Rename Runtime to PlatformRuntime

This renames the runtime interface to PlatformRuntime to denote the
layer at which the runtime is being abstracted.  This should be used to
abstract different platforms that vary greatly and do not have full
compat with OCI based binary runtimes.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

services/tasks/local.go

@@ -79,14 +79,14 @@ func initFunc(ic *plugin.InitContext) (interface{}, error) {
 		return nil, err
 	}
 	cs := m.(*metadata.DB).ContentStore()
-	runtimes := make(map[string]runtime.Runtime)
+	runtimes := make(map[string]runtime.PlatformRuntime)
 	for _, rr := range rt {
 		ri, err := rr.Instance()
 		if err != nil {
 			log.G(ic.Context).WithError(err).Warn("could not load runtime instance due to initialization error")
 			continue
 		}
-		r := ri.(runtime.Runtime)
+		r := ri.(runtime.PlatformRuntime)
 		runtimes[r.ID()] = r
 	}
 
@@ -102,7 +102,7 @@ func initFunc(ic *plugin.InitContext) (interface{}, error) {
 }
 
 type local struct {
-	runtimes  map[string]runtime.Runtime
+	runtimes  map[string]runtime.PlatformRuntime
 	db        *metadata.DB
 	store     content.Store
 	publisher events.Publisher
@@ -625,7 +625,7 @@ func (l *local) getTaskFromContainer(ctx context.Context, container *containers.
 	return t, nil
 }
 
-func (l *local) getRuntime(name string) (runtime.Runtime, error) {
+func (l *local) getRuntime(name string) (runtime.PlatformRuntime, error) {
 	runtime, ok := l.runtimes[name]
 	if !ok {
 		return nil, status.Errorf(codes.NotFound, "unknown runtime %q", name)