Implementing conversion
With our model for conversion in place, it’s time to actually implement
the conversion functions. We’ll put them in a file called
cronjob_conversion.go
next to our cronjob_types.go
file, to avoid
cluttering up our main types file with extra functions.
Hub…
First, we’ll implement the hub. We’ll choose the v1 version as the hub:
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
Implementing the hub method is pretty easy – we just have to add an empty
method called Hub()
to serve as a
marker.
We could also just put this inline in our cronjob_types.go
file.
// Hub marks this type as a conversion hub.
func (*CronJob) Hub() {}
… and Spokes
Then, we’ll implement our spoke, the v2 version:
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 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"
)
Our “spoke” versions need to implement the
Convertible
interface. Namely, they’ll need ConvertTo
and ConvertFrom
methods to convert to/from
the hub version.
ConvertTo is expected to modify its argument to contain the converted object. Most of the conversion is straightforward copying, except for converting our changed field.
// ConvertTo converts this CronJob to the Hub version (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
The rest of the conversion is pretty rote.
// 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 is expected to modify its receiver to contain the converted object. Most of the conversion is straightforward copying, except for converting our changed field.
// ConvertFrom converts from the Hub version (v1) to this version.
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
}
Now that we’ve got our conversions in place, all that we need to do is wire up our main to serve the webhook!