if you need to force the renewal of your certificates with cert-manager (under kubernetes), (possibly due to the 2020.02.29 CAA Rechecking Bug ), then you can delete the certificate in your kubernetes cluster and cert-manager will get a new one (tested with cert-manager 0.9.1).
The certificate will be in a kubernetes
secret. Take care not to remove the wrong secret: there can be multiple
secrets of the same name in different namespaces! Before deleting the secret you can have a look at it with
kubectl get secret name_of_your_secret -o yaml. It should have an entry named
tls.crt which is the certificate that was issued to you by letsencrypt.
If someone could report here on how one can display/decode the cert contained in the value of the
tls.crt key, that would be extra useful!