Helm chart should support namespace, ambassador_id, and SINGLE_NAMESPACE

[kflynn]

Right now, the Helm chart totally ignores namespace. That's obviously a problem.

Realistically, the chart needs to also support ambassador_id and AMBASSADOR_SINGLE_NAMESPACE.

[endrec]

the Helm chart totally ignores namespace
As far as I know (though I'm just started with Helm charts), if the templates do not set the namespace, everything will be rendered in .Release.Namespace. This is the case with the ambassador chart.

Supporting ambassador_id and AMBASSADOR_SINGLE_NAMESPACE raises some questions:

• does ambassador_id makes sense when AMBASSADOR_SINGLE_NAMESPACE is set?
• what value does AMBASSADOR_SINGLE_NAMESPACE expect?

[MichielDeMey]

1. It doesn't, they are mutually exclusive. When only 1 namespace is required, there is no need to set an identifier. (See https://www.getambassador.io/reference/running#multiple-ambassadors-in-one-cluster)
2. The value does not matter, the code only checks the existence of the environment variable.
   The example simply sets it to "YES", cfr. https://github.com/datawire/ambassador/blob/69f224a7988b89becb13ecbc31fdf41af438a3e9/end-to-end/fixes/single-namespace.yfix#L4-L5

[MichielDeMey]

@kflynn I took a stab at it in #657

[kflynn]

I believe that this is definitely handled by the chart in helm/stable. Thanks!