func initGKE()

in pkg/gcp/gcp-kubeconfig.go [247:362]
87 lines of code
28 McCabe index (conditional complexity)

func initGKE(ctx context.Context, kc *k8s.K8S) error {
	if kc.Client != nil {
		// Running in-cluster or using kube config
		return nil
	}

	t0 := time.Now()
	var kConfig *kubeconfig.Config
	var err error

	// TODO: attempt to get the config project ID from a label on the workload or project
	// (if metadata servere or CR can provide them)

	kr := kc.Mesh
	configProjectID := kr.ProjectId
	configLocation := kr.ClusterLocation
	configClusterName := kr.ClusterName

	if kr.MeshAddr != nil {
		if kr.MeshAddr.Scheme == "gke" {
			configProjectID = kr.MeshAddr.Host
		} else if kr.MeshAddr.Host == "container.googleapis.com" {
			// Not using the hub resourceLink format:
			//    container.googleapis.com/projects/wlhe-cr/locations/us-central1-c/clusters/asm-cr
			// or the 'selfLink' from GKE list API
			// "https://container.googleapis.com/v1/projects/wlhe-cr/locations/us-west1/clusters/istio"

			configProjectID = kr.MeshAddr.Host
			if len(kr.MeshAddr.Path) > 1 {
				parts := strings.Split(kr.MeshAddr.Path, "/")
				for i := 0 ; i < len(parts); i++ {
					if parts[i] == "projects" && i+1 < len(parts) {
						configProjectID = parts[i+1]
					}
					if parts[i] == "locations" && i+1 < len(parts) {
						configLocation = parts[i+1]
					}
					if parts[i] == "clusters" && i+1 < len(parts) {
						configClusterName = parts[i+1]
					}
				}
			}
		}
	}

	if configProjectID == "" {
		// GCP can't be initialized without a project ID
		return nil
	}

	var cl *Cluster
	if configLocation == "" || configClusterName == "" {
		// ~500ms
		label := "mesh_id"
		// Try to get the region from metadata server. For Cloudrun, this is not the same with the cluster - it may be zonal
		myRegion, _ := RegionFromMetadata()
		if myRegion == "" {
			myRegion = configLocation
		}
		if kr.MeshAddr != nil && kr.MeshAddr.Scheme == "gke" {
			// Explicit mesh config clusters, no label selector ( used for ASM clusters in current project )
			label = ""
		}
		log.Println("Selecting a GKE cluster ", kr.ProjectId, configProjectID, myRegion)
		cll, err := AllClusters(ctx, kr, configProjectID, label, "")
		if err != nil {
			return err
		}

		if len(cll) == 0 {
			return nil // no cluster to use
		}


		cl = findCluster(kc, cll, myRegion, cl)
		// TODO: connect to cluster, find istiod - and keep trying until a working one is found ( fallback )
	} else {
		// Explicit override - user specified the full path to the cluster.
		// ~400 ms
		if mesh.Debug {
			log.Println("Load GKE cluster explicitly", configProjectID, configLocation, configClusterName)
		}
		cl, err = GKECluster(ctx, kr, configProjectID, configLocation, configClusterName)
		if err != nil {
			return err
		}
		if err != nil {
			log.Println("Failed in NewForConfig", kr, err)
			return err
		}
	}

	kr.ProjectId = configProjectID

	kr.TrustDomain = configProjectID + ".svc.id.goog"
	kConfig = cl.KubeConfig
	if kr.ClusterName == "" {
		kr.ClusterName = cl.ClusterName
	}
	if kr.ClusterLocation == "" {
		kr.ClusterLocation = cl.ClusterLocation
	}

	GCPInitTime = time.Since(t0)

	rc, err := restConfig(kConfig)
	if err != nil {
		return err
	}
	kc.Client, err = kubernetes.NewForConfig(rc)
	if err != nil {
		return err
	}

	return nil
}