feat: adds gcp metadata provider support to cloudmeta package

This adds gcp metadata provider support to cloudmeta package.

Fixes: #4128

pkg/cloudmeta/gcp.go

@@ -0,0 +1,50 @@
+// 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) {
+	// 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")
+	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)
+	}
+
+	return parts[len(parts)-1], nil
+}

pkg/cloudmeta/metadata.go

@@ -17,8 +17,12 @@ type InstanceMetadata struct {
 // CloudProvider is enum of supported cloud providers.
 type CloudProvider string
 
-// CloudProviderAWS represents aws provider.
-var CloudProviderAWS CloudProvider = "aws"
+var (
+	// 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 {
@@ -41,9 +45,12 @@ func NewCloudMeta() (*CloudMeta, error) {
 		return nil, err
 	}
 
+	gcpMeta := NewGCPMetadata()
+
 	return &CloudMeta{
 		providers: []CloudMetadataProvider{
 			awsMeta,
+			gcpMeta,
 		},
 		providerTimeout: defaultTimeout,
 	}, nil