Export ServeJSON for serving error codes

This changeset provides a common http handler for serving errcodes. This should
unify http responses across webservices in the face of errors.

Several type assertions have been added, as well, to ensure the error interface
is implemented.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
This commit is contained in:
Stephen J Day 2015-07-16 11:35:02 -07:00
parent 92aa378df4
commit 86ffe515df
4 changed files with 65 additions and 44 deletions

View file

@ -16,6 +16,8 @@ type ErrorCoder interface {
// and the integer format may change and should *never* be exported. // and the integer format may change and should *never* be exported.
type ErrorCode int type ErrorCode int
var _ error = ErrorCode(0)
// ErrorCode just returns itself // ErrorCode just returns itself
func (ec ErrorCode) ErrorCode() ErrorCode { func (ec ErrorCode) ErrorCode() ErrorCode {
return ec return ec
@ -93,6 +95,8 @@ type Error struct {
// variable substitution right before showing the message to the user // variable substitution right before showing the message to the user
} }
var _ error = Error{}
// ErrorCode returns the ID/Value of this Error // ErrorCode returns the ID/Value of this Error
func (e Error) ErrorCode() ErrorCode { func (e Error) ErrorCode() ErrorCode {
return e.Code return e.Code
@ -163,6 +167,8 @@ func ParseErrorCode(value string) ErrorCode {
// for use within the application. // for use within the application.
type Errors []error type Errors []error
var _ error = Errors{}
func (errs Errors) Error() string { func (errs Errors) Error() string {
switch len(errs) { switch len(errs) {
case 0: case 0:

View file

@ -0,0 +1,44 @@
package errcode
import (
"encoding/json"
"net/http"
)
// ServeJSON attempts to serve the errcode in a JSON envelope. It marshals err
// and sets the content-type header to 'application/json'. It will handle
// ErrorCoder and Errors, and if necessary will create an envelope.
func ServeJSON(w http.ResponseWriter, err error) error {
w.Header().Set("Content-Type", "application/json; charset=utf-8")
var sc int
switch errs := err.(type) {
case Errors:
if len(errs) < 1 {
break
}
if err, ok := errs[0].(ErrorCoder); ok {
sc = err.ErrorCode().Descriptor().HTTPStatusCode
}
case ErrorCoder:
sc = errs.ErrorCode().Descriptor().HTTPStatusCode
err = Errors{err} // create an envelope.
default:
// We just have an unhandled error type, so just place in an envelope
// and move along.
err = Errors{err}
}
if sc == 0 {
sc = http.StatusInternalServerError
}
w.WriteHeader(sc)
if err := json.NewEncoder(w).Encode(err); err != nil {
return err
}
return nil
}

View file

@ -379,7 +379,9 @@ func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
context.Errors = append(context.Errors, v2.ErrorCodeNameInvalid.WithDetail(err)) context.Errors = append(context.Errors, v2.ErrorCodeNameInvalid.WithDetail(err))
} }
serveJSON(w, context.Errors) if err := errcode.ServeJSON(w, context.Errors); err != nil {
ctxu.GetLogger(context).Errorf("error serving error json: %v (from %v)", err, context.Errors)
}
return return
} }
@ -393,7 +395,9 @@ func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
ctxu.GetLogger(context).Errorf("error initializing repository middleware: %v", err) ctxu.GetLogger(context).Errorf("error initializing repository middleware: %v", err)
context.Errors = append(context.Errors, errcode.ErrorCodeUnknown.WithDetail(err)) context.Errors = append(context.Errors, errcode.ErrorCodeUnknown.WithDetail(err))
serveJSON(w, context.Errors) if err := errcode.ServeJSON(w, context.Errors); err != nil {
ctxu.GetLogger(context).Errorf("error serving error json: %v (from %v)", err, context.Errors)
}
return return
} }
} }
@ -405,7 +409,9 @@ func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
if context.Errors.Len() > 0 { if context.Errors.Len() > 0 {
app.logError(context, context.Errors) app.logError(context, context.Errors)
serveJSON(w, context.Errors) if err := errcode.ServeJSON(w, context.Errors); err != nil {
ctxu.GetLogger(context).Errorf("error serving error json: %v (from %v)", err, context.Errors)
}
} }
}) })
} }
@ -482,11 +488,9 @@ func (app *App) authorized(w http.ResponseWriter, r *http.Request, context *Cont
// base route is accessed. This section prevents us from making // base route is accessed. This section prevents us from making
// that mistake elsewhere in the code, allowing any operation to // that mistake elsewhere in the code, allowing any operation to
// proceed. // proceed.
if err := errcode.ServeJSON(w, v2.ErrorCodeUnauthorized); err != nil {
var errs errcode.Errors ctxu.GetLogger(context).Errorf("error serving error json: %v (from %v)", err, context.Errors)
errs = append(errs, v2.ErrorCodeUnauthorized) }
serveJSON(w, errs)
return fmt.Errorf("forbidden: no repository name") return fmt.Errorf("forbidden: no repository name")
} }
} }
@ -498,9 +502,9 @@ func (app *App) authorized(w http.ResponseWriter, r *http.Request, context *Cont
// Add the appropriate WWW-Auth header // Add the appropriate WWW-Auth header
err.ServeHTTP(w, r) err.ServeHTTP(w, r)
var errs errcode.Errors if err := errcode.ServeJSON(w, v2.ErrorCodeUnauthorized.WithDetail(accessRecords)); err != nil {
errs = append(errs, v2.ErrorCodeUnauthorized.WithDetail(accessRecords)) ctxu.GetLogger(context).Errorf("error serving error json: %v (from %v)", err, context.Errors)
serveJSON(w, errs) }
default: default:
// This condition is a potential security problem either in // This condition is a potential security problem either in
// the configuration or whatever is backing the access // the configuration or whatever is backing the access

View file

@ -1,43 +1,10 @@
package handlers package handlers
import ( import (
"encoding/json"
"io" "io"
"net/http" "net/http"
"github.com/docker/distribution/registry/api/errcode"
) )
// serveJSON marshals v and sets the content-type header to
// 'application/json'. If a different status code is required, call
// ResponseWriter.WriteHeader before this function.
func serveJSON(w http.ResponseWriter, v interface{}) error {
w.Header().Set("Content-Type", "application/json; charset=utf-8")
sc := http.StatusInternalServerError
if errs, ok := v.(errcode.Errors); ok && len(errs) > 0 {
if err, ok := errs[0].(errcode.ErrorCoder); ok {
if sc2 := err.ErrorCode().Descriptor().HTTPStatusCode; sc2 != 0 {
sc = sc2
}
}
} else if err, ok := v.(errcode.ErrorCoder); ok {
if sc2 := err.ErrorCode().Descriptor().HTTPStatusCode; sc2 != 0 {
sc = sc2
}
}
w.WriteHeader(sc)
enc := json.NewEncoder(w)
if err := enc.Encode(v); err != nil {
return err
}
return nil
}
// closeResources closes all the provided resources after running the target // closeResources closes all the provided resources after running the target
// handler. // handler.
func closeResources(handler http.Handler, closers ...io.Closer) http.Handler { func closeResources(handler http.Handler, closers ...io.Closer) http.Handler {