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bug: disallow updating apiServerLB private IP after AzureCluster creation #5827

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bug: disallow updating apiServerLB private IP after AzureCluster creation #5827

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7f8e5a0
bug: forbid APIServerILB private IP mutation
3mbe Aug 18, 2025
8151715
ci: fix lint errors (gocritic 'else if') to unblock CI
3mbe Aug 18, 2025
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26 changes: 19 additions & 7 deletions api/v1beta1/azurecluster_validation.go
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Original file line number Diff line number Diff line change
Expand Up @@ -433,12 +433,19 @@ func validateAPIServerLB(lb *LoadBalancerSpec, old *LoadBalancerSpec, cidrs []st
if err := validateInternalLBIPAddress(privateIP, cidrs, fldPath.Child("frontendIPConfigs").Index(0).Child("privateIP")); err != nil {
allErrs = append(allErrs, err)
}
} else {
// API Server LB should not have a Private IP if APIServerILB feature is disabled.
if privateIPCount > 0 {
allErrs = append(allErrs, field.Forbidden(fldPath.Child("frontendIPConfigs").Index(0).Child("privateIP"),
"Public Load Balancers cannot have a Private IP"))

if old != nil && len(old.FrontendIPs) > 0 && len(lb.FrontendIPs) > 0 {
oldIP := old.FrontendIPs[0].PrivateIPAddress
newIP := lb.FrontendIPs[0].PrivateIPAddress
if newIP != oldIP {
allErrs = append(allErrs, field.Forbidden(fldPath.Child("frontendIPConfigs").Index(0).Child("privateIP"),
"field is immutable"))
}
}
} else if privateIPCount > 0 {
// API Server LB should not have a Private IP if APIServerILB feature is disabled.
allErrs = append(allErrs, field.Forbidden(fldPath.Child("frontendIPConfigs").Index(0).Child("privateIP"),
"Public Load Balancers cannot have a Private IP"))
}
}

Expand All @@ -457,8 +464,13 @@ func validateAPIServerLB(lb *LoadBalancerSpec, old *LoadBalancerSpec, cidrs []st
allErrs = append(allErrs, err)
}

if old != nil && len(old.FrontendIPs) != 0 && old.FrontendIPs[0].PrivateIPAddress != lb.FrontendIPs[0].PrivateIPAddress {
allErrs = append(allErrs, field.Forbidden(fldPath.Child("name"), "API Server load balancer private IP should not be modified after AzureCluster creation."))
if old != nil && len(old.FrontendIPs) > 0 && len(lb.FrontendIPs) > 0 {
oldIP := old.FrontendIPs[0].PrivateIPAddress
newIP := lb.FrontendIPs[0].PrivateIPAddress
if newIP != oldIP {
allErrs = append(allErrs, field.Forbidden(fldPath.Child("frontendIPConfigs").Index(0).Child("privateIP"),
"field is immutable"))
}
}
}
}
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63 changes: 63 additions & 0 deletions api/v1beta1/azurecluster_validation_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1285,6 +1285,69 @@ func TestValidateAPIServerLB(t *testing.T) {
Detail: "Internal LB IP address needs to be in control plane subnet range ([10.0.0.0/24 10.1.0.0/24])",
},
},
{
name: "public LB + APIServerILB: changing private IP after creation is forbidden",
featureGate: feature.APIServerILB,
old: &LoadBalancerSpec{
LoadBalancerClassSpec: LoadBalancerClassSpec{Type: Public, SKU: SKUStandard},
Name: "my-public-lb",
FrontendIPs: []FrontendIP{
{
Name: "ip-priv",
FrontendIPClass: FrontendIPClass{PrivateIPAddress: "10.0.0.10"},
},
{
Name: "ip-pub",
PublicIP: &PublicIPSpec{Name: "pub", DNSName: "pub"},
},
},
},
lb: &LoadBalancerSpec{
LoadBalancerClassSpec: LoadBalancerClassSpec{Type: Public, SKU: SKUStandard},
Name: "my-public-lb",
FrontendIPs: []FrontendIP{
{
Name: "ip-priv",
FrontendIPClass: FrontendIPClass{PrivateIPAddress: "10.0.0.11"},
},
{
Name: "ip-pub",
PublicIP: &PublicIPSpec{Name: "pub", DNSName: "pub"},
},
},
},
cpCIDRS: []string{"10.0.0.0/24"},
wantErr: true,
expectedErr: field.Error{
Type: "FieldValueForbidden",
Field: "apiServerLB.frontendIPConfigs[0].privateIP",
Detail: "field is immutable",
},
},
{
name: "internal LB: changing private IP after creation is forbidden",
old: &LoadBalancerSpec{
LoadBalancerClassSpec: LoadBalancerClassSpec{Type: Internal, SKU: SKUStandard},
Name: "my-private-lb",
FrontendIPs: []FrontendIP{
{Name: "ip-1", FrontendIPClass: FrontendIPClass{PrivateIPAddress: "10.1.0.3"}},
},
},
lb: &LoadBalancerSpec{
LoadBalancerClassSpec: LoadBalancerClassSpec{Type: Internal, SKU: SKUStandard},
Name: "my-private-lb",
FrontendIPs: []FrontendIP{
{Name: "ip-1", FrontendIPClass: FrontendIPClass{PrivateIPAddress: "10.1.0.4"}},
},
},
cpCIDRS: []string{"10.1.0.0/24"},
wantErr: true,
expectedErr: field.Error{
Type: "FieldValueForbidden",
Field: "apiServerLB.frontendIPConfigs[0].privateIP",
Detail: "field is immutable",
},
},
}

for _, test := range testcases {
Expand Down
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