mirror of https://github.com/k3s-io/k3s
146 lines
3.7 KiB
Go
146 lines
3.7 KiB
Go
/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package schedulingpolicy
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"strings"
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"time"
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"k8s.io/apimachinery/pkg/api/errors"
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"k8s.io/apimachinery/pkg/runtime"
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"k8s.io/apimachinery/pkg/runtime/schema"
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"k8s.io/apiserver/pkg/util/webhook"
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"k8s.io/client-go/rest"
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"k8s.io/kubernetes/pkg/api"
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)
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// policyUndefinedError represents an undefined response from the policy
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// engine. This typically means the relevant policy has not been loaded into
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// the engine.
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type policyUndefinedError struct{}
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func (policyUndefinedError) Error() string {
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return "policy decision is undefined"
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}
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// policyEngineQuery represents a single query against the policy engine.
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type policyEngineQuery struct {
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client *rest.RESTClient
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retryBackoff time.Duration
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obj runtime.Object
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gvk schema.GroupVersionKind
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}
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// newPolicyEngineQuery returns a policyEngineQuery that can be executed.
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func newPolicyEngineQuery(client *rest.RESTClient, retryBackoff time.Duration, obj runtime.Object, gvk schema.GroupVersionKind) *policyEngineQuery {
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return &policyEngineQuery{
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client: client,
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retryBackoff: retryBackoff,
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obj: obj,
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gvk: gvk,
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}
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}
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// Do returns the result of the policy engine query. If the policy decision is
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// undefined or an unknown error occurs, err is non-nil. Otherwise, result is
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// non-nil and contains the result of policy evaluation.
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func (query *policyEngineQuery) Do() (decision *policyDecision, err error) {
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bs, err := query.encode()
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if err != nil {
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return nil, err
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}
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var result rest.Result
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err = webhook.WithExponentialBackoff(query.retryBackoff, func() error {
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result = query.client.Post().
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Body(bs).
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Do()
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return result.Error()
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})
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if err != nil {
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if errors.IsNotFound(err) {
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return nil, policyUndefinedError{}
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}
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return nil, err
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}
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return decodeResult(result)
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}
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// encode returns the encoded version of the query's runtime.Object.
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func (query *policyEngineQuery) encode() ([]byte, error) {
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var info runtime.SerializerInfo
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infos := api.Codecs.SupportedMediaTypes()
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for i := range infos {
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if infos[i].MediaType == "application/json" {
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info = infos[i]
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}
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}
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if info.Serializer == nil {
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return nil, fmt.Errorf("serialization not supported")
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}
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codec := api.Codecs.EncoderForVersion(info.Serializer, query.gvk.GroupVersion())
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var buf bytes.Buffer
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if err := codec.Encode(query.obj, &buf); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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// policyDecision represents a response from the policy engine.
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type policyDecision struct {
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Errors []string `json:"errors,omitempty"`
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Annotations map[string]string `json:"annotations,omitempty"`
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}
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// Error returns an error if the policy raised an error.
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func (d *policyDecision) Error() error {
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if len(d.Errors) == 0 {
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return nil
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}
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return fmt.Errorf("reason(s): %v", strings.Join(d.Errors, "; "))
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}
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func decodeResult(result rest.Result) (*policyDecision, error) {
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bs, err := result.Raw()
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if err != nil {
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return nil, err
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}
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buf := bytes.NewBuffer(bs)
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var decision policyDecision
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if err := json.NewDecoder(buf).Decode(&decision); err != nil {
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return nil, err
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}
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return &decision, nil
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}
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