kubernetes/kops · error

error parsing CIDR %q: %v

Error message

error parsing CIDR %q: %v

What it means

CIDRMap.Allocate carves subnets out of a parent range given as a CIDR string. The `from` argument must parse via net.ParseCIDR; if it doesn't, allocation cannot start and this error quotes the invalid range. Like MarkInUse it validates the same input class but under the Allocate entry point.

Source

Thrown at pkg/util/subnet/cidrmap.go:84

				newHigh++
			}
		}
		binary.BigEndian.PutUint64(ip[0:8], newHigh)
		binary.BigEndian.PutUint64(ip[8:16], newLow)
	}
	return nil
}

func duplicateIP(src net.IP) net.IP {
	ret := make(net.IP, len(src))
	copy(ret, src)
	return ret
}

func (c *CIDRMap) Allocate(from string, mask net.IPMask) (*net.IPNet, error) {
	_, cidr, err := net.ParseCIDR(from)
	if err != nil {
		return nil, fmt.Errorf("error parsing CIDR %q: %v", from, err)
	}

	var candidate net.IPNet
	candidate.Mask = mask
	candidate.IP = duplicateIP(cidr.IP)

	for {
		// Note we increment first, so we won't ever use the first range (e.g. 10.0.0.0/n)
		if err := incrementIP(candidate.IP, mask); err != nil {
			return nil, err
		}

		// Check we're still in the range we're drawing from
		if !cidrsOverlap(cidr, &candidate) {
			klog.Infof("candidate CIDR %v is not in CIDR %v", candidate, cidr)
			break
		}

View on GitHub (pinned to 4c8573c808)

Solutions

1. Correct the base CIDR string to valid notation (e.g. 10.0.0.0/16) and retry
2. Validate the value before calling Allocate (net.ParseCIDR in a pre-check)
3. Fix the cluster spec field supplying this value (kops edit cluster) and update the cluster

Example fix

// before
subnet, err := cidrMap.Allocate("10.0.0.0/33", mask)
// after
subnet, err := cidrMap.Allocate("10.0.0.0/16", mask)

if _, _, err := net.ParseCIDR(from); err != nil {
	return nil, fmt.Errorf("base CIDR %q invalid: %w", from, err)
}

func isCIDR(s string) bool {
	_, _, err := net.ParseCIDR(s)
	return err == nil
}

When it happens

Trigger: Calling Allocate with a malformed `from` base CIDR — e.g. "10.0.0.0" without /mask, an out-of-range prefix like /33, or IPv6 text where IPv4 is expected — typically from subnet/cidr allocation during cluster creation.

Common situations: Cluster spec with a bad nonMasqueradeCIDR or subnet base range, typo'd YAML values, or programmatically built CIDR strings that were never validated.

Related errors

• error parsing network cidr %q: %v
• invalid subnet %q CIDR: %q
• subnet %q has unexpected CIDR %q
• linode VPC requires at least one subnet
• linode subnet %q requires a CIDR

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/ed59915cd840837c. Report an issue: GitHub.