Add affinity settings in viz and jaeger chart

[naing2victor]

Add nodeAffinity for deployment template to linkerd-viz and linkerd-jaeger charts

Fixes #10680

[adleong]

Thanks, @naing2victor!

I noticed that you're setting the component and label values which are used by podAntiAffinity, not nodeAffinity. What do you think of adding

# -- Enables Pod Anti Affinity logic to balance the placement of replicas
# across hosts and zones for High Availability.
# Enable this only when you have multiple replicas of components.
enablePodAntiAffinity: false

to the values.yaml since we're setting those component and label values anyway. That makes it consistent with the other extensions as well.

[naing2victor]

@adleong Thank you for your feedback. I can see that linkerd-viz chart is already implemented with podAntiAffinity. We'll only need to apply for linkerd-jaeger chart. Adding enablePodAntiAffinity may also need to variabilize the replicas for each component. May I know how would you suggest for the value usage.

Would it be better if we separate the variable by the component. For example,

replicas: {{.Values.jaegerInjector.replicas}}
replicas: {{.Values.collector.replicas}}
replicas: {{.Values.jaeger.replicas}}

Or just using 1 value for all the components.

replicas: {{.Values.replicas}}

[adleong]

I'd recommend having a separate replicas value for each component (which is what we do in linkerd-viz). However, the exception to that is that increasing the number of replicas of the jaeger component could be problematic since this is a stateful trace backend; so we may want to leave that one hardcoded at 1 replica.

[naing2victor]

I've added enablePodAntiAffinity and make replicas values to get from values file.

[alpeb]

If you try rendering the templates with enablePodAntiAffinity=true you'll see there's a problem. I believe the issue is not passing $tree into the linkerd.affinity include.