state_transfer

README

Introduction

Each state transfer consists of 3 components.

• A transfer utility such as rclone or rsync
• A transport used to secure traffic between clusters
• An endpoint type for exposing the server/source side for transfer

Trasfer

Currently rsync and rclone are available.

Transport

Two transports are available.

Null

The null transport is intended for any potential future options that provide their own encryption between client and server. It may also be useful for troubleshooting, but shouldn't be used with unencrypted protocols with sensitive data.

Stunnel

Stunnel is a proxy that provides TLS encryption without having to change existing clients and servers.

Endpoint

Route

Routes are available and commonly used in openshift clusters

Load Balancer

An alternative to routes that will work with other Kubernetes implementations

Compatibility Matrix

Transfer	Transport	Endpoint	State
rclone	null	load balancer	functional but inseure
		route	functional but insecure
	stunnel	load balancer	functional
		route	functional
rsync	null	load balancer	functional but inseure
		route	nonfunctional
	stunnel	load balancer	functional
		route	functional

TODO

• Implement check for clients / servers to ensure pods come up and in the case of servers are ready to send data.
• Implement check for load balancers to resolve
• Look into nodePort as an alternative to LB and route
• Implement functions to tear down servers and clients when the transfer is complete

The lack of progress checks do not cripple functionality, but the client side may error serveral times while servers come up and hostnames become resolvable, which isn't very pretty.

Documentation

Overview

Example (GetFromCreatedObjects)

This example shows how to get the endpoint and transport objects for creating the transfer after endpoint and transport are created in previous reconcile attempt

package main

import (
	"context"
	"log"
	"time"

	"k8s.io/apimachinery/pkg/types"

	"github.com/konveyor/crane-lib/state_transfer/endpoint/route"
	"github.com/konveyor/crane-lib/state_transfer/meta"

	"github.com/konveyor/crane-lib/state_transfer/transfer"
	"github.com/konveyor/crane-lib/state_transfer/transfer/rclone"
	"github.com/konveyor/crane-lib/state_transfer/transport"
	"github.com/konveyor/crane-lib/state_transfer/transport/stunnel"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/rest"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

var (
	srcCfg       = &rest.Config{}
	destCfg      = &rest.Config{}
	srcNamespace = "src-namespace"
	srcPVC       = "example-pvc"
)

func main() {
	srcClient, err := client.New(srcCfg, client.Options{Scheme: runtime.NewScheme()})
	if err != nil {
		log.Fatal(err, "unable to create source client")
	}

	destClient, err := client.New(destCfg, client.Options{Scheme: runtime.NewScheme()})
	if err != nil {
		log.Fatal(err, "unable to create destination client")
	}

	// set up the PVC on destination to receive the data
	pvc := &corev1.PersistentVolumeClaim{}
	err = srcClient.Get(context.TODO(), client.ObjectKey{Namespace: srcNamespace, Name: srcPVC}, pvc)
	if err != nil {
		log.Fatal(err, "unable to get source PVC")
	}

	destPVC := pvc.DeepCopy()

	pvcList, err := transfer.NewFilesystemPVCPairList(
		transfer.NewPVCPair(pvc, destPVC),
	)
	if err != nil {
		log.Fatal(err, "invalid pvc list")
	}

	e, err := route.GetEndpointFromKubeObjects(destClient, types.NamespacedName{Namespace: srcNamespace, Name: srcPVC})
	if err != nil {
		log.Fatal(err, "error getting route endpoint")
	}

	nnPair := meta.NewNamespacedPair(
		types.NamespacedName{Namespace: srcNamespace, Name: srcPVC},
		types.NamespacedName{Namespace: srcNamespace, Name: srcPVC},
	)
	s, err := stunnel.GetTransportFromKubeObjects(srcClient, destClient, "fs", nnPair, e, &transport.Options{})
	if err != nil {
		log.Fatal(err, "error getting stunnel transport")
	}

	pvcList, err = transfer.NewFilesystemPVCPairList(
		transfer.NewPVCPair(pvc, nil),
	)
	if err != nil {
		log.Fatal(err, "invalid pvc list")
	}

	// Create Rclone Transfer Pod
	t, err := rclone.NewTransfer(s, e, srcClient, destClient, pvcList)
	if err != nil {
		log.Fatal(err, "errror creating rclone transfer")
	}
	err = transfer.CreateServer(t)
	if err != nil {
		log.Fatal(err, "error creating rclone server")
	}

	// check if the server is healthy before creating the client
	_ = wait.PollUntil(time.Second*5, func() (done bool, err error) {
		isHealthy, err := t.IsServerHealthy(destClient)
		if err != nil {
			log.Println(err, "unable to check server health, retrying...")
			return false, nil
		}
		return isHealthy, nil
	}, make(<-chan struct{}))

	// Create Rclone Client Pod
	err = transfer.CreateClient(t)
	if err != nil {
		log.Fatal(err, "error creating rclone client")
	}

	// TODO: check if the client is completed
}

Index

• Constants
• func QuiesceApplications(cfg *rest.Config, ns string) error
• func UnQuiesceApplications(c client.Client, ns string) error

Examples

• Package (GetFromCreatedObjects)

Constants

const (
	NodeSelectorAnnotation = "migration.openshift.io/preQuiesceNodeSelector"
	QuiesceNodeSelector    = "migration.openshift.io/quiesceDaemonSet"
	ReplicasAnnotation     = "migration.openshift.io/preQuiesceReplicas"
	SuspendAnnotation      = "migration.openshift.io/preQuiesceSuspend"
)

Functions

func QuiesceApplications

func QuiesceApplications(cfg *rest.Config, ns string) error

Quiesce applications on source cluster

func UnQuiesceApplications

func UnQuiesceApplications(c client.Client, ns string) error