Fails when KUBECONFIG contains multiple colon-separated paths

[permyakovsv]

kn func fails when KUBECONFIG contains multiple colon-separated paths

Describe the bug

kn func commands that require cluster access (e.g., deploy, list, invoke) fail with an ErrInvalidKubeconfig error when the KUBECONFIG environment variable is set to a colon-separated list of paths — which is standard Kubernetes behavior supported by kubectl and client-go.

Expected behavior

kn func should accept a KUBECONFIG value with multiple colon-separated paths (e.g., ~/.kube/config:/other/kubeconfig) the same way kubectl and other Kubernetes tooling does.

Actual behavior

The command fails immediately with an error like:

Error: invalid kubeconfig: kubeconfig file does not exist at path: /home/user/.kube/config:/other/kubeconfig

Possible root cause

validateKubeconfigFile() in pkg/knative/client.go reads the KUBECONFIG env var and passes the entire string directly to os.Stat(), treating it as a single file path:

func validateKubeconfigFile() error {
    kubeconfigPath := os.Getenv("KUBECONFIG")
    if kubeconfigPath == "" {
        return nil
    }
    if _, err := os.Stat(kubeconfigPath); os.IsNotExist(err) {
        return fmt.Errorf("%w: kubeconfig file does not exist at path: %s", fn.ErrInvalidKubeconfig, kubeconfigPath)
    }
    return nil
}

When KUBECONFIG=/path/a:/path/b, os.Stat("/path/a:/path/b") fails because /path/a:/path/b is not a valid single path.

Steps to reproduce

1. Set KUBECONFIG to multiple paths: export KUBECONFIG=~/.kube/config:/path/to/second/config
2. Run any cluster-bound command: kn func list
3. Observe the ErrInvalidKubeconfig error.

Environment

• kn func version: v0.48.3
• OS: macOS 26.4
• KUBECONFIG value format: multiple colon-separated paths