This article is based on reporting originally published by blocksandfiles.com and a since-deleted blog post by Nutanix senior systems engineer Alexander Ervik Johnsen. Some details could not be independently verified at time of writing.
What Is Nutanix Karbon?
Nutanix Karbon is a curated Kubernetes distribution and management platform built on top of upstream Kubernetes. It abstracts away much of the operational complexity involved in deploying and managing Kubernetes clusters on Nutanix HCI infrastructure, making it easier for enterprise teams to run cloud-native, containerised workloads without deep Kubernetes expertise.
The Air-Gap Problem With Kubernetes
A core operational challenge with standard Kubernetes deployments is external network dependency. During cluster bootstrapping and normal operation, Kubernetes pulls container images and configuration data from public registries such as Docker Hub or gcr.io. This makes running Kubernetes in a fully network-isolated — or air-gapped — environment effectively impossible without additional tooling.
Air-gapped environments are common in:
- Government and defence networks handling classified data
- Industrial control and SCADA systems
- Financial institutions with strict regulatory segmentation requirements
- Organisations defending against ransomware and malware by physically or logically isolating workloads from internet-connected networks
Prior to Karbon 2.0, none of these environments could realistically run Karbon-managed Kubernetes clusters without some form of internet connectivity.
Karbon 2.0: Air-Gap Support Explained
Karbon 2.0 introduces the Karbon Air Gap feature, which allows Kubernetes clusters to operate in network-isolated environments by replacing the dependency on external registries with a locally hosted Docker registry.
According to Ervik Johnsen’s blog post (since removed), the architecture works as follows:
“The Air Gap uses a local Docker registry, hosted on a separate VM, to provide Karbon services. Deploying the Air Gap requires Internet access to download the deployment package from the Nutanix Support Portal and transfer it to a local web server.”
Alexander Ervik Johnsen, Nutanix Senior Systems Engineer
Deployment Workflow
The air-gap deployment process follows a standard sneakernet pattern used in secure environments:
- Download the Karbon Air Gap deployment bundle from the Nutanix Support Portal. This requires a machine with internet access.
- Transfer the bundle to a portable storage device (USB drive, external disk, or similar removable media).
- Transport the storage device physically to the air-gapped site. This step can be performed by Nutanix, a certified system integrator, or the customer’s own staff.
- Install the binaries onto a local web server within the isolated environment.
- Serve container images from the locally hosted Docker registry VM, replacing all external registry calls.
Once the local registry is operational, Kubernetes clusters managed by Karbon pull all required images from within the isolated network, eliminating the external internet dependency entirely.
One-Click Kubernetes Version Upgrades
A historically painful operational task for Kubernetes administrators is performing in-place version upgrades. Without purpose-built tooling, upgrading Kubernetes often means redeploying entire clusters or individual applications — a disruptive, time-consuming process that many teams avoid, leading to clusters running outdated Kubernetes versions.
Karbon 2.0 addresses this directly by introducing one-click Kubernetes upgrades accessible via the karbonctl command-line tool. Administrators can trigger a Kubernetes version upgrade on an existing cluster without redeployment, reducing both downtime risk and operational complexity.
Prism Central and Active Directory Integration
Karbon 2.0 deepens integration with Nutanix Prism Central, the unified management plane for Nutanix infrastructure. Specifically, administrators can now leverage an existing Prism Central + Active Directory (AD) configuration to grant read-only Prism user access to Karbon resources.
This allows organisations to extend role-based access control (RBAC) from their existing AD infrastructure into their Kubernetes management layer without managing a separate identity system for Karbon.
Summary of Karbon 2.0 Capabilities
| Feature | Description |
|---|---|
| Air-Gap Support | Run Kubernetes clusters in fully network-isolated environments using a local Docker registry VM |
| One-Click Kubernetes Upgrades | Upgrade Kubernetes version on existing clusters via karbonctl without redeployment |
| Prism Central Integration | Use existing Prism Central + AD setup to manage read-only Karbon user access |
Why This Matters for Enterprise and Regulated Environments
The air-gap capability is a meaningful step toward making Kubernetes viable in sectors where network isolation is non-negotiable. Combined with simplified upgrades and tighter identity management integration, Karbon 2.0 positions Nutanix’s Kubernetes offering more competitively for enterprise customers who have previously been blocked from adopting container orchestration due to connectivity requirements.
For teams already running Nutanix HCI with Prism Central, these additions lower the barrier to adopting and maintaining Kubernetes clusters at scale within their existing operational workflows.