1/*
2Copyright 2018 The Kubernetes Authors.
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8    http://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17package options
18
19import (
20	"fmt"
21	"strings"
22
23	"github.com/spf13/pflag"
24
25	"k8s.io/apimachinery/pkg/util/sets"
26	"k8s.io/apiserver/pkg/admission"
27	"k8s.io/apiserver/pkg/server"
28	genericoptions "k8s.io/apiserver/pkg/server/options"
29	"k8s.io/client-go/informers"
30	"k8s.io/client-go/rest"
31	"k8s.io/component-base/featuregate"
32)
33
34// AdmissionOptions holds the admission options.
35// It is a wrap of generic AdmissionOptions.
36type AdmissionOptions struct {
37	// GenericAdmission holds the generic admission options.
38	GenericAdmission *genericoptions.AdmissionOptions
39	// DEPRECATED flag, should use EnabledAdmissionPlugins and DisabledAdmissionPlugins.
40	// They are mutually exclusive, specify both will lead to an error.
41	PluginNames []string
42}
43
44// NewAdmissionOptions creates a new instance of AdmissionOptions
45// Note:
46//  In addition it calls RegisterAllAdmissionPlugins to register
47//  all kube-apiserver admission plugins.
48//
49//  Provides the list of RecommendedPluginOrder that holds sane values
50//  that can be used by servers that don't care about admission chain.
51//  Servers that do care can overwrite/append that field after creation.
52func NewAdmissionOptions() *AdmissionOptions {
53	options := genericoptions.NewAdmissionOptions()
54	// register all admission plugins
55	RegisterAllAdmissionPlugins(options.Plugins)
56	// set RecommendedPluginOrder
57	options.RecommendedPluginOrder = AllOrderedPlugins
58	// set DefaultOffPlugins
59	options.DefaultOffPlugins = DefaultOffAdmissionPlugins()
60
61	return &AdmissionOptions{
62		GenericAdmission: options,
63	}
64}
65
66// AddFlags adds flags related to admission for kube-apiserver to the specified FlagSet
67func (a *AdmissionOptions) AddFlags(fs *pflag.FlagSet) {
68	fs.StringSliceVar(&a.PluginNames, "admission-control", a.PluginNames, ""+
69		"Admission is divided into two phases. "+
70		"In the first phase, only mutating admission plugins run. "+
71		"In the second phase, only validating admission plugins run. "+
72		"The names in the below list may represent a validating plugin, a mutating plugin, or both. "+
73		"The order of plugins in which they are passed to this flag does not matter. "+
74		"Comma-delimited list of: "+strings.Join(a.GenericAdmission.Plugins.Registered(), ", ")+".")
75	fs.MarkDeprecated("admission-control", "Use --enable-admission-plugins or --disable-admission-plugins instead. Will be removed in a future version.")
76	fs.Lookup("admission-control").Hidden = false
77
78	a.GenericAdmission.AddFlags(fs)
79}
80
81// Validate verifies flags passed to kube-apiserver AdmissionOptions.
82// Kube-apiserver verifies PluginNames and then call generic AdmissionOptions.Validate.
83func (a *AdmissionOptions) Validate() []error {
84	if a == nil {
85		return nil
86	}
87	var errs []error
88	if a.PluginNames != nil &&
89		(a.GenericAdmission.EnablePlugins != nil || a.GenericAdmission.DisablePlugins != nil) {
90		errs = append(errs, fmt.Errorf("admission-control and enable-admission-plugins/disable-admission-plugins flags are mutually exclusive"))
91	}
92
93	registeredPlugins := sets.NewString(a.GenericAdmission.Plugins.Registered()...)
94	for _, name := range a.PluginNames {
95		if !registeredPlugins.Has(name) {
96			errs = append(errs, fmt.Errorf("admission-control plugin %q is unknown", name))
97		}
98	}
99
100	errs = append(errs, a.GenericAdmission.Validate()...)
101
102	return errs
103}
104
105// ApplyTo adds the admission chain to the server configuration.
106// Kube-apiserver just call generic AdmissionOptions.ApplyTo.
107func (a *AdmissionOptions) ApplyTo(
108	c *server.Config,
109	informers informers.SharedInformerFactory,
110	kubeAPIServerClientConfig *rest.Config,
111	features featuregate.FeatureGate,
112	pluginInitializers ...admission.PluginInitializer,
113) error {
114	if a == nil {
115		return nil
116	}
117
118	if a.PluginNames != nil {
119		// pass PluginNames to generic AdmissionOptions
120		a.GenericAdmission.EnablePlugins, a.GenericAdmission.DisablePlugins = computePluginNames(a.PluginNames, a.GenericAdmission.RecommendedPluginOrder)
121	}
122
123	return a.GenericAdmission.ApplyTo(c, informers, kubeAPIServerClientConfig, features, pluginInitializers...)
124}
125
126// explicitly disable all plugins that are not in the enabled list
127func computePluginNames(explicitlyEnabled []string, all []string) (enabled []string, disabled []string) {
128	return explicitlyEnabled, sets.NewString(all...).Difference(sets.NewString(explicitlyEnabled...)).List()
129}
130