Mutating Webhooks

Introduction

Mutating webhooks are most frequently used for setting default values. They can modify objects by creating a patch that will be sent back in the admission response.

Example Mutating Webhook

[Webhook(
    name: "pod-policy.neonkube.io",
    admissionReviewVersions: "v1",
    failurePolicy: "Ignore")]
[WebhookRule(
    apiGroups: V1Pod.KubeGroup,
    apiVersions: V1Pod.KubeApiVersion,
    operations: AdmissionOperations.Create | AdmissionOperations.Update,
    resources: V1Pod.KubePluralName,
    scope: "*")]
public class PodWebhook : MutatingWebhookBase<V1Pod>
{
    private bool modified = false;

    public override async Task<MutationResult> CreateAsync(V1Pod entity, bool dryRun, CancellationToken cancellationToken = default)
    {
        if (modified)
        {
            return await Task.FromResult(MutationResult.Modified(entity));
        }

        return await Task.FromResult(MutationResult.NoChanges());
    }

    public override async Task<MutationResult> UpdateAsync(V1Pod entity, V1Pod oldEntity, bool dryRun, CancellationToken cancellationToken = default)
    {
        if (modified)
        {
            return await Task.FromResult(MutationResult.Modified(entity));
        }

        return await Task.FromResult(MutationResult.NoChanges());
    }
}