image removal: refactor part 2

Continue the refactoring of image removal.  I didn't manage to break all
the following changes into smaller and easier to digest commits due to
time constraints:

 * Return an error slice instead of a single error. Use multierror only
   in the client/frontend.  Reflect that in the types.

 * Use the batch image removal in the client while preserving the more
   rest-idiomatic single-image removal endpoint.

 * Add a new handler for the single-image removal endpoint to make it
   share the same code as the batch endpoint.

 * Expose bindings for the single and batch endpoints, so we can
   properly test them.

 * Add several convenience functions for error handling to
   pkg/errorhandling.

 * Set the correct error type in libpod to set the exit code to 2 when
   one or more containers are using an image.

 * Massage the bindings tests a bit and tackle compilation errors.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

pkg/api/handlers/libpod/images.go

@@ -23,6 +23,7 @@ import (
 	"github.com/containers/libpod/pkg/api/handlers/utils"
 	"github.com/containers/libpod/pkg/domain/entities"
 	"github.com/containers/libpod/pkg/domain/infra/abi"
+	"github.com/containers/libpod/pkg/errorhandling"
 	"github.com/containers/libpod/pkg/util"
 	utils2 "github.com/containers/libpod/utils"
 	"github.com/gorilla/schema"
@@ -700,8 +701,8 @@ func SearchImages(w http.ResponseWriter, r *http.Request) {
 	utils.WriteResponse(w, http.StatusOK, reports)
 }
 
-// ImagesRemove is the endpoint for image removal.
-func ImagesRemove(w http.ResponseWriter, r *http.Request) {
+// ImagesBatchRemove is the endpoint for batch image removal.
+func ImagesBatchRemove(w http.ResponseWriter, r *http.Request) {
 	runtime := r.Context().Value("runtime").(*libpod.Runtime)
 	decoder := r.Context().Value("decoder").(*schema.Decoder)
 	query := struct {
@@ -722,7 +723,49 @@ func ImagesRemove(w http.ResponseWriter, r *http.Request) {
 	opts := entities.ImageRemoveOptions{All: query.All, Force: query.Force}
 
 	imageEngine := abi.ImageEngine{Libpod: runtime}
-	rmReport, rmError := imageEngine.Remove(r.Context(), query.Images, opts)
-	report := handlers.LibpodImagesRemoveReport{ImageRemoveReport: *rmReport, Error: rmError.Error()}
+	rmReport, rmErrors := imageEngine.Remove(r.Context(), query.Images, opts)
+
+	strErrs := errorhandling.ErrorsToStrings(rmErrors)
+	report := handlers.LibpodImagesRemoveReport{ImageRemoveReport: *rmReport, Errors: strErrs}
 	utils.WriteResponse(w, http.StatusOK, report)
 }
+
+// ImagesRemove is the endpoint for removing one image.
+func ImagesRemove(w http.ResponseWriter, r *http.Request) {
+	runtime := r.Context().Value("runtime").(*libpod.Runtime)
+	decoder := r.Context().Value("decoder").(*schema.Decoder)
+	query := struct {
+		Force bool `schema:"force"`
+	}{
+		Force: false,
+	}
+
+	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
+		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
+			errors.Wrapf(err, "failed to parse parameters for %s", r.URL.String()))
+		return
+	}
+
+	opts := entities.ImageRemoveOptions{Force: query.Force}
+	imageEngine := abi.ImageEngine{Libpod: runtime}
+	rmReport, rmErrors := imageEngine.Remove(r.Context(), []string{utils.GetName(r)}, opts)
+
+	// In contrast to batch-removal, where we're only setting the exit
+	// code, we need to have another closer look at the errors here and set
+	// the appropriate http status code.
+
+	switch rmReport.ExitCode {
+	case 0:
+		report := handlers.LibpodImagesRemoveReport{ImageRemoveReport: *rmReport, Errors: []string{}}
+		utils.WriteResponse(w, http.StatusOK, report)
+	case 1:
+		// 404 - no such image
+		utils.Error(w, "error removing image", http.StatusNotFound, errorhandling.JoinErrors(rmErrors))
+	case 2:
+		// 409 - conflict error (in use by containers)
+		utils.Error(w, "error removing image", http.StatusConflict, errorhandling.JoinErrors(rmErrors))
+	default:
+		// 500 - internal error
+		utils.Error(w, "failed to remove image", http.StatusInternalServerError, errorhandling.JoinErrors(rmErrors))
+	}
+}

pkg/api/handlers/types.go

@@ -41,7 +41,7 @@ type LibpodImagesPullReport struct {
 type LibpodImagesRemoveReport struct {
 	entities.ImageRemoveReport
 	// Image removal requires is to return data and an error.
-	Error string
+	Errors []string
 }
 
 type ContainersPruneReport struct {