66 lines
2.7 KiB
Go
66 lines
2.7 KiB
Go
/*
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Copyright 2022 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 etcd3
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import (
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"testing"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apiserver/pkg/apis/example"
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"k8s.io/apiserver/pkg/storage"
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)
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func TestLinearizedReadRevisionInvariant(t *testing.T) {
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// The etcd documentation [1] states that "linearized requests must go through the Raft consensus process."
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// A full round of Raft consensus adds a new item to the Raft log, some of which is surfaced by etcd as a
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// higher store revision in the response header. Kubernetes exposes this header revision in e.g. List calls,
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// so it is ultimately client-facing. By default, all the requests that our *etcd3.store{} issues are
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// linearized. However, this also includes *read* requests, and we would not expect non-mutating requests
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// against etcd to, by "go[ing] through the Raft consensus process," result in a higher resource version on
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// List calls. Today, the mechanism etcd uses to increment the store revision ensures that linearized reads
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// do *not* bump the key-value store revision. This test exists to ensure that we notice if this implementation
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// detail ever changes.
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// [1] https://etcd.io/docs/v3.5/learning/api_guarantees/#isolation-level-and-consistency-of-replicas
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ctx, store, etcdClient := testSetup(t)
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dir := "/testing"
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key := dir + "/testkey"
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out := &example.Pod{}
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obj := &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "foo", SelfLink: "testlink"}}
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if err := store.Create(ctx, key, obj, out, 0); err != nil {
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t.Fatalf("Set failed: %v", err)
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}
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originalRevision := out.ResourceVersion
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for i := 0; i < 5; i++ {
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if _, err := etcdClient.KV.Get(ctx, key); err != nil { // this is by default linearizable, the only option the client library exposes is WithSerializable() to make it *not* a linearized read
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t.Fatalf("failed to get key: %v", err)
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}
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}
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list := &example.PodList{}
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if err := store.GetList(ctx, dir, storage.ListOptions{Predicate: storage.Everything, Recursive: true}, list); err != nil {
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t.Errorf("Unexpected List error: %v", err)
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}
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finalRevision := list.ResourceVersion
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if originalRevision != finalRevision {
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t.Fatalf("original revision (%s) did not match final revision after linearized reads (%s)", originalRevision, finalRevision)
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}
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}
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