Migrate dev-proxy-vmss to Azure Linux and enable rolling OS update

[nwnt]

Which issue this PR addresses:

Fixes: ARO-7329

What this PR does / why we need it:

Security Sprint/Waves requires that 1p apps start using Azure Linux as its base OS and enable VMSS auto image upgrade.

To enable VMSS rolling upgrades, we need an LB with a healthcheck. Dev proxy doesn't have a healthcheck endpoint so I added a simple one on port 8080.

Test plan for issue:

Ensure the deployment is done and e2e runs successfully in INT. The changes will not be applied to Prod.

Is there any documentation that needs to be updated for this PR?

No

How do you know this will function as expected in production?

N/A

[nwnt]

/azp run e2e

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mociarain]

In principle I think this makes sense but I have some questions:

• What do we do in prod and why do we need a dev-proxy?
• Should docs be updated as part of this?
• As far as I can make out, this code is used in quite a narrow set of places and I'm not even sure we use those any more. Possibly this can all be gutted?

[s-fairchild]

In principle I think this makes sense but I have some questions:

* What do we do in prod and why do we need a dev-proxy?

* Should docs be updated as part of this?

* As far as I can make out this code is in a quite narrow set of places and I'm not even sure we use those anymore. Possibly this can all be gutted?

@mociarain Here's it's purpose, from the ARO Wiki. Shared environment for local RP development

dev-proxy-vmss - This is needed as a proxy for your local PR to access the k8s control plane endpoints while the cluster is being provisioned.

I agree, more documentation on this VMSS would be nice.

[nwnt]

@mociarain production is not needed as this is used in dev/INT only. dev-proxy-vmss can't be gutted yet mainly because it's still being used by non-prod environments, especially CI-e2e.

to be honest, I'm not an expert about this component myself.... not sure if I'm the right person to write the doc for it. Can we track doc improvement in a separate ticket instead?

[hlipsig]

/azp run e2e

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[kimorris27]

LGTM as long as E2E passes 👍🏻

[kimorris27]

@nwnt @mociarain , I think the proxy VMSS is sufficiently covered in documentation already. See here: https://msazure.visualstudio.com/AzureRedHatOpenShift/_wiki/wikis/ARO.wiki/166757/Debug-E2E

I also added a link to this "Debug-E2E" page on the one that @s-fairchild linked to.

[hlipsig]

I'm still just waiting for CI to report successful. It's okay to merge whenever that happens.

[hlipsig]

/azp run ci

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).