Implementing conversion

With our model for conversion in place, it's time to actually implement the conversion functions. We'll create a conversion webhook for our CronJob API version v1 (Hub) to Spoke our CronJob API version v2 see:

kubebuilder create webhook --group batch --version v1 --kind CronJob --conversion --spoke v2

The above command will generate the cronjob_conversion.go next to our cronjob_types.go file, to avoid cluttering up our main types file with extra functions.

Unlike defaulting and validation webhooks, conversion webhooks do not support custom paths via command-line flags. Conversion webhooks use CRD conversion configuration (.spec.conversion.webhook.clientConfig.service.path in the CRD) rather than webhook marker annotations. The path for conversion webhooks is managed differently and cannot be customized through kubebuilder flags.

Hub...

First, we'll implement the hub. We'll choose the v1 version as the hub:

{{#literatego ./testdata/project/api/v1/cronjob_conversion.go}}

... and Spokes

Then, we'll implement our spoke, the v2 version:

{{#literatego ./testdata/project/api/v2/cronjob_conversion.go}}

Now that we've got our conversions in place, all that we need to do is wire up our main to serve the webhook!