Use Helm for installing AES

[inercia]

Description

Use the Helm repo for running edgectl install

Related Issues

#2466

Testing

1 - Basic installation

• install with edgectl install
• After a successful installation, check that the Helm release is there:

$ helm list -n ambassador 
NAME      	NAMESPACE 	REVISION	UPDATED                                 	STATUS  	CHART           	APP VERSION
ambassador	ambassador	1       	2020-04-08 14:03:12.893838399 +0200 CEST	deployed	ambassador-6.2.4	1.3.2      

• Check that the app.kubernetes.io/managed-by label is properly set:

$ kubectl get deployments -n ambassador ambassador -o yaml | grep managed-by
    app.kubernetes.io/managed-by: edgectl
        app.kubernetes.io/managed-by: edgectl

2 - Installation after Helm

• Install AES with Helm. For example (in local env, with NodePort) with :

$ kubectl create namespace ambassador
namespace/ambassador created
$ helm install ambassador --namespace ambassador datawire/ambassador --set service.type=NodePort --wait
# ...

• Check that edgectl install detects the Helm installation and continues with the rest of the setup:

 $ ./edgectl install                

Installing the Ambassador Edge Stack

Please enter an email address for us to notify you before your TLS certificate
and domain name expire. In order to acquire the TLS certificate, we share this
email with Let’s Encrypt.
Email address [alvaro.saurin@*******]: 

========================================================================
Beginning Ambassador Edge Stack Installation

-> Checking latest version of Ambassador Edge Stack available...
-> Found an existing installation of Ambassador Edge Stack 1.3.2 [helm].
-> Ambassador was installed with Helm: will continue setup...
-> Checking the AES pod deployment
...

3 - Installation after an old Helm chart

• Same as previous scenario. Check that edgectl install aborts with a message saying it does not support upgrades.

4 - Installation after applying manifests from https://www.getambassador.io/yaml/*.yaml

• Same as previous scenario. Check that edgectl install aborts with a message saying it does not support upgrades.

[ark3]

Looks good overall, but we need to be careful with a few details.

Alread addressed comments. Thanks!

[alexgervais]

Just a small change and some questions:

• Can (and where) we set the app.kubernetes.io/managed-by=edgectl label for each install?
• There are a few newly introduced or leftover TODOs. Do we want to address them in this PR?

[khussey]

@inercia it seems to me that we should be adding new "help" pages in conjunction with these changes, to cover the new Helm-specific failure cases. These cases should have new documentation URLs assigned to them (rather than repurposing existing ones), so that users who have downloaded the existing non-Helm installer can still find help for the obsolete failure cases.

We'll also need to think about the best way to deprecate the obsolete help pages that no longer apply (perhaps by adding a message at the top of them indicating that a newer version of the installer is available and that they should download it for an improved experience)...

Please coordinate with @brucehorn and @ark3 on this to account for the changes they are making to the error messages and documentation pages.

Already addressed comments.

[khussey]

@inercia please see comments, thanks.

I think I have addressed all the comments...