Add code for multiproject GCE Client creation

cmd/glbc/app/clients.go

@@ -78,30 +78,44 @@ func NewKubeConfig(logger klog.Logger) (*rest.Config, error) {
 	return config, nil
 }
 
+// GCEConfString returns the default GCE cluster config file content as a string.
+func GCEConfString(logger klog.Logger) (string, error) {
+	if flags.F.ConfigFilePath == "" {
+		return "", fmt.Errorf("config file path is not specified")
+	}
+
+	logger.Info("Reading config from the specified path", "path", flags.F.ConfigFilePath)
+	configBytes, err := os.ReadFile(flags.F.ConfigFilePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to read config file: %v", err)
+	}
+
+	configString := string(configBytes)
+	logger.V(4).Info("Cloudprovider config file", "config", configString)
+
+	return configString, nil
+}
+
 // NewGCEClient returns a client to the GCE environment. This will block until
 // a valid configuration file can be read.
 func NewGCEClient(logger klog.Logger) *gce.Cloud {
 	var configReader func() io.Reader
 	if flags.F.ConfigFilePath != "" {
-		logger.Info("Reading config from the specified path", "path", flags.F.ConfigFilePath)
-		config, err := os.Open(flags.F.ConfigFilePath)
-		if err != nil {
-			klog.Fatalf("%v", err)
-		}
-		defer config.Close()
-
-		allConfig, err := io.ReadAll(config)
+		allConfig, err := GCEConfString(logger)
 		if err != nil {
-			klog.Fatalf("Error while reading config (%q): %v", flags.F.ConfigFilePath, err)
+			klog.Fatalf("Error getting default cluster GCE config: %v", err)
 		}
-		logger.V(4).Info("Cloudprovider config file", "config", string(allConfig))
 
-		configReader = generateConfigReaderFunc(allConfig)
+		configReader = generateConfigReaderFunc([]byte(allConfig))
 	} else {
 		logger.V(2).Info("No cloudprovider config file provided, using default values")
 		configReader = func() io.Reader { return nil }
 	}
 
+	return GCEClientForConfigReader(configReader, logger)
+}
+
+func GCEClientForConfigReader(configReader func() io.Reader, logger klog.Logger) *gce.Cloud {
 	// Creating the cloud interface involves resolving the metadata server to get
 	// an oauth token. If this fails, the token provider assumes it's not on GCE.
 	// No errors are thrown. So we need to keep retrying till it works because

go.mod

@@ -5,6 +5,7 @@ go 1.22.8
 require (
 	github.com/GoogleCloudPlatform/gke-networking-api v0.1.2-0.20240909212819-4b1bab7c69ea
 	github.com/GoogleCloudPlatform/k8s-cloud-provider v1.32.0
+	github.com/go-ini/ini v1.67.0
 	github.com/go-logr/logr v1.4.2
 	github.com/golang/protobuf v1.5.4
 	github.com/google/go-cmp v0.6.0

go.sum

@@ -34,6 +34,8 @@ github.com/evanphx/json-patch v5.6.0+incompatible h1:jBYDEEiFBPxA0v50tFdvOzQQTCv
 github.com/evanphx/json-patch v5.6.0+incompatible/go.mod h1:50XU6AFN0ol/bzJsmQLiYLvXMP4fmwYFNcr97nuDLSk=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
+github.com/go-ini/ini v1.67.0 h1:z6ZrTEZqSWOTyH2FlglNbNgARyHG8oLW9gMELqKr06A=
+github.com/go-ini/ini v1.67.0/go.mod h1:ByCAeIL28uOIIG0E3PJtZPDL8WnHpFKFOtgjp+3Ies8=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
 github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=

pkg/multiproject/gce/gce.go

@@ -0,0 +1,126 @@
+package gce
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/go-ini/ini"
+	cloudgce "k8s.io/cloud-provider-gcp/providers/gce"
+	"k8s.io/ingress-gce/cmd/glbc/app"
+	v1 "k8s.io/ingress-gce/pkg/apis/clusterslice/v1"
+	"k8s.io/klog/v2"
+)
+
+func init() {
+	// Disable pretty printing for INI files, to match default format of gce.conf.
+	ini.PrettyFormat = false
+	ini.PrettyEqual = true
+	ini.PrettySection = true
+}
+
+// NewGCEForClusterSlice returns a new GCE client for the given project.
+// If clusterSlice is nil, it returns the default cloud associated with the cluster's project.
+// It modifies the default configuration when a clusterSlice is provided.
+func NewGCEForClusterSlice(defaultConfigContent string, clusterSlice *v1.ClusterSlice, logger klog.Logger) (*cloudgce.Cloud, error) {
+	modifiedConfigContent, err := generateConfigForClusterSlice(defaultConfigContent, clusterSlice)
+	if err != nil {
+		return nil, fmt.Errorf("failed to modify config content: %v", err)
+	}
+
+	// Return a new GCE client using the modified configuration content
+	return app.GCEClientForConfigReader(
+		func() io.Reader { return strings.NewReader(modifiedConfigContent) },
+		logger,
+	), nil
+}
+
+func generateConfigForClusterSlice(defaultConfigContent string, clusterSlice *v1.ClusterSlice) (string, error) {
+	if clusterSlice == nil {
+		return defaultConfigContent, nil
+	}
+
+	// Load the config content into an INI file
+	cfg, err := ini.Load([]byte(defaultConfigContent))
+	if err != nil {
+		return "", fmt.Errorf("failed to parse default config content: %w", err)
+	}
+
+	globalSection := cfg.Section("global")
+	if globalSection == nil {
+		return "", fmt.Errorf("global section not found in config")
+	}
+
+	// Update ProjectID
+	projectIDKey := "project-id"
+	globalSection.Key(projectIDKey).SetValue(clusterSlice.Spec.ProjectID)
+
+	// Update TokenURL
+	tokenURLKey := "token-url"
+	tokenURL := globalSection.Key(tokenURLKey).String()
+	projectNumberInt := clusterSlice.Spec.ProjectNumber
+	projectNumberStr := fmt.Sprintf("%d", projectNumberInt)
+	newTokenURL := replaceProjectNumberInTokenURL(tokenURL, projectNumberStr)
+	globalSection.Key(tokenURLKey).SetValue(newTokenURL)
+
+	// Update TokenBody
+	tokenBodyKey := "token-body"
+	tokenBody := globalSection.Key(tokenBodyKey).String()
+	newTokenBody, err := updateTokenProjectNumber(tokenBody, int(projectNumberInt))
+	if err != nil {
+		return "", fmt.Errorf("failed to update TokenBody: %v", err)
+	}
+	globalSection.Key(tokenBodyKey).SetValue(newTokenBody)
+
+	// Update NetworkName and SubnetworkName
+	if clusterSlice.Spec.NetworkConfig != nil {
+		networkNameKey := "network-name"
+		globalSection.Key(networkNameKey).SetValue(clusterSlice.Spec.NetworkConfig.Network)
+
+		subnetworkNameKey := "subnetwork-name"
+		globalSection.Key(subnetworkNameKey).SetValue(clusterSlice.Spec.NetworkConfig.DefaultSubnetwork)
+	}
+
+	// Write the modified config content to a string with custom options
+	var modifiedConfigContent bytes.Buffer
+	_, err = cfg.WriteTo(&modifiedConfigContent)
+	if err != nil {
+		return "", fmt.Errorf("failed to write modified config content: %v", err)
+	}
+
+	return modifiedConfigContent.String(), nil
+}
+
+// replaceProjectNumberInTokenURL replaces the project number in the token URL.
+func replaceProjectNumberInTokenURL(tokenURL string, projectNumber string) string {
+	parts := strings.Split(tokenURL, "/")
+	for i, part := range parts {
+		if part == "projects" && i+1 < len(parts) {
+			parts[i+1] = projectNumber
+			break
+		}
+	}
+	return strings.Join(parts, "/")
+}
+
+func updateTokenProjectNumber(tokenBody string, projectNumber int) (string, error) {
+	var bodyMap map[string]interface{}
+
+	// Unmarshal the JSON string into a map
+	if err := json.Unmarshal([]byte(tokenBody), &bodyMap); err != nil {
+		return "", fmt.Errorf("error unmarshaling TokenBody: %v", err)
+	}
+
+	// Update the "projectNumber" field with the new value
+	bodyMap["projectNumber"] = projectNumber
+
+	// Marshal the map back into a JSON string
+	newTokenBodyBytes, err := json.Marshal(bodyMap)
+	if err != nil {
+		return "", fmt.Errorf("error marshaling TokenBody: %v", err)
+	}
+
+	return string(newTokenBodyBytes), nil
+}