consul/agent/grpc-external/services/resource/write.go

473 lines
17 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1
package resource
import (
"context"
"errors"
"strings"
"time"
"github.com/oklog/ulid/v2"
"golang.org/x/exp/maps"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
"google.golang.org/protobuf/proto"
"github.com/hashicorp/consul/acl"
"github.com/hashicorp/consul/internal/resource"
"github.com/hashicorp/consul/internal/storage"
"github.com/hashicorp/consul/lib/retry"
"github.com/hashicorp/consul/proto-public/pbresource"
)
// errUseWriteStatus is returned when the user attempts to modify the resource
// status using the Write endpoint.
//
// We only allow modifications to the status using the WriteStatus endpoint
// because:
//
// - Setting statuses should only be done by controllers and requires different
// permissions.
//
// - Status-only updates shouldn't increment the resource generation.
//
// While we could accomplish both in the Write handler, there's seldom need to
// update the resource body and status at the same time, so it makes more sense
// to keep them separate.
var errUseWriteStatus = status.Error(codes.InvalidArgument, "resource.status can only be set using the WriteStatus endpoint")
func (s *Server) Write(ctx context.Context, req *pbresource.WriteRequest) (*pbresource.WriteResponse, error) {
reg, err := s.ensureWriteRequestValid(req)
if err != nil {
return nil, err
}
v1EntMeta := v2TenancyToV1EntMeta(req.Resource.Id.Tenancy)
authz, authzContext, err := s.getAuthorizer(tokenFromContext(ctx), v1EntMeta)
if err != nil {
return nil, err
}
v1EntMetaToV2Tenancy(reg, v1EntMeta, req.Resource.Id.Tenancy)
// Check the user sent the correct type of data.
if req.Resource.Data != nil && !req.Resource.Data.MessageIs(reg.Proto) {
got := strings.TrimPrefix(req.Resource.Data.TypeUrl, "type.googleapis.com/")
return nil, status.Errorf(
codes.InvalidArgument,
"resource.data is of wrong type (expected=%q, got=%q)",
reg.Proto.ProtoReflect().Descriptor().FullName(),
got,
)
}
if err = reg.Mutate(req.Resource); err != nil {
return nil, status.Errorf(codes.Internal, "failed mutate hook: %v", err.Error())
}
if err = reg.Validate(req.Resource); err != nil {
return nil, status.Error(codes.InvalidArgument, err.Error())
}
// ACL check comes before tenancy existence checks to not leak tenancy "existence".
err = reg.ACLs.Write(authz, authzContext, req.Resource)
switch {
case acl.IsErrPermissionDenied(err):
return nil, status.Error(codes.PermissionDenied, err.Error())
case err != nil:
return nil, status.Errorf(codes.Internal, "failed write acl: %v", err)
}
// Check tenancy exists for the V2 resource
if err = tenancyExists(reg, s.TenancyBridge, req.Resource.Id.Tenancy, codes.InvalidArgument); err != nil {
return nil, err
}
// This is used later in the "create" and "update" paths to block non-delete related writes
// when a tenancy unit has been marked for deletion.
tenancyMarkedForDeletion, err := isTenancyMarkedForDeletion(reg, s.TenancyBridge, req.Resource.Id.Tenancy)
if err != nil {
return nil, status.Errorf(codes.Internal, "failed tenancy marked for deletion check: %v", err)
}
// At the storage backend layer, all writes are CAS operations.
//
// This makes it possible to *safely* do things like keeping the Uid stable
// across writes, carrying statuses over, and passing the current version of
// the resource to hooks, without restricting ourselves to only using the more
// feature-rich storage systems that support "patch" updates etc. natively.
//
// Although CAS semantics are useful for machine users like controllers, human
// users generally don't need them. If the user is performing a non-CAS write,
// we read the current version, and automatically retry if the CAS write fails.
var result *pbresource.Resource
err = s.retryCAS(ctx, req.Resource.Version, func() error {
input := clone(req.Resource)
// We read with EventualConsistency here because:
//
// - In the common case, individual resources are written infrequently, and
// when using the Raft backend followers are generally within a few hundred
// milliseconds of the leader, so the first read will probably return the
// current version.
//
// - StrongConsistency is expensive. In the Raft backend, it involves a round
// of heartbeats to verify cluster leadership (in addition to the write's
// log replication).
//
// - CAS failures will be retried by retryCAS anyway. So the read-modify-write
// cycle should eventually succeed.
var mismatchError storage.GroupVersionMismatchError
existing, err := s.Backend.Read(ctx, storage.EventualConsistency, input.Id)
switch {
// Create path.
case errors.Is(err, storage.ErrNotFound):
input.Id.Uid = ulid.Make().String()
// Prevent setting statuses in this endpoint.
if len(input.Status) != 0 {
return errUseWriteStatus
}
// Reject creation in tenancy unit marked for deletion.
if tenancyMarkedForDeletion {
return status.Errorf(codes.InvalidArgument, "tenancy marked for deletion: %v", input.Id.Tenancy.String())
}
// Reject attempts to create a resource with a deletionTimestamp.
if resource.IsMarkedForDeletion(input) {
return status.Errorf(codes.InvalidArgument, "resource.metadata.%s can't be set on resource creation", resource.DeletionTimestampKey)
}
// Generally, we expect resources with owners to be created by controllers,
// and they should provide the Uid. In cases where no Uid is given (e.g. the
// owner is specified in the resource HCL) we'll look up whatever the current
// Uid is and use that.
//
// An important note on consistency:
//
// We read the owner with StrongConsistency here to reduce the likelihood of
// creating a resource pointing to the wrong "incarnation" of the owner in
// cases where the owner is deleted and re-created in quick succession.
//
// That said, there is still a chance that the owner has been deleted by the
// time we write this resource. This is not a relational database and we do
// not support ACID transactions or real foreign key constraints.
if input.Owner != nil && input.Owner.Uid == "" {
owner, err := s.Backend.Read(ctx, storage.StrongConsistency, input.Owner)
switch {
case errors.Is(err, storage.ErrNotFound):
return status.Error(codes.InvalidArgument, "resource.owner does not exist")
case err != nil:
return status.Errorf(codes.Internal, "failed to resolve owner: %v", err)
}
input.Owner = owner.Id
}
// TODO(spatel): Revisit owner<->resource tenancy rules post-1.16
// Update path.
case err == nil || errors.As(err, &mismatchError):
// Allow writes that update GroupVersion.
if mismatchError.Stored != nil {
existing = mismatchError.Stored
}
// Use the stored ID because it includes the Uid.
//
// Generally, users won't provide the Uid but controllers will, because
// controllers need to operate on a specific "incarnation" of a resource
// as opposed to an older/newer resource with the same name, whereas users
// just want to update the current resource.
input.Id = existing.Id
// User is doing a non-CAS write, use the current version and preserve
// deferred deletion metadata if not present.
if input.Version == "" {
input.Version = existing.Version
preserveDeferredDeletionMetadata(input, existing)
}
// Check the stored version matches the user-given version.
//
// Although CAS operations are implemented "for real" at the storage backend
// layer, we must check the version here too to prevent a scenario where:
//
// - Current resource version is `v2`
// - User passes version `v2`
// - Read returns stale version `v1`
// - We carry `v1`'s statuses over (effectively overwriting `v2`'s statuses)
// - CAS operation succeeds anyway because user-given version is current
if input.Version != existing.Version {
return storage.ErrCASFailure
}
// Fill in an empty Owner UID with the existing owner's UID. If other parts
// of the owner ID like the type or name have changed then the subsequent
// EqualID call will still error as you are not allowed to change the owner.
// This is a small UX nicety to repeatedly "apply" a resource that should
// have an owner without having to care about the current owners incarnation.
if input.Owner != nil && existing.Owner != nil && input.Owner.Uid == "" {
input.Owner.Uid = existing.Owner.Uid
}
// Owner can only be set on creation. Enforce immutability.
if !resource.EqualID(input.Owner, existing.Owner) {
return status.Errorf(codes.InvalidArgument, "owner cannot be changed")
}
// Carry over status and prevent updates
if input.Status == nil {
input.Status = existing.Status
} else if !resource.EqualStatusMap(input.Status, existing.Status) {
return errUseWriteStatus
}
// If the write is related to a deferred deletion (marking for deletion or removal
// of finalizers), make sure nothing else is changed.
if err := vetIfDeleteRelated(input, existing, tenancyMarkedForDeletion); err != nil {
return err
}
// Otherwise, let the write continue
default:
return err
}
input.Generation = ulid.Make().String()
result, err = s.Backend.WriteCAS(ctx, input)
return err
})
switch {
case errors.Is(err, storage.ErrCASFailure):
return nil, status.Error(codes.Aborted, err.Error())
case errors.Is(err, storage.ErrWrongUid):
return nil, status.Error(codes.FailedPrecondition, err.Error())
case isGRPCStatusError(err):
return nil, err
case err != nil:
return nil, status.Errorf(codes.Internal, "failed to write resource: %v", err.Error())
}
return &pbresource.WriteResponse{Resource: result}, nil
}
// retryCAS retries the given operation with exponential backoff if the user
// didn't provide a version. This is intended to hide failures when the user
// isn't intentionally performing a CAS operation (all writes are, by design,
// CAS operations at the storage backend layer).
func (s *Server) retryCAS(ctx context.Context, vsn string, cas func() error) error {
if vsn != "" {
return cas()
}
const maxAttempts = 5
// These parameters are fairly arbitrary, so if you find better ones then go
// ahead and swap them out! In general, we want to wait long enough to smooth
// over small amounts of storage replication lag, but not so long that we make
// matters worse by holding onto load.
backoff := &retry.Waiter{
MinWait: 50 * time.Millisecond,
MaxWait: 1 * time.Second,
Jitter: retry.NewJitter(50),
Factor: 75 * time.Millisecond,
}
var err error
for i := 1; i <= maxAttempts; i++ {
if err = cas(); !errors.Is(err, storage.ErrCASFailure) {
break
}
if backoff.Wait(ctx) != nil {
break
}
s.Logger.Trace("retrying failed CAS operation", "failure_count", i)
}
return err
}
func (s *Server) ensureWriteRequestValid(req *pbresource.WriteRequest) (*resource.Registration, error) {
var field string
switch {
case req.Resource == nil:
field = "resource"
case req.Resource.Id == nil:
field = "resource.id"
}
if field != "" {
return nil, status.Errorf(codes.InvalidArgument, "%s is required", field)
}
if err := validateId(req.Resource.Id, "resource.id"); err != nil {
return nil, err
}
if req.Resource.Owner != nil {
if err := validateId(req.Resource.Owner, "resource.owner"); err != nil {
return nil, err
}
}
// Check type exists.
reg, err := s.resolveType(req.Resource.Id.Type)
if err != nil {
return nil, err
}
if err = checkV2Tenancy(s.UseV2Tenancy, req.Resource.Id.Type); err != nil {
return nil, err
}
// Check scope
if reg.Scope == resource.ScopePartition && req.Resource.Id.Tenancy.Namespace != "" {
return nil, status.Errorf(
codes.InvalidArgument,
"partition scoped resource %s cannot have a namespace. got: %s",
resource.ToGVK(req.Resource.Id.Type),
req.Resource.Id.Tenancy.Namespace,
)
}
return reg, nil
}
func ensureMetadataSameExceptFor(input *pbresource.Resource, existing *pbresource.Resource, ignoreKey string) error {
// Work on copies since we're mutating them
inputCopy := maps.Clone(input.Metadata)
existingCopy := maps.Clone(existing.Metadata)
delete(inputCopy, ignoreKey)
delete(existingCopy, ignoreKey)
if !maps.Equal(inputCopy, existingCopy) {
return status.Error(codes.InvalidArgument, "cannot modify metadata")
}
return nil
}
func ensureDataUnchanged(input *pbresource.Resource, existing *pbresource.Resource) error {
// Check data last since this could potentially be the most expensive comparison.
if !proto.Equal(input.Data, existing.Data) {
return status.Error(codes.InvalidArgument, "cannot modify data")
}
return nil
}
// EnsureFinalizerRemoved ensures at least one finalizer was removed.
// TODO: only public for test to access
func EnsureFinalizerRemoved(input *pbresource.Resource, existing *pbresource.Resource) error {
inputFinalizers := resource.GetFinalizers(input)
existingFinalizers := resource.GetFinalizers(existing)
if !inputFinalizers.IsProperSubset(existingFinalizers) {
return status.Error(codes.InvalidArgument, "expected at least one finalizer to be removed")
}
return nil
}
func vetIfDeleteRelated(input, existing *pbresource.Resource, tenancyMarkedForDeletion bool) error {
// Keep track of whether this write is a normal write or a write that is related
// to deferred resource deletion involving setting the deletionTimestamp or the
// removal of finalizers.
deleteRelated := false
existingMarked := resource.IsMarkedForDeletion(existing)
inputMarked := resource.IsMarkedForDeletion(input)
// Block removal of deletion timestamp
if !inputMarked && existingMarked {
return status.Errorf(codes.InvalidArgument, "cannot remove %s", resource.DeletionTimestampKey)
}
// Block modification of existing deletion timestamp
if existing.Metadata[resource.DeletionTimestampKey] != "" && (existing.Metadata[resource.DeletionTimestampKey] != input.Metadata[resource.DeletionTimestampKey]) {
return status.Errorf(codes.InvalidArgument, "cannot modify %s", resource.DeletionTimestampKey)
}
// Block writes that do more than just adding a deletion timestamp
if inputMarked && !existingMarked {
deleteRelated = deleteRelated || true
// Verify rest of resource is unchanged
if err := ensureMetadataSameExceptFor(input, existing, resource.DeletionTimestampKey); err != nil {
return err
}
if err := ensureDataUnchanged(input, existing); err != nil {
return err
}
}
// Block no-op writes writes to resource that already has a deletion timestamp. The
// only valid writes should be removal of finalizers.
if inputMarked && existingMarked {
deleteRelated = deleteRelated || true
// Check if a no-op
errMetadataSame := ensureMetadataSameExceptFor(input, existing, resource.DeletionTimestampKey)
errDataUnchanged := ensureDataUnchanged(input, existing)
if errMetadataSame == nil && errDataUnchanged == nil {
return status.Error(codes.InvalidArgument, "cannot no-op write resource marked for deletion")
}
}
// Block writes that do more than removing finalizers if previously marked for deletion.
if inputMarked && existingMarked && resource.HasFinalizers(existing) {
deleteRelated = deleteRelated || true
if err := ensureMetadataSameExceptFor(input, existing, resource.FinalizerKey); err != nil {
return err
}
if err := ensureDataUnchanged(input, existing); err != nil {
return err
}
if err := EnsureFinalizerRemoved(input, existing); err != nil {
return err
}
}
// Classify writes that just remove finalizer as deleteRelated regardless of deletion state.
if err := EnsureFinalizerRemoved(input, existing); err == nil {
if err := ensureDataUnchanged(input, existing); err == nil {
deleteRelated = deleteRelated || true
}
}
// Lastly, block writes when the resource's tenancy unit has been marked for deletion and
// the write is not related a valid delete scenario.
if tenancyMarkedForDeletion && !deleteRelated {
return status.Errorf(codes.InvalidArgument, "cannot write resource when tenancy marked for deletion: %s", existing.Id.Tenancy)
}
return nil
}
// preserveDeferredDeletionMetadata only applies to user writes (Version == "") which is a precondition.
func preserveDeferredDeletionMetadata(input, existing *pbresource.Resource) {
// preserve existing deletionTimestamp if not provided in input
if !resource.IsMarkedForDeletion(input) && resource.IsMarkedForDeletion(existing) {
if input.Metadata == nil {
input.Metadata = make(map[string]string)
}
input.Metadata[resource.DeletionTimestampKey] = existing.Metadata[resource.DeletionTimestampKey]
}
// Only preserve finalizers if the is key absent from input and present in existing.
// If the key is present in input, the user clearly wants to remove finalizers!
inputHasKey := false
if input.Metadata != nil {
_, inputHasKey = input.Metadata[resource.FinalizerKey]
}
existingHasKey := false
if existing.Metadata != nil {
_, existingHasKey = existing.Metadata[resource.FinalizerKey]
}
if !inputHasKey && existingHasKey {
if input.Metadata == nil {
input.Metadata = make(map[string]string)
}
input.Metadata[resource.FinalizerKey] = existing.Metadata[resource.FinalizerKey]
}
}