Kubernetes Fake Client 不处理 ObjectMeta 中的 GenerateName

Question

当使用 Kubernetes Fake Client to write unit tests, I noticed that it fails to create two identical objects which have their ObjectMeta.GenerateName 字段设置为某个字符串时。一个真正的集群接受这个规范并为每个对象生成一个唯一的名称。

运行以下测试代码：

package main

import (
    "context"
    "testing"

    "github.com/stretchr/testify/assert"
    corev1 "k8s.io/api/core/v1"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/client-go/kubernetes/fake"
)

func TestFake(t *testing.T) {
    ctx := context.Background()
    client := fake.NewSimpleClientset()

    _, err := client.CoreV1().Secrets("default").Create(ctx, &corev1.Secret{
        ObjectMeta: metav1.ObjectMeta{
            GenerateName: "generated",
        },
        StringData: map[string]string{"foo": "bar"},
    }, metav1.CreateOptions{})
    assert.NoError(t, err)

    _, err = client.CoreV1().Secrets("default").Create(ctx, &corev1.Secret{
        ObjectMeta: metav1.ObjectMeta{
            GenerateName: "generated",
        },
        StringData: map[string]string{"foo": "bar"},
    }, metav1.CreateOptions{})
    assert.NoError(t, err)
}

失败

--- FAIL: TestFake (0.00s)
    /Users/mihaitodor/Projects/kubernetes/main_test.go:44: 
            Error Trace:    main_test.go:44
            Error:          Received unexpected error:
                            secrets "" already exists
            Test:           TestFake
FAIL
FAIL    kubernetes  0.401s
FAIL

Answer 1

根据thisGitHub问题评论：

the fake clientset doesn't attempt to duplicate server-side behavior like validation, name generation, uid assignment, etc. if you want to test things like that, you can add reactors to mock that behavior.

要添加所需的反应器，我们可以在创建 corev1.Secret 对象之前插入以下代码：

client.PrependReactor(
    "create", "*",
    func(action k8sTesting.Action) (handled bool, ret runtime.Object, err error) {
        ret = action.(k8sTesting.CreateAction).GetObject()
        meta, ok := ret.(metav1.Object)
        if !ok {
            return
        }

        if meta.GetName() == "" && meta.GetGenerateName() != "" {
            meta.SetName(names.SimpleNameGenerator.GenerateName(meta.GetGenerateName()))
        }

        return
    },
)

里面有一些陷阱：

Clientset 包含嵌入的 Fake structure which has the PrependReactor method we need to call for this use case (there are a few others). This code here 在创建此类对象时被调用。
PrependReactor方法有3个参数：verb、resource和reaction。对于 verb、resource，我找不到任何命名常量，因此，在这种情况下，“create”和“secrets”（奇怪的是它不是“secret”）似乎是正确的值对于他们来说，如果我们想要超级具体，但是在这种情况下将 resource 设置为“*”应该是可以接受的。
reaction 参数的类型为 ReactionFunc, which takes an Action as a parameter and returns handled, ret and err. After some digging, I noticed that the action parameter will be cast to CreateAction, which has the GetObject() method that returns a runtime.Object instance, which can be cast to metav1.Object。该接口允许我们获取和设置底层对象的各种元数据字段。根据需要设置对象 Name 字段后，我们必须 return handled = false、ret = mutatedObject 和 err = nil 来指示调用代码执行剩余的反应器。
深入研究 apiserver 代码，我注意到 ObjectMeta.Name 字段 is generated from the ObjectMeta.GenerateName field using the names.SimpleNameGenerator.GenerateName 实用程序。

Kubernetes Fake Client 不处理 ObjectMeta 中的 GenerateName

Kubernetes Fake Client doesn't handle GenerateName in ObjectMeta

unit-testing

go

kubernetes

client-go