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This document covers Radar’s cluster connection behavior. For CLI flags and basic usage, see the README.

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Persistent Configuration

Radar stores configuration in two files under ~/.radar/:

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Config File (~/.radar/config.json)

Persistent defaults for CLI flags. CLI flags always override these values. Managed via the Settings dialog in the UI or PUT /api/config. 
{
  "kubeconfig": "",
  "kubeconfigDirs": [],
  "namespace": "",
  "port": 9280,
  "noBrowser": false,
  "timelineStorage": "memory",
  "timelineDbPath": "~/.radar/timeline.db",
  "historyLimit": 10000,
  "prometheusUrl": "",
  "mcp": true,
  "debugImage": ""
}
All fields are optional - omitted fields use built-in defaults.
FieldDescription
kubeconfigPath to kubeconfig file (same as --kubeconfig)
kubeconfigDirsDirectories containing kubeconfig files (same as --kubeconfig-dir)
namespaceInitial namespace filter
portServer port (default 9280)
noBrowserDon’t auto-open browser
timelineStoragememory or sqlite
timelineDbPathPath to SQLite database
historyLimitMax timeline events to retain
prometheusUrlManual Prometheus/VictoriaMetrics URL - skips auto-discovery. Useful when Prometheus is not in the same cluster or uses a non-standard service name.
mcpEnable/disable MCP server for AI tools (default: enabled)
debugImageImage for ephemeral debug containers and node debug pods (same as --debug-image). Empty = busybox:latest; point at a mirror for air-gapped / private-registry clusters.

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Settings File (~/.radar/settings.json)

User preferences for the UI. Managed via the Settings dialog or PUT /api/settings. 
{
  "theme": "system",
  "pinnedKinds": [
    { "name": "Deployments", "kind": "Deployment", "group": "" }
  ]
}
FieldValuesDescription
themelight, dark, systemUI theme preference
pinnedKindsArray of {name, kind, group}Resource kinds pinned to the sidebar

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Cluster Connection Precedence

Radar connects to Kubernetes clusters using the same configuration sources as kubectl:
PrioritySourceDescription
1--kubeconfig flagExplicit path to kubeconfig file
2KUBECONFIG env var / --kubeconfig-dir flagEither can provide kubeconfig(s); mutually exclusive alternatives
3In-cluster configAutomatic when running inside a Kubernetes pod (KUBERNETES_SERVICE_HOST is set)
4~/.kube/configDefault kubeconfig location

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KUBECONFIG vs In-Cluster Detection

When Radar runs inside a Kubernetes pod, Kubernetes automatically sets the KUBERNETES_SERVICE_HOST environment variable. This normally triggers in-cluster configuration using the pod’s service account credentials. However, explicit kubeconfig takes precedence. If you set KUBECONFIG or pass --kubeconfig, Radar uses that instead of in-cluster config. This allows you to:
  • Run Radar inside a pod but connect to a different cluster
  • Use specific credentials instead of the pod’s service account
  • Test with a custom kubeconfig while developing inside a cluster
Example: Override in-cluster config 
# Inside a pod, connect to a different cluster
export KUBECONFIG=/path/to/other-cluster.yaml
kubectl radar
This behavior matches kubectl and follows the Kubernetes client-go precedence rules.

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Multiple Kubeconfig Files

KUBECONFIG can contain multiple file paths (colon-separated on Linux/macOS, semicolon-separated on Windows). Radar merges these files following Kubernetes conventions: 
export KUBECONFIG=~/.kube/config:~/.kube/staging-config:~/.kube/prod-config
kubectl radar
Alternatively, use --kubeconfig-dir to load all kubeconfig files from a directory: 
kubectl radar --kubeconfig-dir ~/.kube/configs/

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Context Switching

Radar supports switching between Kubernetes contexts at runtime through the UI. Click the context selector in the header to switch between available contexts. When running in-cluster (using the pod’s service account), context switching is disabled.

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Namespace Picker

The header has a namespace picker on the right. Pick a single namespace to focus the view, or All namespaces to see everything you have access to. Cluster-scoped resources (Nodes, Namespaces, PVs, StorageClasses) appear regardless of the pick if your RBAC permits them - they have no namespace to filter on. Namespace-restricted users without their own cluster-scoped RBAC won’t see cluster-scoped sections at all. The pick is a per-user view filter - it doesn’t change anything for other users sharing the same Radar instance. Locally, your pick is remembered per kubeconfig context across restarts. In shared (auth-enabled) deployments the pick lives for the session.