feat: Add max pods calculations to VPC limits using EKS AMI methodology #619
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This enhancement adds pod capacity fields to the VPC limits file to help EKS
users make informed decisions about instance sizing and networking configuration.
Changes:
- Add MaxPodsSecondaryIPs: Pod capacity in default secondary IP mode
- Add MaxPodsPrefixDelegation: Pod capacity with prefix delegation enabled
- Add MaxPodsRecommended: AWS recommended limit accounting for CPU constraints
- Add CPUCount: vCPU count to understand recommended limit calculations
Implementation:
- Implements EKS AMI max-pods calculation formulas:
* Secondary IP mode: ENIs x (IPs_per_ENI - 1) + 2
* Prefix delegation: ENIs x ((IPs_per_ENI - 1) x 16) + 2
- Applies CPU-based ceiling (110 for <=30 vCPUs, 250 for >30 vCPUs)
- Handles non-Nitro instances correctly (fallback to secondary IP capacity)
Benefits for users:
- Capacity planning: Understand pod density limits before deploying
- Cost optimization: Choose right-sized instances based on actual pod capacity
- Performance tuning: Respect recommended limits to avoid kubelet overload
- Configuration decisions: Evaluate whether prefix delegation is worth enabling
- Troubleshooting: Quickly identify if pod scheduling issues are IP-related
Impact:
- Updates all 1000+ instance types with pod capacity information
- Fixes 80 non-Nitro instances that previously showed 0 for prefix delegation
- Maintains compatibility with Karpenter's weekly codegen workflow
Documentation:
- Enhanced README with detailed field descriptions, formulas, and examples
- Added Benefits for EKS Users section explaining practical value
- Included complete example entry showing calculations for m5.4xlarge
Example entry (m5.4xlarge):
MaxPodsSecondaryIPs: 234, // 8 x (30-1) + 2 = 234
MaxPodsPrefixDelegation: 3714, // 8 x ((30-1) x 16) + 2 = 3,714
MaxPodsRecommended: 110, // min(3714, 110) due to 16 vCPUs
CPUCount: 16,
Contributor
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Can you please add user story where this extra fields are used and where this will be consumed? |
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This enhancement adds pod capacity fields to the VPC limits file to help EKS users make informed decisions about instance sizing and networking configuration.
Issue #, if available:
Description of changes:
Changes:
Implementation:
Benefits for users:
Impact:
Documentation:
Example entry (m5.4xlarge):
MaxPodsSecondaryIPs: 234, // 8 x (30-1) + 2 = 234
MaxPodsPrefixDelegation: 3714, // 8 x ((30-1) x 16) + 2 = 3,714
MaxPodsRecommended: 110, // min(3714, 110) due to 16 vCPUs
CPUCount: 16,
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