If you're asking how to configure bip to use the Let's Encrypt certificate so that clients can connect to it via SSL, the documentation provides the following:
client_side_ssl (default: false)
When true, clients will need to connect to BIP using SSL. You'll also need to
generate a SSL cert/key pair in <bipdir>/bip.pem (usually ~/.bip/bip.pem or
/var/lib/bip/bip.pem) or <client_side_ssl_pem> if defined.
client_side_ssl_pem (default: <bipdir>/bip.pem)
Set this to the full path of the cert/key pair bip should use to accept clients
SSL connections
So from that I gather you will need to cat privkey.pem cert.pem > bip.pem
and enable client_side_ssl
and point client_side_ssl_pem
to bip.pem
if it's not in one of the specified locations.
I don't believe you'll need to add the CA chain as Let's Encrypt is a trusted CA and the clients should be able to reconstruct the chain themselves. If that's not the case, you can add chain.pem
to bip.pem
as well.
I also found a handy guide that might be of use here: https://flexion.org/posts/2014-04-bip-irc-proxy/