open-consul/agent/grpc-external/services/resource/write.go
Semir Patel 2409c32e20
De-scope tenenacy requirements to OSS only for now. (#17087)
Partition and namespace must be "default"
Peername must be "local"
2023-04-24 08:14:51 -05:00

248 lines
7.8 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package resource
import (
"context"
"errors"
"strings"
"time"
"github.com/oklog/ulid/v2"
"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) {
if err := validateWriteRequest(req); err != nil {
return nil, err
}
reg, err := s.resolveType(req.Resource.Id.Type)
if err != nil {
return nil, err
}
authz, err := s.getAuthorizer(tokenFromContext(ctx))
if err != nil {
return nil, err
}
// check acls
err = reg.ACLs.Write(authz, req.Resource.Id)
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 the user sent the correct type of data.
if !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.Validate(req.Resource); err != nil {
return nil, status.Error(codes.InvalidArgument, err.Error())
}
if err = reg.Mutate(req.Resource); err != nil {
return nil, status.Errorf(codes.Internal, "failed mutate hook: %v", err.Error())
}
// 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.
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
}
// TODO(spatel): Revisit owner<->resource tenancy rules post-1.16
// Update path.
case err == nil:
// 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.
if input.Version == "" {
input.Version = existing.Version
}
// 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
}
// Owner can only be set on creation. Enforce immutability.
if !proto.Equal(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.EqualStatus(input.Status, existing.Status) {
return errUseWriteStatus
}
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 validateWriteRequest(req *pbresource.WriteRequest) error {
var field string
switch {
case req.Resource == nil:
field = "resource"
case req.Resource.Id == nil:
field = "resource.id"
case req.Resource.Data == nil:
field = "resource.data"
}
if field != "" {
return status.Errorf(codes.InvalidArgument, "%s is required", field)
}
if err := validateId(req.Resource.Id, "resource.id"); err != nil {
return err
}
if req.Resource.Owner != nil {
if err := validateId(req.Resource.Owner, "resource.owner"); err != nil {
return err
}
}
return nil
}