Deploy container app with a custom domain

[smirkingsquiggly]

I'd like to deploy a container app with Aspire and setup a custom domain for it.
I have a working GitHub Actions workflow.
I've setup the custom domain for the container app manually in the Azure portal with a managed certificate and that works.

Now I want to include the custom domain in the deployment.
I ran azd infra gen.
In the `myapp.tmpl.yaml' file, I put this ingress:

ingress:
  external: true
  targetPort: {{ targetPortOrDefault 8080 }}
  transport: http
  allowInsecure: false
  customDomains:
    - name: myawesomedomain.com
      bindingType: SniEnabled

When I deploy, I get this error:

RESPONSE 400: 400 Bad Request
ERROR CODE: CertificateMissing
--------------------------------------------------------------------------------
{
  "error": {
    "code": "CertificateMissing",
    "message": "CertificateId property is missing for customDomain 'myawesomedomain.com'."
  }
}
--------------------------------------------------------------------------------

How do I fix this?

[smirkingsquiggly]

Nvm, I had to reference the certificate which is registered in my Container Apps Environment.

ingress:
  external: true
  targetPort: {{ targetPortOrDefault 8080 }}
  transport: http
  allowInsecure: false
  customDomains:
    - name: myawesomedomain.com
      bindingType: SniEnabled
      certificateId: {{ .Env.AZURE_MANAGED_CERTIFICATE_ID }}

Then, I added a secret AZURE_MANAGED_CERTIFICATE_ID (which holds the resource id of the certificate) to GitHub and voila.

[davidfowl]

One downside of doing it this way is that any changes you make to the app host won't be reflected here and it'll be wiped out when you run azd infra gen again.

dotnet/docs-aspire#2623

@IEvangelist @mitchdenny we really need an end to end doc on using custom domains with aspire + aca

[mitchdenny]

@davidfowl spent a bunch of time this weekend doing a deep dive into this. The process is as described in the XML doc comments for the method but obviously we can make that nicer with a more elaborate doc with graphics etc.

But I also went a bit further to see what the grow-up plan looks like when you want to go from one environment to two and beyond and I hit a few snags. I started this PR to see if I can come up with a viable work around for it:

Azure/azure-dev#5596

Not much we can do about making it a multi-step process though unfortunately :(

[davidfowl]

We need to just out it in the docs. Nobody will read that long doc comment 😅