[feature request]support yurthub component work in specified namespace

[rambohe-ch]

What would you like to be added:
yurthub component should be deployed in kube-system namespace. as you known, kube-system namespace is used for K8s components, so some users have requested that yurthub can be deployed in specified namespace.

Why is this needed:
improve the deployment flexibility of OpenYurt component.

others
/kind feature

[YTGhost]

What exactly does this need do? Can't yurthub currently run under another namespace? Is there anything else that needs to be changed?

[rambohe-ch]

Does this mean we need to add a new flag named ResourceNamespace to yurthub and set the value to LeaderElection.ResourceNamespace? Is there anything else that needs to be changed?

@YTGhost I think that one component works in a specified namespace, the following two jobs maybe included:

1. the deployment of this component should be improved, the namespace for this component can be specified in the helm values.yaml or command tool(like yurtadm) parameter.
2. improve kube-system hard code in the component, and the namespace can be specified as a parameter for the component.

[YTGhost]

Does this mean we need to add a new flag named ResourceNamespace to yurthub and set the value to LeaderElection.ResourceNamespace? Is there anything else that needs to be changed?

@YTGhost I think that one component works in a specified namespace, the following two jobs maybe included:

1. the deployment of this component should be improved, the namespace for this component can be specified in the helm values.yaml or command tool(like yurtadm) parameter.
2. improve kube-system hard code in the component, and the namespace can be specified as a parameter for the component.

I see. Maybe I can take this work after migrate the service topology controller.

[huweihuang]

yurthub component should be deployed in kube-system namespace. as you known, kube-system namespace is used for K8s components, so some users have requested that yurthub can be deployed in specified namespace.

is there only update the yurthub component to specified namespace or include the all openyurt component in the same specified namespace? @rambohe-ch

[huweihuang]

may I take this work? @rambohe-ch

[rambohe-ch]

yurthub component should be deployed in kube-system namespace. as you known, kube-system namespace is used for K8s components, so some users have requested that yurthub can be deployed in specified namespace.

is there only update the yurthub component to specified namespace or include the all openyurt component in the same specified namespace? @rambohe-ch

@huweihuang yes, only adapt for yurthub, and we will track other components in new issues.

[rambohe-ch]

/assign @huweihuang

[huweihuang]

if we set a specified namespace for yurthub and the other openyurt component, What is the appropriate name of the namespace? if the user didn't set the specified namespace , can use openyurt as default namespace which been set in yurthub.yaml? @rambohe-ch

[rambohe-ch]

if we set a specified namespace for yurthub and the other openyurt component, What is the appropriate name of the namespace? if the user didn't set the specified namespace , can use openyurt as default namespace which been set in yurthub.yaml? @rambohe-ch

@huweihuang I think that default namespace should be kube-system, so we keep the consistency with the old version.

[huweihuang]

ok， if the all openyurt component set a specified namespace, shall we use openyurt insteads of kube-system as default namespace? @rambohe-ch

[rambohe-ch]

ok， if the all openyurt component set a specified namespace, shall we use openyurt insteads of kube-system as default namespace? @rambohe-ch

@huweihuang maybe we can use the specified namespace as default namespace, not openyurt.