kubernetes/pkg/api/validation/validation.go

/*
Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package validation

import (
	"fmt"
	"strings"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	errs "github.com/GoogleCloudPlatform/kubernetes/pkg/api/errors"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/resource"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/capabilities"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"

	"github.com/golang/glog"
)

const qualifiedNameErrorMsg string = "must match regex [" + util.DNS1123SubdomainFmt + " / ] " + util.DNS1123LabelFmt
const cIdentifierErrorMsg string = "must match regex " + util.CIdentifierFmt
const isNegativeErrorMsg string = "value must not be negative"

func intervalErrorMsg(lo, hi int) string {
	return fmt.Sprintf("must be greater than %d and less than %d", lo, hi)
}

var dnsSubdomainErrorMsg string = fmt.Sprintf("must have at most %d characters and match regex %s", util.DNS1123SubdomainMaxLength, util.DNS1123SubdomainFmt)
var dnsLabelErrorMsg string = fmt.Sprintf("must have at most %d characters and match regex %s", util.DNS1123LabelMaxLength, util.DNS1123LabelFmt)
var dns952LabelErrorMsg string = fmt.Sprintf("must have at most %d characters and match regex %s", util.DNS952LabelMaxLength, util.DNS952LabelFmt)
var pdPartitionErrorMsg string = intervalErrorMsg(0, 255)
var portRangeErrorMsg string = intervalErrorMsg(0, 65536)

// ValidateLabels validates that a set of labels are correctly defined.
func ValidateLabels(labels map[string]string, field string) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	for k := range labels {
		if !util.IsQualifiedName(k) {
			allErrs = append(allErrs, errs.NewFieldInvalid(field, k, qualifiedNameErrorMsg))
		}
	}
	return allErrs
}

// ValidateAnnotations validates that a set of annotations are correctly defined.
func ValidateAnnotations(annotations map[string]string, field string) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	for k := range annotations {
		if !util.IsQualifiedName(strings.ToLower(k)) {
			allErrs = append(allErrs, errs.NewFieldInvalid(field, k, qualifiedNameErrorMsg))
		}
	}
	return allErrs
}

// ValidateNameFunc validates that the provided name is valid for a given resource type.
// Not all resources have the same validation rules for names. Prefix is true if the
// name will have a value appended to it.
type ValidateNameFunc func(name string, prefix bool) (bool, string)

// maskTrailingDash replaces the final character of a string with a subdomain safe
// value if is a dash.
func maskTrailingDash(name string) string {
	if strings.HasSuffix(name, "-") {
		return name[:len(name)-2] + "a"
	}
	return name
}

// ValidatePodName can be used to check whether the given pod name is valid.
// Prefix indicates this name will be used as part of generation, in which case
// trailing dashes are allowed.
func ValidatePodName(name string, prefix bool) (bool, string) {
	return nameIsDNSSubdomain(name, prefix)
}

// ValidateReplicationControllerName can be used to check whether the given replication
// controller name is valid.
// Prefix indicates this name will be used as part of generation, in which case
// trailing dashes are allowed.
func ValidateReplicationControllerName(name string, prefix bool) (bool, string) {
	return nameIsDNSSubdomain(name, prefix)
}

// ValidateServiceName can be used to check whether the given service name is valid.
// Prefix indicates this name will be used as part of generation, in which case
// trailing dashes are allowed.
func ValidateServiceName(name string, prefix bool) (bool, string) {
	return nameIsDNS952Label(name, prefix)
}

// ValidateNodeName can be used to check whether the given node name is valid.
// Prefix indicates this name will be used as part of generation, in which case
// trailing dashes are allowed.
func ValidateNodeName(name string, prefix bool) (bool, string) {
	return nameIsDNSSubdomain(name, prefix)
}

// ValidateNamespaceName can be used to check whether the given namespace name is valid.
// Prefix indicates this name will be used as part of generation, in which case
// trailing dashes are allowed.
func ValidateNamespaceName(name string, prefix bool) (bool, string) {
	return nameIsDNSSubdomain(name, prefix)
}

// nameIsDNSSubdomain is a ValidateNameFunc for names that must be a DNS subdomain.
func nameIsDNSSubdomain(name string, prefix bool) (bool, string) {
	if prefix {
		name = maskTrailingDash(name)
	}
	if util.IsDNSSubdomain(name) {
		return true, ""
	}
	return false, dnsSubdomainErrorMsg
}

// nameIsDNS952Label is a ValidateNameFunc for names that must be a DNS 952 label.
func nameIsDNS952Label(name string, prefix bool) (bool, string) {
	if prefix {
		name = maskTrailingDash(name)
	}
	if util.IsDNS952Label(name) {
		return true, ""
	}
	return false, dns952LabelErrorMsg
}

// ValidateObjectMeta validates an object's metadata on creation. It expects that name generation has already
// been performed.
func ValidateObjectMeta(meta *api.ObjectMeta, requiresNamespace bool, nameFn ValidateNameFunc) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	if len(meta.GenerateName) != 0 {
		if ok, qualifier := nameFn(meta.GenerateName, true); !ok {
			allErrs = append(allErrs, errs.NewFieldInvalid("generateName", meta.GenerateName, qualifier))
		}
	}
	// if the generated name validates, but the calculated value does not, it's a problem with generation, and we
	// report it here. This may confuse users, but indicates a programming bug and still must be validated.
	if len(meta.Name) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("name", meta.Name))
	} else {
		if ok, qualifier := nameFn(meta.Name, false); !ok {
			allErrs = append(allErrs, errs.NewFieldInvalid("name", meta.Name, qualifier))
		}
	}

	if requiresNamespace {
		if len(meta.Namespace) == 0 {
			allErrs = append(allErrs, errs.NewFieldRequired("namespace", meta.Namespace))
		} else if !util.IsDNSSubdomain(meta.Namespace) {
			allErrs = append(allErrs, errs.NewFieldInvalid("namespace", meta.Namespace, dnsSubdomainErrorMsg))
		}
	} else {
		if len(meta.Namespace) != 0 {
			allErrs = append(allErrs, errs.NewFieldInvalid("namespace", meta.Namespace, "namespace is not allowed on this type"))
		}
	}
	allErrs = append(allErrs, ValidateLabels(meta.Labels, "labels")...)
	allErrs = append(allErrs, ValidateAnnotations(meta.Annotations, "annotations")...)

	return allErrs
}

// ValidateObjectMetaUpdate validates an object's metadata when updated
func ValidateObjectMetaUpdate(old, meta *api.ObjectMeta) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	// in the event it is left empty, set it, to allow clients more flexibility
	if len(meta.UID) == 0 {
		meta.UID = old.UID
	}
	if meta.CreationTimestamp.IsZero() {
		meta.CreationTimestamp = old.CreationTimestamp
	}

	if old.Name != meta.Name {
		allErrs = append(allErrs, errs.NewFieldInvalid("name", meta.Name, "field is immutable"))
	}
	if old.Namespace != meta.Namespace {
		allErrs = append(allErrs, errs.NewFieldInvalid("namespace", meta.Namespace, "field is immutable"))
	}
	if old.UID != meta.UID {
		allErrs = append(allErrs, errs.NewFieldInvalid("uid", meta.UID, "field is immutable"))
	}
	if old.CreationTimestamp != meta.CreationTimestamp {
		allErrs = append(allErrs, errs.NewFieldInvalid("creationTimestamp", meta.CreationTimestamp, "field is immutable"))
	}

	allErrs = append(allErrs, ValidateLabels(meta.Labels, "labels")...)
	allErrs = append(allErrs, ValidateAnnotations(meta.Annotations, "annotations")...)

	return allErrs
}

func validateVolumes(volumes []api.Volume) (util.StringSet, errs.ValidationErrorList) {
	allErrs := errs.ValidationErrorList{}

	allNames := util.StringSet{}
	for i, vol := range volumes {
		el := validateSource(&vol.Source).Prefix("source")
		if len(vol.Name) == 0 {
			el = append(el, errs.NewFieldRequired("name", vol.Name))
		} else if !util.IsDNSLabel(vol.Name) {
			el = append(el, errs.NewFieldInvalid("name", vol.Name, dnsLabelErrorMsg))
		} else if allNames.Has(vol.Name) {
			el = append(el, errs.NewFieldDuplicate("name", vol.Name))
		}
		if len(el) == 0 {
			allNames.Insert(vol.Name)
		} else {
			allErrs = append(allErrs, el.PrefixIndex(i)...)
		}
	}
	return allNames, allErrs
}

func validateSource(source *api.VolumeSource) errs.ValidationErrorList {
	numVolumes := 0
	allErrs := errs.ValidationErrorList{}
	if source.HostPath != nil {
		numVolumes++
		allErrs = append(allErrs, validateHostPath(source.HostPath).Prefix("hostPath")...)
	}
	if source.EmptyDir != nil {
		numVolumes++
		// EmptyDirs have nothing to validate
	}
	if source.GitRepo != nil {
		numVolumes++
		allErrs = append(allErrs, validateGitRepo(source.GitRepo).Prefix("gitRepo")...)
	}
	if source.GCEPersistentDisk != nil {
		numVolumes++
		allErrs = append(allErrs, validateGCEPersistentDisk(source.GCEPersistentDisk).Prefix("persistentDisk")...)
	}
	if numVolumes != 1 {
		allErrs = append(allErrs, errs.NewFieldInvalid("", source, "exactly 1 volume type is required"))
	}
	return allErrs
}

func validateHostPath(hostDir *api.HostPath) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if hostDir.Path == "" {
		allErrs = append(allErrs, errs.NewFieldRequired("path", hostDir.Path))
	}
	return allErrs
}

func validateGitRepo(gitRepo *api.GitRepo) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if gitRepo.Repository == "" {
		allErrs = append(allErrs, errs.NewFieldRequired("repository", gitRepo.Repository))
	}
	return allErrs
}

func validateGCEPersistentDisk(PD *api.GCEPersistentDisk) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if PD.PDName == "" {
		allErrs = append(allErrs, errs.NewFieldRequired("pdName", PD.PDName))
	}
	if PD.FSType == "" {
		allErrs = append(allErrs, errs.NewFieldRequired("fsType", PD.FSType))
	}
	if PD.Partition < 0 || PD.Partition > 255 {
		allErrs = append(allErrs, errs.NewFieldInvalid("partition", PD.Partition, pdPartitionErrorMsg))
	}
	return allErrs
}

var supportedPortProtocols = util.NewStringSet(string(api.ProtocolTCP), string(api.ProtocolUDP))

func validatePorts(ports []api.Port) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	allNames := util.StringSet{}
	for i, port := range ports {
		pErrs := errs.ValidationErrorList{}
		if len(port.Name) > 0 {
			if len(port.Name) > util.DNS1123LabelMaxLength || !util.IsDNSLabel(port.Name) {
				pErrs = append(pErrs, errs.NewFieldInvalid("name", port.Name, dnsLabelErrorMsg))
			} else if allNames.Has(port.Name) {
				pErrs = append(pErrs, errs.NewFieldDuplicate("name", port.Name))
			} else {
				allNames.Insert(port.Name)
			}
		}
		if port.ContainerPort == 0 {
			pErrs = append(pErrs, errs.NewFieldInvalid("containerPort", port.ContainerPort, portRangeErrorMsg))
		} else if !util.IsValidPortNum(port.ContainerPort) {
			pErrs = append(pErrs, errs.NewFieldInvalid("containerPort", port.ContainerPort, portRangeErrorMsg))
		}
		if port.HostPort != 0 && !util.IsValidPortNum(port.HostPort) {
			pErrs = append(pErrs, errs.NewFieldInvalid("hostPort", port.HostPort, portRangeErrorMsg))
		}
		if len(port.Protocol) == 0 {
			pErrs = append(pErrs, errs.NewFieldRequired("protocol", port.Protocol))
		} else if !supportedPortProtocols.Has(strings.ToUpper(string(port.Protocol))) {
			pErrs = append(pErrs, errs.NewFieldNotSupported("protocol", port.Protocol))
		}
		allErrs = append(allErrs, pErrs.PrefixIndex(i)...)
	}
	return allErrs
}

func validateEnv(vars []api.EnvVar) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	for i, ev := range vars {
		vErrs := errs.ValidationErrorList{}
		if len(ev.Name) == 0 {
			vErrs = append(vErrs, errs.NewFieldRequired("name", ev.Name))
		}
		if !util.IsCIdentifier(ev.Name) {
			vErrs = append(vErrs, errs.NewFieldInvalid("name", ev.Name, cIdentifierErrorMsg))
		}
		allErrs = append(allErrs, vErrs.PrefixIndex(i)...)
	}
	return allErrs
}

func validateVolumeMounts(mounts []api.VolumeMount, volumes util.StringSet) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	for i, mnt := range mounts {
		mErrs := errs.ValidationErrorList{}
		if len(mnt.Name) == 0 {
			mErrs = append(mErrs, errs.NewFieldRequired("name", mnt.Name))
		} else if !volumes.Has(mnt.Name) {
			mErrs = append(mErrs, errs.NewFieldNotFound("name", mnt.Name))
		}
		if len(mnt.MountPath) == 0 {
			mErrs = append(mErrs, errs.NewFieldRequired("mountPath", mnt.MountPath))
		}
		allErrs = append(allErrs, mErrs.PrefixIndex(i)...)
	}
	return allErrs
}

// AccumulateUniquePorts runs an extraction function on each Port of each Container,
// accumulating the results and returning an error if any ports conflict.
func AccumulateUniquePorts(containers []api.Container, accumulator map[int]bool, extract func(*api.Port) int) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	for ci, ctr := range containers {
		cErrs := errs.ValidationErrorList{}
		for pi := range ctr.Ports {
			port := extract(&ctr.Ports[pi])
			if port == 0 {
				continue
			}
			if accumulator[port] {
				cErrs = append(cErrs, errs.NewFieldDuplicate("port", port))
			} else {
				accumulator[port] = true
			}
		}
		allErrs = append(allErrs, cErrs.PrefixIndex(ci)...)
	}
	return allErrs
}

// checkHostPortConflicts checks for colliding Port.HostPort values across
// a slice of containers.
func checkHostPortConflicts(containers []api.Container) errs.ValidationErrorList {
	allPorts := map[int]bool{}
	return AccumulateUniquePorts(containers, allPorts, func(p *api.Port) int { return p.HostPort })
}

func validateExecAction(exec *api.ExecAction) errs.ValidationErrorList {
	allErrors := errs.ValidationErrorList{}
	if len(exec.Command) == 0 {
		allErrors = append(allErrors, errs.NewFieldRequired("command", exec.Command))
	}
	return allErrors
}

func validateHTTPGetAction(http *api.HTTPGetAction) errs.ValidationErrorList {
	allErrors := errs.ValidationErrorList{}
	if len(http.Path) == 0 {
		allErrors = append(allErrors, errs.NewFieldRequired("path", http.Path))
	}
	return allErrors
}

func validateHandler(handler *api.Handler) errs.ValidationErrorList {
	numHandlers := 0
	allErrors := errs.ValidationErrorList{}
	if handler.Exec != nil {
		numHandlers++
		allErrors = append(allErrors, validateExecAction(handler.Exec).Prefix("exec")...)
	}
	if handler.HTTPGet != nil {
		numHandlers++
		allErrors = append(allErrors, validateHTTPGetAction(handler.HTTPGet).Prefix("httpGet")...)
	}
	if numHandlers != 1 {
		allErrors = append(allErrors, errs.NewFieldInvalid("", handler, "exactly 1 handler type is required"))
	}
	return allErrors
}

func validateLifecycle(lifecycle *api.Lifecycle) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if lifecycle.PostStart != nil {
		allErrs = append(allErrs, validateHandler(lifecycle.PostStart).Prefix("postStart")...)
	}
	if lifecycle.PreStop != nil {
		allErrs = append(allErrs, validateHandler(lifecycle.PreStop).Prefix("preStop")...)
	}
	return allErrs
}

func validatePullPolicy(ctr *api.Container) errs.ValidationErrorList {
	allErrors := errs.ValidationErrorList{}

	switch ctr.ImagePullPolicy {
	case api.PullAlways, api.PullIfNotPresent, api.PullNever:
		break
	case "":
		allErrors = append(allErrors, errs.NewFieldRequired("", ctr.ImagePullPolicy))
	default:
		allErrors = append(allErrors, errs.NewFieldNotSupported("", ctr.ImagePullPolicy))
	}

	return allErrors
}

func validateContainers(containers []api.Container, volumes util.StringSet) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	allNames := util.StringSet{}
	for i, ctr := range containers {
		cErrs := errs.ValidationErrorList{}
		capabilities := capabilities.Get()
		if len(ctr.Name) == 0 {
			cErrs = append(cErrs, errs.NewFieldRequired("name", ctr.Name))
		} else if !util.IsDNSLabel(ctr.Name) {
			cErrs = append(cErrs, errs.NewFieldInvalid("name", ctr.Name, dnsLabelErrorMsg))
		} else if allNames.Has(ctr.Name) {
			cErrs = append(cErrs, errs.NewFieldDuplicate("name", ctr.Name))
		} else if ctr.Privileged && !capabilities.AllowPrivileged {
			cErrs = append(cErrs, errs.NewFieldForbidden("privileged", ctr.Privileged))
		} else {
			allNames.Insert(ctr.Name)
		}
		if len(ctr.Image) == 0 {
			cErrs = append(cErrs, errs.NewFieldRequired("image", ctr.Image))
		}
		if ctr.Lifecycle != nil {
			cErrs = append(cErrs, validateLifecycle(ctr.Lifecycle).Prefix("lifecycle")...)
		}
		cErrs = append(cErrs, validatePorts(ctr.Ports).Prefix("ports")...)
		cErrs = append(cErrs, validateEnv(ctr.Env).Prefix("env")...)
		cErrs = append(cErrs, validateVolumeMounts(ctr.VolumeMounts, volumes).Prefix("volumeMounts")...)
		cErrs = append(cErrs, validatePullPolicy(&ctr).Prefix("pullPolicy")...)
		cErrs = append(cErrs, validateResourceRequirements(&ctr).Prefix("resources")...)
		allErrs = append(allErrs, cErrs.PrefixIndex(i)...)
	}
	// Check for colliding ports across all containers.
	// TODO(thockin): This really is dependent on the network config of the host (IP per pod?)
	// and the config of the new manifest.  But we have not specced that out yet, so we'll just
	// make some assumptions for now.  As of now, pods share a network namespace, which means that
	// every Port.HostPort across the whole pod must be unique.
	allErrs = append(allErrs, checkHostPortConflicts(containers)...)

	return allErrs
}

var supportedManifestVersions = util.NewStringSet("v1beta1", "v1beta2")

// ValidateManifest tests that the specified ContainerManifest has valid data.
// This includes checking formatting and uniqueness.  It also canonicalizes the
// structure by setting default values and implementing any backwards-compatibility
// tricks.
// TODO: replaced by ValidatePodSpec
func ValidateManifest(manifest *api.ContainerManifest) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	if len(manifest.Version) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("version", manifest.Version))
	} else if !supportedManifestVersions.Has(strings.ToLower(manifest.Version)) {
		allErrs = append(allErrs, errs.NewFieldNotSupported("version", manifest.Version))
	}
	allVolumes, vErrs := validateVolumes(manifest.Volumes)
	allErrs = append(allErrs, vErrs.Prefix("volumes")...)
	allErrs = append(allErrs, validateContainers(manifest.Containers, allVolumes).Prefix("containers")...)
	allErrs = append(allErrs, validateRestartPolicy(&manifest.RestartPolicy).Prefix("restartPolicy")...)
	allErrs = append(allErrs, validateDNSPolicy(&manifest.DNSPolicy).Prefix("dnsPolicy")...)
	return allErrs
}

func validateRestartPolicy(restartPolicy *api.RestartPolicy) errs.ValidationErrorList {
	numPolicies := 0
	allErrors := errs.ValidationErrorList{}
	if restartPolicy.Always != nil {
		numPolicies++
	}
	if restartPolicy.OnFailure != nil {
		numPolicies++
	}
	if restartPolicy.Never != nil {
		numPolicies++
	}
	if numPolicies != 1 {
		allErrors = append(allErrors, errs.NewFieldInvalid("", restartPolicy, "only 1 policy is allowed"))
	}
	return allErrors
}

func validateDNSPolicy(dnsPolicy *api.DNSPolicy) errs.ValidationErrorList {
	allErrors := errs.ValidationErrorList{}
	switch *dnsPolicy {
	case api.DNSClusterFirst, api.DNSDefault:
		break
	case "":
		allErrors = append(allErrors, errs.NewFieldRequired("", *dnsPolicy))
	default:
		allErrors = append(allErrors, errs.NewFieldNotSupported("", dnsPolicy))
	}
	return allErrors
}

// ValidatePod tests if required fields in the pod are set.
func ValidatePod(pod *api.Pod) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMeta(&pod.ObjectMeta, true, ValidatePodName).Prefix("metadata")...)
	allErrs = append(allErrs, ValidatePodSpec(&pod.Spec).Prefix("spec")...)

	return allErrs
}

// ValidatePodSpec tests that the specified PodSpec has valid data.
// This includes checking formatting and uniqueness.  It also canonicalizes the
// structure by setting default values and implementing any backwards-compatibility
// tricks.
func ValidatePodSpec(spec *api.PodSpec) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	allVolumes, vErrs := validateVolumes(spec.Volumes)
	allErrs = append(allErrs, vErrs.Prefix("volumes")...)
	allErrs = append(allErrs, validateContainers(spec.Containers, allVolumes).Prefix("containers")...)
	allErrs = append(allErrs, validateRestartPolicy(&spec.RestartPolicy).Prefix("restartPolicy")...)
	allErrs = append(allErrs, validateDNSPolicy(&spec.DNSPolicy).Prefix("dnsPolicy")...)
	allErrs = append(allErrs, ValidateLabels(spec.NodeSelector, "nodeSelector")...)
	return allErrs
}

// ValidatePodUpdate tests to see if the update is legal
func ValidatePodUpdate(newPod, oldPod *api.Pod) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	allErrs = append(allErrs, ValidateObjectMetaUpdate(&oldPod.ObjectMeta, &newPod.ObjectMeta).Prefix("metadata")...)

	if len(newPod.Spec.Containers) != len(oldPod.Spec.Containers) {
		allErrs = append(allErrs, errs.NewFieldInvalid("spec.containers", newPod.Spec.Containers, "may not add or remove containers"))
		return allErrs
	}
	pod := *newPod
	// Tricky, we need to copy the container list so that we don't overwrite the update
	var newContainers []api.Container
	for ix, container := range pod.Spec.Containers {
		container.Image = oldPod.Spec.Containers[ix].Image
		newContainers = append(newContainers, container)
	}
	pod.Spec.Containers = newContainers
	if !api.Semantic.DeepEqual(pod.Spec, oldPod.Spec) {
		// TODO: a better error would include all immutable fields explicitly.
		allErrs = append(allErrs, errs.NewFieldInvalid("spec.containers", newPod.Spec.Containers, "some fields are immutable"))
	}

	return allErrs
}

var supportedSessionAffinityType = util.NewStringSet(string(api.AffinityTypeClientIP), string(api.AffinityTypeNone))

// ValidateService tests if required fields in the service are set.
func ValidateService(service *api.Service) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMeta(&service.ObjectMeta, true, ValidateServiceName).Prefix("metadata")...)

	if !util.IsValidPortNum(service.Spec.Port) {
		allErrs = append(allErrs, errs.NewFieldInvalid("spec.port", service.Spec.Port, portRangeErrorMsg))
	}
	if len(service.Spec.Protocol) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("spec.protocol", service.Spec.Protocol))
	} else if !supportedPortProtocols.Has(strings.ToUpper(string(service.Spec.Protocol))) {
		allErrs = append(allErrs, errs.NewFieldNotSupported("spec.protocol", service.Spec.Protocol))
	}

	if service.Spec.Selector != nil {
		allErrs = append(allErrs, ValidateLabels(service.Spec.Selector, "spec.selector")...)
	}

	if service.Spec.SessionAffinity == "" {
		allErrs = append(allErrs, errs.NewFieldRequired("spec.sessionAffinity", service.Spec.SessionAffinity))
	} else if !supportedSessionAffinityType.Has(string(service.Spec.SessionAffinity)) {
		allErrs = append(allErrs, errs.NewFieldNotSupported("spec.sessionAffinity", service.Spec.SessionAffinity))
	}

	return allErrs
}

// ValidateServiceUpdate tests if required fields in the service are set during an update
func ValidateServiceUpdate(oldService, service *api.Service) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMetaUpdate(&oldService.ObjectMeta, &service.ObjectMeta).Prefix("metadata")...)

	// TODO: PortalIP should be a Status field, since the system can set a value != to the user's value
	// PortalIP can only be set, not unset.
	if oldService.Spec.PortalIP != "" && service.Spec.PortalIP != oldService.Spec.PortalIP {
		allErrs = append(allErrs, errs.NewFieldInvalid("spec.portalIP", service.Spec.PortalIP, "field is immutable"))
	}

	return allErrs
}

// ValidateReplicationController tests if required fields in the replication controller are set.
func ValidateReplicationController(controller *api.ReplicationController) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMeta(&controller.ObjectMeta, true, ValidateReplicationControllerName).Prefix("metadata")...)
	allErrs = append(allErrs, ValidateReplicationControllerSpec(&controller.Spec).Prefix("spec")...)

	return allErrs
}

// ValidateReplicationControllerUpdate tests if required fields in the replication controller are set.
func ValidateReplicationControllerUpdate(oldController, controller *api.ReplicationController) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMetaUpdate(&oldController.ObjectMeta, &controller.ObjectMeta).Prefix("metadata")...)
	allErrs = append(allErrs, ValidateReplicationControllerSpec(&controller.Spec).Prefix("spec")...)
	return allErrs
}

// ValidateReplicationControllerSpec tests if required fields in the replication controller spec are set.
func ValidateReplicationControllerSpec(spec *api.ReplicationControllerSpec) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}

	selector := labels.Set(spec.Selector).AsSelector()
	if selector.Empty() {
		allErrs = append(allErrs, errs.NewFieldRequired("selector", spec.Selector))
	}
	if spec.Replicas < 0 {
		allErrs = append(allErrs, errs.NewFieldInvalid("replicas", spec.Replicas, isNegativeErrorMsg))
	}

	if spec.Template == nil {
		allErrs = append(allErrs, errs.NewFieldRequired("template", spec.Template))
	} else {
		labels := labels.Set(spec.Template.Labels)
		if !selector.Matches(labels) {
			allErrs = append(allErrs, errs.NewFieldInvalid("template.labels", spec.Template.Labels, "selector does not match template"))
		}
		allErrs = append(allErrs, ValidatePodTemplateSpec(spec.Template, spec.Replicas).Prefix("template")...)
		// RestartPolicy has already been first-order validated as per ValidatePodTemplateSpec().
		if spec.Template.Spec.RestartPolicy.Always == nil {
			// TODO: should probably be Unsupported
			// TODO: api.RestartPolicy should have a String() method for nicer printing
			allErrs = append(allErrs, errs.NewFieldInvalid("template.restartPolicy", spec.Template.Spec.RestartPolicy, "must be Always"))
		}
	}
	return allErrs
}

// ValidatePodTemplateSpec validates the spec of a pod template
func ValidatePodTemplateSpec(spec *api.PodTemplateSpec, replicas int) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateLabels(spec.Labels, "labels")...)
	allErrs = append(allErrs, ValidateAnnotations(spec.Annotations, "annotations")...)
	allErrs = append(allErrs, ValidatePodSpec(&spec.Spec).Prefix("spec")...)
	if replicas > 1 {
		allErrs = append(allErrs, ValidateReadOnlyPersistentDisks(spec.Spec.Volumes).Prefix("spec.volumes")...)
	}
	return allErrs
}

func ValidateReadOnlyPersistentDisks(volumes []api.Volume) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	for _, vol := range volumes {
		if vol.Source.GCEPersistentDisk != nil {
			if vol.Source.GCEPersistentDisk.ReadOnly == false {
				allErrs = append(allErrs, errs.NewFieldInvalid("GCEPersistentDisk.ReadOnly", false, "ReadOnly must be true for replicated pods > 1, as GCE PD can only be mounted on multiple machines if it is read-only."))
			}
		}
	}
	return allErrs
}

// ValidateBoundPod tests if required fields on a bound pod are set.
// TODO: to be removed.
func ValidateBoundPod(pod *api.BoundPod) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if len(pod.Name) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("name", pod.Name))
	} else {
		if ok, qualifier := nameIsDNSSubdomain(pod.Name, false); !ok {
			allErrs = append(allErrs, errs.NewFieldInvalid("name", pod.Name, qualifier))
		}
	}
	if len(pod.Namespace) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("namespace", pod.Namespace))
	} else if !util.IsDNSSubdomain(pod.Namespace) {
		allErrs = append(allErrs, errs.NewFieldInvalid("namespace", pod.Namespace, dnsSubdomainErrorMsg))
	}
	allErrs = append(allErrs, ValidatePodSpec(&pod.Spec).Prefix("spec")...)
	return allErrs
}

// ValidateMinion tests if required fields in the node are set.
func ValidateMinion(node *api.Node) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMeta(&node.ObjectMeta, false, ValidateNodeName).Prefix("metadata")...)
	return allErrs
}

// ValidateMinionUpdate tests to make sure a minion update can be applied.  Modifies oldMinion.
func ValidateMinionUpdate(oldMinion *api.Node, minion *api.Node) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMetaUpdate(&oldMinion.ObjectMeta, &minion.ObjectMeta).Prefix("metadata")...)

	// TODO: Enable the code once we have better api object.status update model. Currently,
	// anyone can update node status.
	// if !api.Semantic.DeepEqual(minion.Status, api.NodeStatus{}) {
	// 	allErrs = append(allErrs, errs.NewFieldInvalid("status", minion.Status, "status must be empty"))
	// }

	// TODO: move reset function to its own location
	// Ignore metadata changes now that they have been tested
	oldMinion.ObjectMeta = minion.ObjectMeta
	// Allow users to update capacity
	oldMinion.Spec.Capacity = minion.Spec.Capacity
	// Clear status
	oldMinion.Status = minion.Status

	// TODO: Add a 'real' ValidationError type for this error and provide print actual diffs.
	if !api.Semantic.DeepEqual(oldMinion, minion) {
		glog.V(4).Infof("Update failed validation %#v vs %#v", oldMinion, minion)
		allErrs = append(allErrs, fmt.Errorf("update contains more than labels or capacity changes"))
	}

	// TODO: validate Spec.Capacity
	return allErrs
}

// Validate compute resource typename.
// Refer to docs/resources.md for more details.
func validateResourceName(value string, field string) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if !util.IsQualifiedName(value) {
		return append(allErrs, errs.NewFieldInvalid(field, value, "resource typename: "+qualifiedNameErrorMsg))
	}

	if len(strings.Split(value, "/")) == 1 {
		if !api.IsStandardResourceName(value) {
			return append(allErrs, errs.NewFieldInvalid(field, value, "is neither a standard resource type nor is fully qualified"))
		}
	}

	return errs.ValidationErrorList{}
}

// ValidateLimitRange tests if required fields in the LimitRange are set.
func ValidateLimitRange(limitRange *api.LimitRange) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if len(limitRange.Name) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("name", limitRange.Name))
	} else if !util.IsDNSSubdomain(limitRange.Name) {
		allErrs = append(allErrs, errs.NewFieldInvalid("name", limitRange.Name, dnsSubdomainErrorMsg))
	}
	if len(limitRange.Namespace) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("namespace", limitRange.Namespace))
	} else if !util.IsDNSSubdomain(limitRange.Namespace) {
		allErrs = append(allErrs, errs.NewFieldInvalid("namespace", limitRange.Namespace, dnsSubdomainErrorMsg))
	}
	// ensure resource names are properly qualified per docs/resources.md
	for i := range limitRange.Spec.Limits {
		limit := limitRange.Spec.Limits[i]
		for k := range limit.Max {
			allErrs = append(allErrs, validateResourceName(string(k), fmt.Sprintf("spec.limits[%d].max[%s]", i, k))...)
		}
		for k := range limit.Min {
			allErrs = append(allErrs, validateResourceName(string(k), fmt.Sprintf("spec.limits[%d].min[%s]", i, k))...)
		}
	}
	return allErrs
}

func validateBasicResource(quantity resource.Quantity) errs.ValidationErrorList {
	if quantity.Value() < 0 {
		return errs.ValidationErrorList{fmt.Errorf("%v is not a valid resource quantity", quantity.Value())}
	}
	return errs.ValidationErrorList{}
}

// Validates resource requirement spec.
func validateResourceRequirements(container *api.Container) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	for resourceName, quantity := range container.Resources.Limits {
		// Validate resource name.
		errs := validateResourceName(resourceName.String(), fmt.Sprintf("resources.limits[%s]", resourceName))
		if api.IsStandardResourceName(resourceName.String()) {
			errs = append(errs, validateBasicResource(quantity).Prefix(fmt.Sprintf("Resource %s: ", resourceName))...)
		}
		allErrs = append(allErrs, errs...)
	}

	return allErrs
}

// ValidateResourceQuota tests if required fields in the ResourceQuota are set.
func ValidateResourceQuota(resourceQuota *api.ResourceQuota) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	if len(resourceQuota.Name) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("name", resourceQuota.Name))
	} else if !util.IsDNSSubdomain(resourceQuota.Name) {
		allErrs = append(allErrs, errs.NewFieldInvalid("name", resourceQuota.Name, dnsSubdomainErrorMsg))
	}
	if len(resourceQuota.Namespace) == 0 {
		allErrs = append(allErrs, errs.NewFieldRequired("namespace", resourceQuota.Namespace))
	} else if !util.IsDNSSubdomain(resourceQuota.Namespace) {
		allErrs = append(allErrs, errs.NewFieldInvalid("namespace", resourceQuota.Namespace, dnsSubdomainErrorMsg))
	}
	for k := range resourceQuota.Spec.Hard {
		allErrs = append(allErrs, validateResourceName(string(k), string(resourceQuota.TypeMeta.Kind))...)
	}
	for k := range resourceQuota.Status.Hard {
		allErrs = append(allErrs, validateResourceName(string(k), string(resourceQuota.TypeMeta.Kind))...)
	}
	for k := range resourceQuota.Status.Used {
		allErrs = append(allErrs, validateResourceName(string(k), string(resourceQuota.TypeMeta.Kind))...)
	}
	return allErrs
}

// ValidateNamespace tests if required fields are set.
func ValidateNamespace(namespace *api.Namespace) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMeta(&namespace.ObjectMeta, false, ValidateNamespaceName).Prefix("metadata")...)
	return allErrs
}

// ValidateNamespaceUpdate tests to make sure a mamespace update can be applied.  Modifies oldNamespace.
func ValidateNamespaceUpdate(oldNamespace *api.Namespace, namespace *api.Namespace) errs.ValidationErrorList {
	allErrs := errs.ValidationErrorList{}
	allErrs = append(allErrs, ValidateObjectMetaUpdate(&oldNamespace.ObjectMeta, &namespace.ObjectMeta).Prefix("metadata")...)

	// TODO: move reset function to its own location
	// Ignore metadata changes now that they have been tested
	oldNamespace.ObjectMeta = namespace.ObjectMeta

	// TODO: Add a 'real' ValidationError type for this error and provide print actual diffs.
	if !api.Semantic.DeepEqual(oldNamespace, namespace) {
		glog.V(4).Infof("Update failed validation %#v vs %#v", oldNamespace, namespace)
		allErrs = append(allErrs, fmt.Errorf("update contains more than labels or annotation changes"))
	}
	return allErrs
}