Pre-seed JVB user password using debconf

After reading the Scalable setup guide and there seems to be an omission around ensuring the jvb user’s password is shared between machines - I’ve tried setting

jitsi-videobridge2 jitsi-videobridge/jvbsecret password abcd1234 
jitsi-videobridge2 jitsi-videobridge/jvb-hostname string mydomain.com 

(for example) but these values seem to be blatted over during the installation. My question is, is there a reliable way to set these password values in advance using debconf, or any other tools?

Thanks in advance,

You do a clean install? Jvb was never installed on that machine?

Use jitsi-videobridge2 jitsi-videobridge/jvb-hostname string mydomain.com, but also before installing create /etc/jitsi/videobridge/config with
JVB_HOSTNAME and JVB_SECRET values.

Does that change anything?

I don’t see jvbsecret to be read from dbconf (jitsi-videobridge/postinst at c7f2b2d50f4b03da75a78f63476f39b2761d2dd5 · jitsi/jitsi-videobridge · GitHub)