Lower minimum subnets and AZs to 2

EKS docs suggest that the minimum required subnets/AZs is now 2. Also
updated tests and logging that reference the minimum subnets/AZs.

Issue #290

pkg/az/az.go

@@ -12,7 +12,7 @@ import (
 
 const (
 	// DefaultRequiredAvailabilityZones defines the number of required availability zones
-	DefaultRequiredAvailabilityZones = 3
+	DefaultRequiredAvailabilityZones = 2
 )
 
 // SelectionStrategy provides an interface to allow changing the strategy used to

pkg/az/az_test.go

@@ -70,7 +70,7 @@ var _ = Describe("AZ", func() {
 				})
 
 				It("should have returned 3 availability zones", func() {
-					Expect(len(selectedZones)).To(Equal(3))
+					Expect(len(selectedZones)).To(Equal(2))
 				})
 			})
 
@@ -112,7 +112,7 @@ var _ = Describe("AZ", func() {
 				})
 
 				It("should have returned 3 identical availability zones", func() {
-					Expect(len(selectedZones)).To(Equal(3))
+					Expect(len(selectedZones)).To(Equal(2))
 
 					for _, actualZoneName := range selectedZones {
 						Expect(actualZoneName).To(Equal(*expectedZoneName))
@@ -161,7 +161,7 @@ var _ = Describe("AZ", func() {
 			})
 
 			It("should have returned 3 availability zones", func() {
-				Expect(len(selectedZones)).To(Equal(3))
+				Expect(len(selectedZones)).To(Equal(2))
 			})
 
 			It("should have returned none of the zones to avoid", func() {

pkg/eks/api/vpc.go

@@ -65,11 +65,11 @@ func (c *ClusterConfig) ImportSubnet(topology SubnetTopology, az, subnetID strin
 // HasSufficientPublicSubnets validates if there is a sufficient
 // number of public subnets available to create a cluster
 func (c *ClusterConfig) HasSufficientPublicSubnets() bool {
-	return len(c.SubnetIDs(SubnetTopologyPublic)) >= 3
+	return len(c.SubnetIDs(SubnetTopologyPublic)) >= 2
 }
 
 // HasSufficientPrivateSubnets validates if there is a sufficient
 // number of private subnets available to create a cluster
 func (c *ClusterConfig) HasSufficientPrivateSubnets() bool {
-	return len(c.SubnetIDs(SubnetTopologyPrivate)) >= 3
+	return len(c.SubnetIDs(SubnetTopologyPrivate)) >= 2
 }

pkg/kops/kops.go

@@ -68,7 +68,7 @@ func (k *Wrapper) UseVPC(spec *api.ClusterConfig) error {
 	}
 	logger.Debug("subnets = %#v", spec.VPC.Subnets)
 	if !spec.HasSufficientPublicSubnets() {
-		return fmt.Errorf("cannot use VPC from kops cluster with less then 3 subnets")
+		return fmt.Errorf("cannot use VPC from kops cluster with less then 2 subnets")
 	}
 
 	return nil