linux kernel (5.4+). Older kernels or non-Linux nodes won't work. And swapping your CNI plugin on an existing cluster is not a trivial operation.

Ingress NGINX19.5k★

It's the official NGINX-based ingress controller maintained by the Kubernetes project. You define routing rules in YAML, and it configures NGINX to make them happen. Apache 2.0. Handles TLS termination, rate limiting, basic auth, WebSocket proxying, and canary deployments. Pairs with cert-manager for automatic Let's Encrypt certificates. Fully free. No paid tier. This is community infrastructure maintained by the Kubernetes SIG. The catch: NGINX config through Kubernetes annotations is clunky. Complex routing rules turn into annotation soup that's hard to debug. Performance is solid for most workloads, but if you need advanced traffic management (circuit breaking, retries with budgets, traffic mirroring), you'll outgrow it. And there's a confusing namespace issue: this is kubernetes/ingress-nginx (community), not nginxinc/kubernetes-ingress (NGINX Inc's commercial version). Make sure you install the right one.

cert-manager13.8k★

Cert-manager automatically provisions and renews TLS certificates. You tell it what domains you need certificates for, it talks to Let's Encrypt (or your internal CA), and your certs just work. No more manually renewing SSL certificates or writing cron jobs to handle expiration. Fully free under Apache 2.0. It's a CNCF project, which means it has serious institutional backing and isn't going anywhere. Works with Let's Encrypt, Vault, Venafi, and most certificate authorities. Installation is a single Helm chart. The catch: this is Kubernetes-only. If you're running Docker Compose or bare metal, look at Caddy (automatic HTTPS built in) or certbot. And while cert-manager itself is simple, debugging certificate issuance failures requires understanding DNS challenges, ACME protocols, and Kubernetes RBAC. When it works, it's invisible. When it doesn't, you're reading three layers of logs.

Flux8.1k★

Push a commit, cluster updates itself. Flux is a GitOps tool that makes Git the source of truth for your infrastructure. It watches your Git repos and container registries, detects changes, and reconciles your cluster to match. No CI/CD pipeline needed for deployments. Git IS the pipeline. Fully free under Apache 2.0. CNCF graduated project. You get Git repository syncing, Kustomize and Helm support, image update automation, multi-tenancy, and notifications (Slack, Teams, webhooks). It runs as a set of controllers inside your Kubernetes cluster. The catch: Flux is Kubernetes-only. If you're not on Kubernetes, this isn't for you. The learning curve assumes you already understand Kubernetes concepts (CRDs, controllers, namespaces, RBAC). Debugging reconciliation failures requires understanding both Flux's logic AND Kubernetes internals. And compared to Argo CD (the other major GitOps tool), Flux has no built-in UI; you either use the CLI or third-party dashboards like Weave GitOps.

Knative6.0k★

Kestra orchestrates data pipelines and workflows using declarative YAML, with a visual editor, 500+ plugins, and built-in scheduling. Knative Serving adds that capability to your existing cluster. Instead of paying for idle pods, your services sleep and wake up on demand. Like AWS Lambda but on your own infrastructure. Apache 2.0. CNCF incubating project. Knative handles request-based autoscaling (including scale-to-zero), traffic splitting for canary deployments, automatic TLS, and revision management. You deploy a service, and Knative manages the lifecycle. Fully free. No paid tier from the project. Google Cloud Run is built on Knative if you want managed. The catch: Knative adds significant complexity to your cluster. It requires a networking layer (Istio, Kourier, or Contour), and the cold start latency when scaling from zero can be seconds, not milliseconds. If your services need instant response times, scale-to-zero defeats the purpose. And the resource overhead of Knative's own components (controller, activator, autoscaler, networking) means it only makes sense if you're running enough services that the savings from scale-to-zero outweigh the platform cost.

kargo3.3k★

Kargo orchestrates that promotion pipeline. Consider it a GitOps-native way to move application versions through stages with approval gates and verification steps. Apache 2.0, Go. Built by the creators of Argo CD. Kargo doesn't replace your CI. It sits on top of your GitOps tools (Argo CD, Flux) and manages the lifecycle of getting a change from one environment to the next. It watches for new container images or Helm chart versions and can auto-promote or require manual approval. Fully free and open source. No paid tier currently. Akuity (the company behind it) offers a managed Argo CD platform but Kargo itself is free to self-host. Self-hosting requires a Kubernetes cluster (it runs as a controller). Setup is straightforward if you already have Argo CD running. Ops burden is moderate. It's another controller to monitor. Solo: overkill unless you're learning GitOps. Small teams with multiple environments: this is where Kargo starts making sense. Medium to large: strong fit for managing promotion across many services. The catch: it's young. The API is still evolving, documentation is thin in places, and you're locked into the GitOps model. If you're not already using Argo CD or Flux, adopting Kargo means adopting GitOps first.