feat: ipv6 small subnets

Set a limit of 32 pods per node in your Kubernetes cluster. Some cloud providers offer a /123 IPv6 subnet for nodes, which is typically sufficient for most use cases. Signed-off-by: Serge Logvinov <[email protected]>
siderolabs · Oct 21, 2024 · 82009ed · 82009ed
1 parent 68d4133
commit 82009ed
Show file tree

Hide file tree

Showing 2 changed files with 16 additions and 2 deletions.
diff --git a/pkg/nodeipam/ipam/cloud_allocator.go b/pkg/nodeipam/ipam/cloud_allocator.go
@@ -628,8 +628,10 @@ func (r *cloudAllocator) addCIDRSet(cidr string) error {
 		}
 
 		mask = 80
-	case mask > 120:
+	case mask > 123:
 		return fmt.Errorf("CIDRv6 is too small: %v", subnet.String())
+	case mask > 119:
+		break
 	default:
 		mask += 16
 	}

diff --git a/pkg/nodeipam/ipam/cloud_allocator_test.go b/pkg/nodeipam/ipam/cloud_allocator_test.go
@@ -65,11 +65,23 @@ func TestAddCIDRSet(t *testing.T) {
 			expectedClusterCIDR: netip.MustParsePrefix("2000::aaaa:bbbb:cccc:0/112"),
 		},
 		{
-			name:                "CIDRv6 with mask size 120",
+			name:                "CIDRv6 with mask size 120, 256 pods",
 			cidr:                "2000::aaaa:bbbb:cccc:123/120",
 			expectedSize:        1,
 			expectedClusterCIDR: netip.MustParsePrefix("2000::aaaa:bbbb:cccc:100/120"),
 		},
+		{
+			name:                "CIDRv6 with mask size 122, 64 pods",
+			cidr:                "2000::aaaa:bbbb:cccc:123/122",
+			expectedSize:        1,
+			expectedClusterCIDR: netip.MustParsePrefix("2000::aaaa:bbbb:cccc:100/122"),
+		},
+		{
+			name:                "CIDRv6 with mask size 123, 32 pods",
+			cidr:                "2000::aaaa:bbbb:cccc:123/123",
+			expectedSize:        1,
+			expectedClusterCIDR: netip.MustParsePrefix("2000::aaaa:bbbb:cccc:120/123"),
+		},
 		{
 			name:          "CIDRv6 with mask size 124",
 			cidr:          "2000::aaaa:bbbb:cccc:123/124",