Registering multiple hostnames fails because of newline character

[wandb-zacharyblasczyk]

What happened:

I have created an ingress with the following annotations to be able to access my k8s service via ALB from multiple hostnames.

apiVersion: v1
items:
- apiVersion: networking.k8s.io/v1
  kind: Ingress
  metadata:
    annotations:
      alb.ingress.kubernetes.io/certificate-arn: arn:aws:acm:us-east-2:..../a08f50c0-3a50-4dde-bd7f-676060c01e5e
      alb.ingress.kubernetes.io/inbound-cidrs: |
        0.0.0.0/0,10.0.0.0/16
      alb.ingress.kubernetes.io/listen-ports: '[{"HTTPS": 443}]'
      alb.ingress.kubernetes.io/load-balancer-name: example-alb-k8s
      alb.ingress.kubernetes.io/scheme: internet-facing
      alb.ingress.kubernetes.io/target-type: ip
      external-dns.alpha.kubernetes.io/hostname: |
        subdomain-a.hostedzone.com,subdomain-b.hostedzone.com
      external-dns.alpha.kubernetes.io/ingress-hostname-source: annotation-only

Debug logs indicate an erroneous newline character \n in the DNS record for subdomain-b.hostedzone.com:

time="..." level=debug 
msg="Endpoints generated from ingress: default/example: 
[subdomain-a.hostedzone.com 0 IN CNAME  ${ALB_DNS} [] subdomain-b.hostedzone.com/n 0 IN CNAME  ${ALB_DNS} []]"

What you expected to happen:

I expected external DNS to create two sets of records, one for each of the following:

• subdomain-a.hostedzone.com
• subdomain-b.hostedzone.com

Ideally, whitespace should be handled similarly to how the AWS Load Balancer does for the alb.ingress.kubernetes.io/inbound-cidrs.

How to reproduce it (as minimally and precisely as possible):

Annotate your ingress with both of these:

external-dns.alpha.kubernetes.io/hostname: |
  subdomain-a.hostedzone.com,subdomain-b.hostedzone.com
external-dns.alpha.kubernetes.io/ingress-hostname-source: annotation-only

Environment:

• External-DNS version (use external-dns --version): registry.k8s.io/external-dns/external-dns:v0.14.0
• DNS provider: Route53