Detect tag: ...-distroless

[howardjohn]

From slack:

"""
is distroless default in 1.22 ambient profile? was just on 1.21.x and minimal profile

apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  profile: ambient
  hub: gcr.io/istio-release
  tag: {{ istioVersion }}-distroless

getting image pull errors now
Back-off pulling image "gcr.io/istio-release/pilot:1.22.0-distroless-distroless"

The issue is tag: {{ istioVersion }}-distroless
This is the old way to configure the image type. Now there is variant
Ambient defaults to vartiant: distroless
So you end up with <hub>/image:<tag>-<variant>

You should do

apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  profile: ambient
  hub: gcr.io/istio-release
  tag: {{ istioVersion }}

for ambient
or if you want distroless off-ambient

apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  hub: gcr.io/istio-release
  tag: {{ istioVersion }}
  variant: distroless

Probably we should automatically detect/warn/fix this case
"""

---

We can probably detect this in istioctl and warn or automatically correct it

[nicole-lihui]

I tried to solve the problem.
and then I found that users could not use custom variant(The configuration parameters are not exposed and cannot be verified)

generate config: unknown field "variant" in v1alpha1.Values

[howardjohn]

It is values.global.variant=debug, sorry my initial example was wrong