Kubernetes advanced

// listReplicaSets returns a slice of RSes the given deployment targets.
// Note that this does NOT attempt to reconcile ControllerRef (adopt/orphan),
// because only the controller itself should do that.
// However, it does filter out anything whose ControllerRef doesn't match.
func listReplicaSets(deployment *appsv1.Deployment, getRSList rsListFunc) ([]*appsv1.ReplicaSet, error) {
	// TODO: Right now we list replica sets by their labels. We should list them by selector, i.e. the replica set's selector
	//       should be a superset of the deployment's selector, see https://github.com/kubernetes/kubernetes/issues/19830.
	namespace := deployment.Namespace
	selector, err := metav1.LabelSelectorAsSelector(deployment.Spec.Selector)
	if err != nil {
		return nil, err
	}
	options := metav1.ListOptions{LabelSelector: selector.String()}
	all, err := getRSList(namespace, options)
	if err != nil {
		return nil, err
	}
	// Only include those whose ControllerRef matches the Deployment.
	owned := make([]*appsv1.ReplicaSet, 0, len(all))
	for _, rs := range all {
		if metav1.IsControlledBy(rs, deployment) {
			owned = append(owned, rs)
		}
	}
	return owned, nil
}

// equalIgnoreHash returns true if two given podTemplateSpec are equal, ignoring the diff in value of Labels[pod-template-hash]
// We ignore pod-template-hash because:
// 1. The hash result would be different upon podTemplateSpec API changes
//    (e.g. the addition of a new field will cause the hash code to change)
// 2. The deployment template won't have hash labels
func equalIgnoreHash(template1, template2 *corev1.PodTemplateSpec) bool {
	t1Copy := template1.DeepCopy()
	t2Copy := template2.DeepCopy()
	// Remove hash labels from template.Labels before comparing
	delete(t1Copy.Labels, appsv1.DefaultDeploymentUniqueLabelKey)
	delete(t2Copy.Labels, appsv1.DefaultDeploymentUniqueLabelKey)
	return apiequality.Semantic.DeepEqual(t1Copy, t2Copy)
}

func (r *DeploymentRollbacker) Rollback(obj runtime.Object, updatedAnnotations map[string]string, toRevision int64, dryRunStrategy cmdutil.DryRunStrategy) (string, error) {
	if toRevision < 0 {
		return "", revisionNotFoundErr(toRevision)
	}
	accessor, err := meta.Accessor(obj)
	if err != nil {
		return "", fmt.Errorf("failed to create accessor for kind %v: %s", obj.GetObjectKind(), err.Error())
	}
	name := accessor.GetName()
	namespace := accessor.GetNamespace()

	// TODO: Fix this after kubectl has been removed from core. It is not possible to convert the runtime.Object
	// to the external appsv1 Deployment without round-tripping through an internal version of Deployment. We're
	// currently getting rid of all internal versions of resources. So we specifically request the appsv1 version
	// here. This follows the same pattern as for DaemonSet and StatefulSet.
	deployment, err := r.c.AppsV1().Deployments(namespace).Get(context.TODO(), name, metav1.GetOptions{})
	if err != nil {
		return "", fmt.Errorf("failed to retrieve Deployment %s: %v", name, err)
	}

	rsForRevision, err := deploymentRevision(deployment, r.c, toRevision)
	if err != nil {
		return "", err
	}
	if dryRunStrategy == cmdutil.DryRunClient {
		return printTemplate(&rsForRevision.Spec.Template)
	}
	if deployment.Spec.Paused {
		return "", fmt.Errorf("you cannot rollback a paused deployment; resume it first with 'kubectl rollout resume deployment/%s' and try again", name)
	}

	// Skip if the revision already matches current Deployment
	if equalIgnoreHash(&rsForRevision.Spec.Template, &deployment.Spec.Template) {
		return fmt.Sprintf("%s (current template already matches revision %d)", rollbackSkipped, toRevision), nil
	}

	// remove hash label before patching back into the deployment
	delete(rsForRevision.Spec.Template.Labels, appsv1.DefaultDeploymentUniqueLabelKey)

	// compute deployment annotations
	annotations := map[string]string{}
	for k := range annotationsToSkip {
		if v, ok := deployment.Annotations[k]; ok {
			annotations[k] = v
		}
	}
	for k, v := range rsForRevision.Annotations {
		if !annotationsToSkip[k] {
			annotations[k] = v
		}
	}

	// make patch to restore
	patchType, patch, err := getDeploymentPatch(&rsForRevision.Spec.Template, annotations)
	if err != nil {
		return "", fmt.Errorf("failed restoring revision %d: %v", toRevision, err)
	}

	patchOptions := metav1.PatchOptions{}
	if dryRunStrategy == cmdutil.DryRunServer {
		patchOptions.DryRun = []string{metav1.DryRunAll}
	}
	// Restore revision
	if _, err = r.c.AppsV1().Deployments(namespace).Patch(context.TODO(), name, patchType, patch, patchOptions); err != nil {
		return "", fmt.Errorf("failed restoring revision %d: %v", toRevision, err)
	}
	return rollbackSuccess, nil
}

# setup autocomplete in bash into the current shell, bash-completion package should be installed first.
source <(kubectl completion bash) 
# add autocomplete permanently to your bash shell.
echo "source <(kubectl completion bash)" >> ~/.bashrc 

alias k=kubectl
complete -F __start_kubectl k

helm completion bash > /etc/bash_completion.d/helm

# List images per pods
kubectl get pods --all-namespaces -o jsonpath='{range .items[*]}{"\n"}{.metadata.name}{":\t"}{range .spec.containers[*]}{.image}{", "}{end}{end}' |\
sort
# Connect to node
kubectl debug node/{node-name} -it --image=mcr.microsoft.com/dotnet/runtime-deps:6.0

{{ if ((.Values.foo).bar) }}
{{ .Values.foo.bar }}
{{ end }}