cert-manager.io: no certificate issued - ssl

Question

I am working on setting up an ingress-controller for my microk8s setup.
Minimal whoami-service is up and running:
microk8s kubectl describe service whoami
Name: whoami
Namespace: default
Labels: <none>
Annotations: <none>
Selector: app=whoami
Type: ClusterIP
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.152.183.112
IPs: 10.152.183.112
Port: <unset> 80/TCP
TargetPort: 80/TCP
Endpoints: 10.1.76.35:80
Session Affinity: None
Events: <none>
Response via clusterIP working:
curl 10.152.183.112:80
Hostname: whoami-84f56668f5-g2j8j
IP: 127.0.0.1
IP: ::1
IP: 10.1.76.35
IP: fe80::90cb:25ff:fe3f:2fe7
RemoteAddr: 192.168.0.100:46568
GET / HTTP/1.1
Host: 10.152.183.112
User-Agent: curl/7.68.0
Accept: */*
I have now configured a minimal ingress.yaml as follows:
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: whoami-ingress
namespace: default
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
cert-manager.io/cluster-issuer: "cert-manager"
spec:
tls:
- hosts:
- www.example-domain.com
secretName: demo-key
rules:
- host: www.example-domain.com
http:
paths:
- path: /whoami
pathType: Prefix
backend:
service:
name: whoami
port:
number: 80
ingress seems to be up and running.
Name: whoami-ingress
Namespace: default
Address: 127.0.0.1
Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>)
TLS:
demo-key terminates www.example-domain.com
Rules:
Host Path Backends
---- ---- --------
www.example-domain.com
/whoami whoami:80 (10.1.76.35:80)
Annotations: cert-manager.io/cluster-issuer: cert-manager
nginx.ingress.kubernetes.io/rewrite-target: /
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Sync 22m (x2 over 22m) nginx-ingress-controller Scheduled for sync
Normal Sync 15m nginx-ingress-controller Scheduled for sync
Pinging the domain works (so DNS-resolving seems to work).
But when checking the certificate, there aren't any.
microk8s kubectl get certificates
No resources found in default namespace.
Where did I go wrong? Shouldn't cert-manager.io take care of the certificate?
UPDATE:
It was pointed that I seem to lack a ClusterIssuer. I have now set one up according to the cert-manager-docs using ACME:
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
name: cert-manager
spec:
acme:
# You must replace this email address with your own.
# Let's Encrypt will use this to contact you about expiring
# certificates, and issues related to your account.
email: mail#domain.com
server: https://acme-staging-v02.api.letsencrypt.org/directory
privateKeySecretRef:
# Secret resource that will be used to store the account's private key.
name: demo-key
# Add a single challenge solver, HTTP01 using nginx
solvers:
- http01:
ingress:
class: nginx
But again, no luck. I can reach my cluster from outside, but only without https. Still, get certificate shows no resources found message. Certificate is classified as non trusted, issued to Kubernetes Ingress Controller Fake Certificate.