On Sunday, we started getting some alerts relating to a failure to automatically re-issue Let’s Encrypt certificates. A quick bit of digging yielded this error:
+ Creating fullchain.pem…
+ ERROR: An error occurred while sending get-request to http://cert.int-x3.letsencrypt.org/ (Status 301)
Let’s Encrypt have started including an HTTP redirect as part of the certificate issue process and dehydrated doesn’t pass the necessary option to curl to follow the redirect. This can be fixed by patching dehydrated (and a packaged fix for Debian Stretch is now available via Debian backports), but it can also be solved with a simple config change:
echo 'CURL_OPTS="-L"' > /etc/dehydrated/conf.d/curl.sh
Naturally, customers of our managed hosting services and customers using the free HTTPS option on our hosting accounts need not worry about this issue. Our managed hosting includes monitoring all HTTPS websites for certificates nearing expiry, so we become aware of any issues well before your users do.