feat: adds gcp metadata provider support to cloudmeta package

pkg/cloudmeta/gcp.go

@@ -35,16 +35,32 @@ func (gcp *gcpMetadata) Metadata(ctx context.Context) (InstanceMetadata, error)
 }
 
 func (gcp *gcpMetadata) getMachineType(ctx context.Context) (string, error) {
-	// The machine type for this VM. This value has the following format: projects/PROJECT_NUM/machineTypes/MACHINE_TYPE.
-	machineType, err := gcp.meta.GetWithContext(ctx, "instance/machine-type")
+	machineTypeResp, err := gcp.meta.GetWithContext(ctx, "instance/machine-type")
 	if err != nil {
 		return "", errors.Wrap(err, "gcp.meta.GetWithContext")
 	}
 
-	parts := strings.Split(machineType, "/")
-	if len(parts) < 2 {
-		return "", errors.Errorf("unexpected machine-type format: %s", machineType)
+	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.SplitN(resp, "/", 4)
+	if len(parts) != 4 {
+		return "", errUnexpectedFormat
+	}
+
+	if parts[2] != "machineType" {
+		return "", errUnexpectedFormat
 	}
 
-	return parts[len(parts)-1], nil
+	return parts[3], nil
 }

pkg/cloudmeta/gcp_test.go

@@ -0,0 +1,60 @@
+// 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/machineType/machineType1",
+
+			expectedErr: false,
+			expected:    "machineType1",
+		},
+		{
+			name:                "new response part is added",
+			machineTypeResponse: "projects/project1/zone/zone1/machineType/machineType1",
+
+			expectedErr: true,
+			expected:    "",
+		},
+		{
+			name:                "parts are mixed up",
+			machineTypeResponse: "machineType/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)
+			}
+		})
+	}
+}