aws: set machine pool defaults for EBS volume type

Set the default type EBS volume for machine pools:
- Controlplane, arbiter and worker pool default to gp3 volume.
- Edge pool default to gp2 volume.

The default decision is taken from existing code [0]. This commit just
makes the defaulting earlier.

Reference

[0] https://github.com/openshift/installer/blob/fd5a518e4951510b82705eee8184b3dd4f2723b2/pkg/asset/machines/worker.go#L102-L117

Author: tthvo

pkg/types/aws/defaults/machinepool.go

@@ -0,0 +1,36 @@
+package defaults
+
+import (
+	"github.com/openshift/installer/pkg/types"
+	"github.com/openshift/installer/pkg/types/aws"
+)
+
+// SetMachinePoolDefaults sets the defaults for the platform.
+func SetMachinePoolDefaults(pool *aws.MachinePool, role string) {
+	if pool == nil {
+		return
+	}
+
+	// Set the default volume type for machine pool.
+	// The current default is gp3 for control plane and worker pool.
+	// For edge pool, the current default is gp2.
+	// See: https://github.com/openshift/installer/blob/fd5a518e4951510b82705eee8184b3dd4f2723b2/pkg/asset/machines/worker.go#L102-L117
+	if pool.EC2RootVolume.Type == "" {
+		defaultEBSType := aws.VolumeTypeGp3
+		if role == types.MachinePoolEdgeRoleName {
+			defaultEBSType = aws.VolumeTypeGp2
+		}
+		pool.EC2RootVolume.Type = defaultEBSType
+	}
+}
+
+// Apply sets values from the default machine platform to the machinepool.
+func Apply(defaultMachinePlatform, machinePool *aws.MachinePool) {
+	// Construct a temporary machine pool so we can set the
+	// defaults first, without overwriting the pool-sepcific values,
+	// which have precedence.
+	tempMP := &aws.MachinePool{}
+	tempMP.Set(defaultMachinePlatform)
+	tempMP.Set(machinePool)
+	machinePool.Set(tempMP)
+}

pkg/types/aws/defaults/machinepool_test.go

@@ -0,0 +1,87 @@
+package defaults
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/openshift/installer/pkg/types"
+	"github.com/openshift/installer/pkg/types/aws"
+)
+
+func TestSetMachinePoolDefaults(t *testing.T) {
+	cases := []struct {
+		name     string
+		pool     *aws.MachinePool
+		role     string
+		expected *aws.MachinePool
+	}{
+		{
+			name:     "nil pool",
+			pool:     nil,
+			role:     types.MachinePoolComputeRoleName,
+			expected: nil,
+		},
+		{
+			name: "empty pool - worker pool sets gp3",
+			pool: &aws.MachinePool{},
+			role: types.MachinePoolComputeRoleName,
+			expected: &aws.MachinePool{
+				EC2RootVolume: aws.EC2RootVolume{
+					Type: aws.VolumeTypeGp3,
+				},
+			},
+		},
+		{
+			name: "empty pool - control plane pool sets gp3",
+			pool: &aws.MachinePool{},
+			role: types.MachinePoolControlPlaneRoleName,
+			expected: &aws.MachinePool{
+				EC2RootVolume: aws.EC2RootVolume{
+					Type: aws.VolumeTypeGp3,
+				},
+			},
+		},
+		{
+			name: "empty pool - arbiter pool sets gp3",
+			pool: &aws.MachinePool{},
+			role: types.MachinePoolArbiterRoleName,
+			expected: &aws.MachinePool{
+				EC2RootVolume: aws.EC2RootVolume{
+					Type: aws.VolumeTypeGp3,
+				},
+			},
+		},
+		{
+			name: "empty pool - edge pool sets gp2",
+			pool: &aws.MachinePool{},
+			role: types.MachinePoolEdgeRoleName,
+			expected: &aws.MachinePool{
+				EC2RootVolume: aws.EC2RootVolume{
+					Type: aws.VolumeTypeGp2,
+				},
+			},
+		},
+		{
+			name: "pool with existing volume type - should not override",
+			pool: &aws.MachinePool{
+				EC2RootVolume: aws.EC2RootVolume{
+					Type: aws.VolumeTypeGp2,
+				},
+			},
+			role: types.MachinePoolComputeRoleName,
+			expected: &aws.MachinePool{
+				EC2RootVolume: aws.EC2RootVolume{
+					Type: aws.VolumeTypeGp2,
+				},
+			},
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			SetMachinePoolDefaults(tc.pool, tc.role)
+			assert.Equal(t, tc.expected, tc.pool, "unexpected machine pool defaults")
+		})
+	}
+}

pkg/types/defaults/machinepools.go

@@ -2,6 +2,8 @@ package defaults
 
 import (
 	"github.com/openshift/installer/pkg/types"
+	"github.com/openshift/installer/pkg/types/aws"
+	awsdefaults "github.com/openshift/installer/pkg/types/aws/defaults"
 	"github.com/openshift/installer/pkg/types/azure"
 	azuredefaults "github.com/openshift/installer/pkg/types/azure/defaults"
 	"github.com/openshift/installer/pkg/types/gcp"
@@ -26,6 +28,12 @@ func SetMachinePoolDefaults(p *types.MachinePool, platform *types.Platform) {
 	}
 
 	switch platform.Name() {
+	case aws.Name:
+		if p.Platform.AWS == nil && platform.AWS.DefaultMachinePlatform != nil {
+			p.Platform.AWS = &aws.MachinePool{}
+		}
+		awsdefaults.Apply(platform.AWS.DefaultMachinePlatform, p.Platform.AWS)
+		awsdefaults.SetMachinePoolDefaults(p.Platform.AWS, p.Name)
 	case azure.Name:
 		if p.Platform.Azure == nil && platform.Azure.DefaultMachinePlatform != nil {
 			p.Platform.Azure = &azure.MachinePool{}