实现转换

采用的转换模型已经就绪，就可以开始实现转换函数了。我们将这些函数放置在 cronjob_conversion.go 文件中，cronjob_conversion.go 文件和 cronjob_types.go 文件同目录，以避免我们主要的类型文件和额外的方法产生混乱。

Hub...

首先，我们需要实现 hub 接口。我们会选择 v1 版本作为 hub 的一个实现：

project/api/v1/cronjob_conversion.go

Apache License

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 v1

实现 hub 方法相当容易 -- 我们只需要添加一个叫做 Hub() 的空方法来作为一个标记。我们也可以将这行代码放到 cronjob_types.go 文件中。

// Hub 标记这个类型是一个用来转换的 hub。
func (*CronJob) Hub() {}

... 然后 Spokes

然后，我们需要实现我们的 spoke 接口，例如 v2 版本：

project/api/v2/cronjob_conversion.go

Apache License

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

package v2

Imports

For imports, we’ll need the controller-runtime conversion package, plus the API version for our hub type (v1), and finally some of the standard packages.

import (
	"fmt"
	"strings"

	"sigs.k8s.io/controller-runtime/pkg/conversion"

	"tutorial.kubebuilder.io/project/api/v1"
)

我们的 “spoke” 版本需要实现 Convertible 接口。顾名思义，它需要实现 ConvertTo 从（其它版本）向 hub 版本转换，ConvertFrom 实现从 hub 版本转换到（其他版本）。

ConvertTo 期望修改其参数以包含转换后的对象。大部分转换都是直接赋值，除了那些发生变化的 field。

// ConvertTo 转换 CronJob 到 Hub 版本 (v1).
func (src *CronJob) ConvertTo(dstRaw conversion.Hub) error {
	dst := dstRaw.(*v1.CronJob)

	sched := src.Spec.Schedule
	scheduleParts := []string{"*", "*", "*", "*", "*"}
	if sched.Minute != nil {
		scheduleParts[0] = string(*sched.Minute)
	}
	if sched.Hour != nil {
		scheduleParts[1] = string(*sched.Hour)
	}
	if sched.DayOfMonth != nil {
		scheduleParts[2] = string(*sched.DayOfMonth)
	}
	if sched.Month != nil {
		scheduleParts[3] = string(*sched.Month)
	}
	if sched.DayOfWeek != nil {
		scheduleParts[4] = string(*sched.DayOfWeek)
	}
	dst.Spec.Schedule = strings.Join(scheduleParts, " ")

rote conversion

剩下的转换都相当机械。

	// ObjectMeta
	dst.ObjectMeta = src.ObjectMeta

	// Spec
	dst.Spec.StartingDeadlineSeconds = src.Spec.StartingDeadlineSeconds
	dst.Spec.ConcurrencyPolicy = v1.ConcurrencyPolicy(src.Spec.ConcurrencyPolicy)
	dst.Spec.Suspend = src.Spec.Suspend
	dst.Spec.JobTemplate = src.Spec.JobTemplate
	dst.Spec.SuccessfulJobsHistoryLimit = src.Spec.SuccessfulJobsHistoryLimit
	dst.Spec.FailedJobsHistoryLimit = src.Spec.FailedJobsHistoryLimit

	// Status
	dst.Status.Active = src.Status.Active
	dst.Status.LastScheduleTime = src.Status.LastScheduleTime

	return nil
}

ConvertFrom 期望修改其接收者以包含转换后的对象。大部分转换都是直接赋值，除了那些发生变化的 field。

// ConvertFrom 从 Hub 版本 (v1) 转换到这个版本。
func (dst *CronJob) ConvertFrom(srcRaw conversion.Hub) error {
	src := srcRaw.(*v1.CronJob)

	schedParts := strings.Split(src.Spec.Schedule, " ")
	if len(schedParts) != 5 {
		return fmt.Errorf("invalid schedule: not a standard 5-field schedule")
	}
	partIfNeeded := func(raw string) *CronField {
		if raw == "*" {
			return nil
		}
		part := CronField(raw)
		return &part
	}
	dst.Spec.Schedule.Minute = partIfNeeded(schedParts[0])
	dst.Spec.Schedule.Hour = partIfNeeded(schedParts[1])
	dst.Spec.Schedule.DayOfMonth = partIfNeeded(schedParts[2])
	dst.Spec.Schedule.Month = partIfNeeded(schedParts[3])
	dst.Spec.Schedule.DayOfWeek = partIfNeeded(schedParts[4])

rote conversion

The rest of the conversion is pretty rote.

	// ObjectMeta
	dst.ObjectMeta = src.ObjectMeta

	// Spec
	dst.Spec.StartingDeadlineSeconds = src.Spec.StartingDeadlineSeconds
	dst.Spec.ConcurrencyPolicy = ConcurrencyPolicy(src.Spec.ConcurrencyPolicy)
	dst.Spec.Suspend = src.Spec.Suspend
	dst.Spec.JobTemplate = src.Spec.JobTemplate
	dst.Spec.SuccessfulJobsHistoryLimit = src.Spec.SuccessfulJobsHistoryLimit
	dst.Spec.FailedJobsHistoryLimit = src.Spec.FailedJobsHistoryLimit

	// Status
	dst.Status.Active = src.Status.Active
	dst.Status.LastScheduleTime = src.Status.LastScheduleTime

	return nil
}

现在我们的转换方法已经就绪，我们要做的就是启动我们的 main 方法来运行 webhook。