2409c32e20
Partition and namespace must be "default" Peername must be "local"
248 lines
7.8 KiB
Go
248 lines
7.8 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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package resource
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import (
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"context"
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"errors"
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"strings"
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"time"
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"github.com/oklog/ulid/v2"
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"google.golang.org/grpc/codes"
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"google.golang.org/grpc/status"
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"google.golang.org/protobuf/proto"
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"github.com/hashicorp/consul/acl"
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"github.com/hashicorp/consul/internal/resource"
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"github.com/hashicorp/consul/internal/storage"
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"github.com/hashicorp/consul/lib/retry"
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"github.com/hashicorp/consul/proto-public/pbresource"
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)
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// errUseWriteStatus is returned when the user attempts to modify the resource
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// status using the Write endpoint.
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//
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// We only allow modifications to the status using the WriteStatus endpoint
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// because:
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//
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// - Setting statuses should only be done by controllers and requires different
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// permissions.
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//
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// - Status-only updates shouldn't increment the resource generation.
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//
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// While we could accomplish both in the Write handler, there's seldom need to
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// update the resource body and status at the same time, so it makes more sense
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// to keep them separate.
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var errUseWriteStatus = status.Error(codes.InvalidArgument, "resource.status can only be set using the WriteStatus endpoint")
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func (s *Server) Write(ctx context.Context, req *pbresource.WriteRequest) (*pbresource.WriteResponse, error) {
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if err := validateWriteRequest(req); err != nil {
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return nil, err
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}
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reg, err := s.resolveType(req.Resource.Id.Type)
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if err != nil {
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return nil, err
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}
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authz, err := s.getAuthorizer(tokenFromContext(ctx))
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if err != nil {
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return nil, err
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}
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// check acls
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err = reg.ACLs.Write(authz, req.Resource.Id)
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switch {
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case acl.IsErrPermissionDenied(err):
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return nil, status.Error(codes.PermissionDenied, err.Error())
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case err != nil:
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return nil, status.Errorf(codes.Internal, "failed write acl: %v", err)
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}
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// Check the user sent the correct type of data.
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if !req.Resource.Data.MessageIs(reg.Proto) {
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got := strings.TrimPrefix(req.Resource.Data.TypeUrl, "type.googleapis.com/")
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return nil, status.Errorf(
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codes.InvalidArgument,
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"resource.data is of wrong type (expected=%q, got=%q)",
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reg.Proto.ProtoReflect().Descriptor().FullName(),
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got,
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)
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}
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if err = reg.Validate(req.Resource); err != nil {
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return nil, status.Error(codes.InvalidArgument, err.Error())
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}
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if err = reg.Mutate(req.Resource); err != nil {
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return nil, status.Errorf(codes.Internal, "failed mutate hook: %v", err.Error())
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}
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// At the storage backend layer, all writes are CAS operations.
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//
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// This makes it possible to *safely* do things like keeping the Uid stable
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// across writes, carrying statuses over, and passing the current version of
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// the resource to hooks, without restricting ourselves to only using the more
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// feature-rich storage systems that support "patch" updates etc. natively.
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//
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// Although CAS semantics are useful for machine users like controllers, human
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// users generally don't need them. If the user is performing a non-CAS write,
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// we read the current version, and automatically retry if the CAS write fails.
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var result *pbresource.Resource
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err = s.retryCAS(ctx, req.Resource.Version, func() error {
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input := clone(req.Resource)
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// We read with EventualConsistency here because:
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//
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// - In the common case, individual resources are written infrequently, and
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// when using the Raft backend followers are generally within a few hundred
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// milliseconds of the leader, so the first read will probably return the
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// current version.
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//
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// - StrongConsistency is expensive. In the Raft backend, it involves a round
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// of heartbeats to verify cluster leadership (in addition to the write's
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// log replication).
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//
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// - CAS failures will be retried by retryCAS anyway. So the read-modify-write
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// cycle should eventually succeed.
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existing, err := s.Backend.Read(ctx, storage.EventualConsistency, input.Id)
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switch {
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// Create path.
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case errors.Is(err, storage.ErrNotFound):
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input.Id.Uid = ulid.Make().String()
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// Prevent setting statuses in this endpoint.
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if len(input.Status) != 0 {
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return errUseWriteStatus
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}
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// TODO(spatel): Revisit owner<->resource tenancy rules post-1.16
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// Update path.
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case err == nil:
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// Use the stored ID because it includes the Uid.
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//
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// Generally, users won't provide the Uid but controllers will, because
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// controllers need to operate on a specific "incarnation" of a resource
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// as opposed to an older/newer resource with the same name, whereas users
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// just want to update the current resource.
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input.Id = existing.Id
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// User is doing a non-CAS write, use the current version.
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if input.Version == "" {
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input.Version = existing.Version
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}
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// Check the stored version matches the user-given version.
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//
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// Although CAS operations are implemented "for real" at the storage backend
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// layer, we must check the version here too to prevent a scenario where:
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//
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// - Current resource version is `v2`
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// - User passes version `v2`
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// - Read returns stale version `v1`
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// - We carry `v1`'s statuses over (effectively overwriting `v2`'s statuses)
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// - CAS operation succeeds anyway because user-given version is current
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if input.Version != existing.Version {
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return storage.ErrCASFailure
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}
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// Owner can only be set on creation. Enforce immutability.
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if !proto.Equal(input.Owner, existing.Owner) {
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return status.Errorf(codes.InvalidArgument, "owner cannot be changed")
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}
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// Carry over status and prevent updates
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if input.Status == nil {
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input.Status = existing.Status
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} else if !resource.EqualStatus(input.Status, existing.Status) {
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return errUseWriteStatus
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}
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default:
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return err
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}
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input.Generation = ulid.Make().String()
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result, err = s.Backend.WriteCAS(ctx, input)
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return err
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})
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switch {
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case errors.Is(err, storage.ErrCASFailure):
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return nil, status.Error(codes.Aborted, err.Error())
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case errors.Is(err, storage.ErrWrongUid):
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return nil, status.Error(codes.FailedPrecondition, err.Error())
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case isGRPCStatusError(err):
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return nil, err
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case err != nil:
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return nil, status.Errorf(codes.Internal, "failed to write resource: %v", err.Error())
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}
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return &pbresource.WriteResponse{Resource: result}, nil
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}
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// retryCAS retries the given operation with exponential backoff if the user
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// didn't provide a version. This is intended to hide failures when the user
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// isn't intentionally performing a CAS operation (all writes are, by design,
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// CAS operations at the storage backend layer).
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func (s *Server) retryCAS(ctx context.Context, vsn string, cas func() error) error {
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if vsn != "" {
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return cas()
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}
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const maxAttempts = 5
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// These parameters are fairly arbitrary, so if you find better ones then go
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// ahead and swap them out! In general, we want to wait long enough to smooth
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// over small amounts of storage replication lag, but not so long that we make
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// matters worse by holding onto load.
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backoff := &retry.Waiter{
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MinWait: 50 * time.Millisecond,
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MaxWait: 1 * time.Second,
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Jitter: retry.NewJitter(50),
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Factor: 75 * time.Millisecond,
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}
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var err error
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for i := 1; i <= maxAttempts; i++ {
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if err = cas(); !errors.Is(err, storage.ErrCASFailure) {
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break
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}
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if backoff.Wait(ctx) != nil {
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break
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}
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s.Logger.Trace("retrying failed CAS operation", "failure_count", i)
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}
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return err
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}
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func validateWriteRequest(req *pbresource.WriteRequest) error {
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var field string
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switch {
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case req.Resource == nil:
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field = "resource"
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case req.Resource.Id == nil:
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field = "resource.id"
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case req.Resource.Data == nil:
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field = "resource.data"
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}
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if field != "" {
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return status.Errorf(codes.InvalidArgument, "%s is required", field)
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}
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if err := validateId(req.Resource.Id, "resource.id"); err != nil {
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return err
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}
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if req.Resource.Owner != nil {
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if err := validateId(req.Resource.Owner, "resource.owner"); err != nil {
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return err
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}
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}
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return nil
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}
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