Implement basic admission control framework

plugin/pkg/admission/admit/admission.go

@@ -0,0 +1,38 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package admit
+
+import (
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/admission"
+	"io"
+)
+
+func init() {
+	admission.RegisterPlugin("AlwaysAdmit", func(config io.Reader) (admission.Interface, error) { return NewAlwaysAdmit(), nil })
+}
+
+// alwaysAdmit is an implementation of admission.Interface which always says yes to an admit request.
+// It is useful in tests and when using kubernetes in an open manner.
+type alwaysAdmit struct{}
+
+func (alwaysAdmit) Admit(a admission.Attributes) (err error) {
+	return nil
+}
+
+func NewAlwaysAdmit() admission.Interface {
+	return new(alwaysAdmit)
+}

plugin/pkg/admission/deny/admission.go

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+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package deny
+
+import (
+	"errors"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/admission"
+	"io"
+)
+
+func init() {
+	admission.RegisterPlugin("AlwaysDeny", func(config io.Reader) (admission.Interface, error) { return NewAlwaysDeny(), nil })
+}
+
+// alwaysDeny is an implementation of admission.Interface which always says no to an admission request.
+// It is useful in unit tests to force an operation to be forbidden.
+type alwaysDeny struct{}
+
+func (alwaysDeny) Admit(a admission.Attributes) (err error) {
+	return errors.New("You shall not pass!")
+}
+
+func NewAlwaysDeny() admission.Interface {
+	return new(alwaysDeny)
+}