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Add support for grpc error details
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When multiple errors are given, use details to encode errors into the
grpc status and decode details back into errors.

Signed-off-by: Derek McGowan <derek@mcg.dev>
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@dmcgowan
dmcgowan committed Jul 2, 2024
1 parent 4c8808b commit 57fa4b4
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Showing 3 changed files with 325 additions and 69 deletions.
284 changes: 219 additions & 65 deletions errgrpc/grpc.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,71 +23,175 @@ package errgrpc

import (
"context"
"errors"
"fmt"
"reflect"
"strconv"
"strings"

spb "google.golang.org/genproto/googleapis/rpc/status"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/protoadapt"
"google.golang.org/protobuf/types/known/anypb"

"github.com/containerd/typeurl/v2"

"github.com/containerd/errdefs"
"github.com/containerd/errdefs/internal/cause"
"github.com/containerd/errdefs/internal/types"
)

// ToGRPC will attempt to map the backend containerd error into a grpc error,
// using the original error message as a description.
// ToGRPC will attempt to map the error into a grpc error, from the error types
// defined in the the errdefs package and attempign to preserve the original
// description. Any type which does not resolve to a defined error type will
// be assigned the unknown error code.
//
// Further information may be extracted from certain errors depending on their
// type.
// type. The grpc error details will be used to attempt to preserve as much of
// the error structures and types as possible.
//
// Errors which can be marshaled using protobuf or typeurl will be considered
// for including as GRPC error details.
// Additionally, use the following interfaces in errors to preserve custom types:
//
// If the error is unmapped, the original error will be returned to be handled
// by the regular grpc error handling stack.
// WrapError(error) error - Used to wrap the previous error
// JoinErrors(...error) error - Used to join all previous errors
// CollapseError() - Used for errors which carry information but
// should not have their error message shown.
func ToGRPC(err error) error {
if err == nil {
return nil
}

if isGRPCError(err) {
if _, ok := status.FromError(err); ok {
// error has already been mapped to grpc
return err
}
st := statusFromError(err)
if st != nil {
if details := errorDetails(err, false); len(details) > 0 {
if ds, _ := st.WithDetails(details...); ds != nil {
st = ds
}
}
err = st.Err()
}
return err
}

switch {
case errdefs.IsInvalidArgument(err):
return status.Error(codes.InvalidArgument, err.Error())
case errdefs.IsNotFound(err):
return status.Error(codes.NotFound, err.Error())
case errdefs.IsAlreadyExists(err):
return status.Error(codes.AlreadyExists, err.Error())
case errdefs.IsFailedPrecondition(err) || errdefs.IsConflict(err) || errdefs.IsNotModified(err):
return status.Error(codes.FailedPrecondition, err.Error())
case errdefs.IsUnavailable(err):
return status.Error(codes.Unavailable, err.Error())
case errdefs.IsNotImplemented(err):
return status.Error(codes.Unimplemented, err.Error())
case errdefs.IsCanceled(err):
return status.Error(codes.Canceled, err.Error())
case errdefs.IsDeadlineExceeded(err):
return status.Error(codes.DeadlineExceeded, err.Error())
case errdefs.IsUnauthorized(err):
return status.Error(codes.Unauthenticated, err.Error())
case errdefs.IsPermissionDenied(err):
return status.Error(codes.PermissionDenied, err.Error())
case errdefs.IsInternal(err):
return status.Error(codes.Internal, err.Error())
case errdefs.IsDataLoss(err):
return status.Error(codes.DataLoss, err.Error())
case errdefs.IsAborted(err):
return status.Error(codes.Aborted, err.Error())
case errdefs.IsOutOfRange(err):
return status.Error(codes.OutOfRange, err.Error())
case errdefs.IsResourceExhausted(err):
return status.Error(codes.ResourceExhausted, err.Error())
case errdefs.IsUnknown(err):
return status.Error(codes.Unknown, err.Error())
func statusFromError(err error) *status.Status {
switch errdefs.Resolve(err) {
case errdefs.ErrInvalidArgument:
return status.New(codes.InvalidArgument, err.Error())
case errdefs.ErrNotFound:
return status.New(codes.NotFound, err.Error())
case errdefs.ErrAlreadyExists:
return status.New(codes.AlreadyExists, err.Error())
case errdefs.ErrPermissionDenied:
return status.New(codes.PermissionDenied, err.Error())
case errdefs.ErrResourceExhausted:
return status.New(codes.ResourceExhausted, err.Error())
case errdefs.ErrFailedPrecondition, errdefs.ErrConflict, errdefs.ErrNotModified:
return status.New(codes.FailedPrecondition, err.Error())
case errdefs.ErrAborted:
return status.New(codes.Aborted, err.Error())
case errdefs.ErrOutOfRange:
return status.New(codes.OutOfRange, err.Error())
case errdefs.ErrNotImplemented:
return status.New(codes.Unimplemented, err.Error())
case errdefs.ErrInternal:
return status.New(codes.Internal, err.Error())
case errdefs.ErrUnavailable:
return status.New(codes.Unavailable, err.Error())
case errdefs.ErrDataLoss:
return status.New(codes.DataLoss, err.Error())
case errdefs.ErrUnauthenticated:
return status.New(codes.Unauthenticated, err.Error())
case context.DeadlineExceeded:
return status.New(codes.DeadlineExceeded, err.Error())
case context.Canceled:
return status.New(codes.Canceled, err.Error())
case errdefs.ErrUnknown:
return status.New(codes.Unknown, err.Error())
}
return nil
}

return err
// errorDetails returns an array of errors which make up the provided error.
// If firstIncluded is true, then all encodable errors will be used, otherwise
// the first error in an error list will be not be used, to account for the
// the base status error which details are added to via wrap or join.
//
// The errors are ordered in way that they can be applied in order by either
// wrapping or joining the errors to recreate an error with the same structure
// when `WrapError` and `JoinErrors` interfaces are used.
//
// The intent is that when re-applying the errors to create a single error, the
// results of calls to `Error()`, `errors.Is`, `errors.As`, and "%+v" formatting
// is the same as the original error.
func errorDetails(err error, firstIncluded bool) []protoadapt.MessageV1 {
switch uerr := err.(type) {
case interface{ Unwrap() error }:
details := errorDetails(uerr.Unwrap(), firstIncluded)

// If the type is able to wrap, then include if proto
if _, ok := err.(interface{ WrapError(error) error }); ok {
// Get proto message
if protoErr := toProtoMessage(err); protoErr != nil {
details = append(details, protoErr)
}
}

return details
case interface{ Unwrap() []error }:
var details []protoadapt.MessageV1
for i, e := range uerr.Unwrap() {
details = append(details, errorDetails(e, firstIncluded || i > 0)...)
}

if _, ok := err.(interface{ JoinErrors(...error) error }); ok {
// Get proto message
if protoErr := toProtoMessage(err); protoErr != nil {
details = append(details, protoErr)
}
}
return details
}

if firstIncluded {
if protoErr := toProtoMessage(err); protoErr != nil {
return []protoadapt.MessageV1{protoErr}
}
if gs, ok := status.FromError(ToGRPC(err)); ok {
return []protoadapt.MessageV1{gs.Proto()}
}
// TODO: Else include unknown extra error type?
}

return nil
}

func toProtoMessage(err error) protoadapt.MessageV1 {
// Do not double encode proto messages, otherwise use Any
if pm, ok := err.(protoadapt.MessageV1); ok {
return pm
}
if pm, ok := err.(proto.Message); ok {
return protoadapt.MessageV1Of(pm)
}

if reflect.TypeOf(err).Kind() == reflect.Ptr {
a, aerr := typeurl.MarshalAny(err)
if aerr == nil {
return &anypb.Any{
TypeUrl: a.GetTypeUrl(),
Value: a.GetValue(),
}
}
}
return nil
}

// ToGRPCf maps the error to grpc error codes, assembling the formatting string
Expand All @@ -98,17 +202,33 @@ func ToGRPCf(err error, format string, args ...interface{}) error {
return ToGRPC(fmt.Errorf("%s: %w", fmt.Sprintf(format, args...), err))
}

// ToNative returns the underlying error from a grpc service based on the grpc error code
// ToNative returns the underlying error from a grpc service based on the grpc
// error code. The grpc details are used to add wrap the error in more context
// or support multiple errors.
func ToNative(err error) error {
if err == nil {
return nil
}

desc := errDesc(err)
s, isGRPC := status.FromError(err)

var (
desc string
code codes.Code
)

if isGRPC {
desc = s.Message()
code = s.Code()

} else {
desc = err.Error()
code = codes.Unknown
}

var cls error // divide these into error classes, becomes the cause

switch code(err) {
switch code {
case codes.InvalidArgument:
cls = errdefs.ErrInvalidArgument
case codes.AlreadyExists:
Expand All @@ -118,6 +238,10 @@ func ToNative(err error) error {
case codes.Unavailable:
cls = errdefs.ErrUnavailable
case codes.FailedPrecondition:
// TODO: Has suffix is not sufficient for conflict and not modified
// Message should start with ": " or be at beginning of a line
// Message should end with ": " or be at the end of a line
// Compile a regex
if desc == errdefs.ErrConflict.Error() || strings.HasSuffix(desc, ": "+errdefs.ErrConflict.Error()) {
cls = errdefs.ErrConflict
} else if desc == errdefs.ErrNotModified.Error() || strings.HasSuffix(desc, ": "+errdefs.ErrNotModified.Error()) {
Expand Down Expand Up @@ -147,7 +271,7 @@ func ToNative(err error) error {
cls = errdefs.ErrResourceExhausted
default:
if idx := strings.LastIndex(desc, cause.UnexpectedStatusPrefix); idx > 0 {
if status, err := strconv.Atoi(desc[idx+len(cause.UnexpectedStatusPrefix):]); err == nil && status >= 200 && status < 600 {
if status, uerr := strconv.Atoi(desc[idx+len(cause.UnexpectedStatusPrefix):]); uerr == nil && status >= 200 && status < 600 {
cls = cause.ErrUnexpectedStatus{Status: status}
}
}
Expand All @@ -157,10 +281,59 @@ func ToNative(err error) error {
}

msg := rebaseMessage(cls, desc)
if msg != "" {
if msg == "" {
err = cls
} else if msg != desc {
err = fmt.Errorf("%s: %w", msg, cls)
} else if wm, ok := cls.(interface{ WithMessage(string) error }); ok {
err = wm.WithMessage(msg)
} else {
err = cls
err = fmt.Errorf("%s: %w", msg, cls)
}

if isGRPC {
errs := []error{err}
for _, a := range s.Details() {
var derr error

// First decode error if needed
if s, ok := a.(*spb.Status); ok {
derr = ToNative(status.ErrorProto(s))
} else if e, ok := a.(error); ok {
derr = e
} else if dany, ok := a.(typeurl.Any); ok {
i, uerr := typeurl.UnmarshalAny(dany)
if uerr == nil {
if e, ok = i.(error); ok {
derr = e
} else {
derr = fmt.Errorf("non-error unmarshalled detail: %v", i)
}
} else {
derr = fmt.Errorf("error of type %q with failure to unmarshal: %v", dany.GetTypeUrl(), uerr)
}
} else {
derr = fmt.Errorf("non-error detail: %v", a)
}

switch werr := derr.(type) {
case interface{ WrapError(error) error }:
errs[len(errs)-1] = werr.WrapError(errs[len(errs)-1])
case interface{ JoinErrors(...error) error }:
// TODO: Consider whether this should support joining a subset
errs[0] = werr.JoinErrors(errs...)
case interface{ CollapseError() }:
errs[len(errs)-1] = types.CollapsedError(errs[len(errs)-1], derr)
default:
errs = append(errs, derr)
}

}
if len(errs) > 1 {
err = errors.Join(errs...)
} else {
err = errs[0]
}
}

return err
Expand All @@ -179,22 +352,3 @@ func rebaseMessage(cls error, desc string) string {

return strings.TrimSuffix(desc, ": "+clss)
}

func isGRPCError(err error) bool {
_, ok := status.FromError(err)
return ok
}

func code(err error) codes.Code {
if s, ok := status.FromError(err); ok {
return s.Code()
}
return codes.Unknown
}

func errDesc(err error) string {
if s, ok := status.FromError(err); ok {
return s.Message()
}
return err.Error()
}
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