feat: adds gcp metadata provider support to cloudmeta package

pkg/cloudmeta/gcp.go

@@ -0,0 +1,66 @@
+// Copyright (C) 2024 ScyllaDB
+
+package cloudmeta
+
+import (
+	"context"
+	"strings"
+
+	"cloud.google.com/go/compute/metadata"
+	"github.com/pkg/errors"
+)
+
+// gcpMetadata is a wrapper around gcp metadata client.
+type gcpMetadata struct {
+	meta *metadata.Client
+}
+
+// newGCPMetadata returns gcp metadata provider.
+func newGCPMetadata() *gcpMetadata {
+	return &gcpMetadata{
+		meta: metadata.NewClient(nil),
+	}
+}
+
+// Metadata returns InstanceMetadata from gcp if available.
+func (gcp *gcpMetadata) Metadata(ctx context.Context) (InstanceMetadata, error) {
+	machineType, err := gcp.getMachineType(ctx)
+	if err != nil {
+		return InstanceMetadata{}, errors.Wrap(err, "gcp.meta.GetWithContext")
+	}
+	return InstanceMetadata{
+		CloudProvider: CloudProviderGCP,
+		InstanceType:  machineType,
+	}, nil
+}
+
+func (gcp *gcpMetadata) getMachineType(ctx context.Context) (string, error) {
+	machineTypeResp, err := gcp.meta.GetWithContext(ctx, "instance/machine-type")
+	if err != nil {
+		return "", errors.Wrap(err, "gcp.meta.GetWithContext")
+	}
+
+	machineType, err := parseMachineTypeResponse(machineTypeResp)
+	if err != nil {
+		return "", err
+	}
+
+	return machineType, nil
+}
+
+// The machine type for this VM. This value has the following format: projects/PROJECT_NUM/machineTypes/MACHINE_TYPE.
+// See https://cloud.google.com/compute/docs/metadata/predefined-metadata-keys#instance-metadata.
+func parseMachineTypeResponse(resp string) (string, error) {
+	errUnexpectedFormat := errors.Errorf("unexpected machineType response format: %s", resp)
+
+	parts := strings.Split(resp, "/")
+	if len(parts) != 4 {
+		return "", errUnexpectedFormat
+	}
+
+	if parts[2] != "machineTypes" {
+		return "", errUnexpectedFormat
+	}
+
+	return parts[3], nil
+}

pkg/cloudmeta/gcp_test.go

@@ -0,0 +1,67 @@
+// Copyright (C) 2024 ScyllaDB
+
+package cloudmeta
+
+import "testing"
+
+func TestParseMachineTypeResponse(t *testing.T) {
+	testCases := []struct {
+		name                string
+		machineTypeResponse string
+
+		expectedErr bool
+		expected    string
+	}{
+		{
+			name:                "everything is fine",
+			machineTypeResponse: "projects/project1/machineTypes/machineType1",
+
+			expectedErr: false,
+			expected:    "machineType1",
+		},
+		{
+			name:                "new response part is added",
+			machineTypeResponse: "projects/project1/zone/zone1/machineTypes/machineType1",
+
+			expectedErr: true,
+			expected:    "",
+		},
+		{
+			name:                "new response part is added after machineTypes part",
+			machineTypeResponse: "projects/project1/machineTypes/machineType1/zones/zone1",
+
+			expectedErr: true,
+			expected:    "",
+		},
+		{
+			name:                "parts are mixed up",
+			machineTypeResponse: "machineTypes/machineType1/projects/project1",
+
+			expectedErr: true,
+			expected:    "",
+		},
+		{
+			name:                "empty response",
+			machineTypeResponse: "",
+
+			expectedErr: true,
+			expected:    "",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			machineType, err := parseMachineTypeResponse(tc.machineTypeResponse)
+			if tc.expectedErr && err == nil {
+				t.Fatalf("expected err, but got %v", err)
+			}
+			if !tc.expectedErr && err != nil {
+				t.Fatalf("unexpected err: %v", err)
+			}
+
+			if tc.expected != machineType {
+				t.Fatalf("machineType(%s) != expected(%s)", machineType, tc.expected)
+			}
+		})
+	}
+}

pkg/cloudmeta/metadata.go

@@ -19,8 +19,12 @@ type InstanceMetadata struct {
 // CloudProvider is enum of supported cloud providers.
 type CloudProvider string
 
-// CloudProviderAWS represents aws provider.
-var CloudProviderAWS CloudProvider = "aws"
+const (
+	// CloudProviderAWS represents aws provider.
+	CloudProviderAWS CloudProvider = "aws"
+	// CloudProviderGCP represents gcp provider.
+	CloudProviderGCP CloudProvider = "gcp"
+)
 
 // CloudMetadataProvider interface that each metadata provider should implement.
 type CloudMetadataProvider interface {
@@ -43,9 +47,12 @@ func NewCloudMeta() (*CloudMeta, error) {
 		return nil, err
 	}
 
+	gcpMeta := newGCPMetadata()
+
 	return &CloudMeta{
 		providers: []CloudMetadataProvider{
 			awsMeta,
+			gcpMeta,
 		},
 		providerTimeout: defaultTimeout,
 	}, nil