This question is a follow up to Unable to configure Google Cloud Pub/Sub push subscriber
As per the answer, self-signed certificates are not supported when using a push subscriber. Are certificates generated via letsencrypt client supported ? Is it recommended to use letsencrypt ?
Yes. Sorry it took a long time, but I have verified that letsencrypt certs are working fine for this purpose.
来源：https://stackoverflow.com/questions/33790132/does-google-cloud-pub-sub-support-letsencrypt-certificates