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errdefs: centralize error handling

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Now that we have most of the services required for use with containerd,
it was found that common patterns were used throughout services. By
defining a central `errdefs` package, we ensure that services will map
errors to and from grpc consistently and cleanly. One can decorate an
error with as much context as necessary, using `pkg/errors` and still
have the error mapped correctly via grpc.

We make a few sacrifices. At this point, the common errors we use across
the repository all map directly to grpc error codes. While this seems
positively crazy, it actually works out quite well. The error conditions
that were specific weren't super necessary and the ones that were
necessary now simply have better context information. We lose the
ability to add new codes, but this constraint may not be a bad thing.

Effectively, as long as one uses the errors defined in `errdefs`, the
error class will be mapped correctly across the grpc boundary and
everything will be good. If you don't use those definitions, the error
maps to "unknown" and the error message is preserved.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
This commit is contained in:
Stephen J Day
2017-06-28 21:32:15 -07:00
parent 917914fcf5
commit a4fadc596b
42 changed files with 331 additions and 555 deletions
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11
content/store.go
View File

@@ -11,6 +11,7 @@ import (
"strconv"
"time"
"github.com/containerd/containerd/errdefs"
"github.com/containerd/containerd/log"
digest "github.com/opencontainers/go-digest"
"github.com/pkg/errors"
@@ -40,7 +41,7 @@ func (s *store) Info(ctx context.Context, dgst digest.Digest) (Info, error) {
fi, err := os.Stat(p)
if err != nil {
if os.IsNotExist(err) {
err = ErrNotFound("")
err = errors.Wrapf(errdefs.ErrNotFound, "content %v", dgst)
}
return Info{}, err
@@ -62,7 +63,7 @@ func (s *store) Reader(ctx context.Context, dgst digest.Digest) (io.ReadCloser,
fp, err := os.Open(s.blobPath(dgst))
if err != nil {
if os.IsNotExist(err) {
err = ErrNotFound("")
err = errors.Wrapf(errdefs.ErrNotFound, "content %v", dgst)
}
return nil, err
}
@@ -85,7 +86,7 @@ func (cs *store) Delete(ctx context.Context, dgst digest.Digest) error {
return err
}
return ErrNotFound("")
return errors.Wrapf(errdefs.ErrNotFound, "content %v", dgst)
}
return nil
@@ -232,7 +233,7 @@ func (s *store) Writer(ctx context.Context, ref string, total int64, expected di
if expected != "" {
p := s.blobPath(expected)
if _, err := os.Stat(p); err == nil {
return nil, ErrExists("")
return nil, errors.Wrapf(errdefs.ErrAlreadyExists, "content %v", expected)
}
}
@@ -329,7 +330,7 @@ func (s *store) Abort(ctx context.Context, ref string) error {
root := s.ingestRoot(ref)
if err := os.RemoveAll(root); err != nil {
if os.IsNotExist(err) {
return ErrNotFound("")
return errors.Wrapf(errdefs.ErrNotFound, "ingest ref %q", ref)
}
return err