fts_enforced=yes or body return NO [SERVERBUG] Internal error occurred when SEARCH

[Alessio Cecchi]

Hi,

we have some issues related to the fts_enforced option in dovecot config.

Following the table in the docs 
(https://doc.dovecot.org/settings/plugin/fts-plugin/#plugin-fts-setting-fts-enforced), 
we cannot figure out the current behavior of the flag.

In our case we have dovecot up and running, dovecot indexes updated 
using doveadm command (fts rescan/index), but solr instance offline for 
testing.

We try to search using header subject. We tried "yes" and "body" 
fts_enforced flag's options but we get in telnet session:

C: a search header subject "test"
S: a NO [SERVERBUG] Internal error occurred. Refer to server log for 
more information. [2021-04-20 15:52:57] (0.005 + 0.000 + 0.004 secs).

But dovecot-log don't include any specific error, except for a generic:

Apr 20 15:52:57 imap dovecot: imap(test at emailtest.net) 
session=<t7RIwxyaxMxbj8Qu>: Error: fts_solr: Lookup failed: 
connect(10.0.0.2:8983) failed: Connection refused

Is there any flag or method to check if a solr instance is up and 
running and, eventually, switching to the internal dovecot indexes instead ?

Using the "no" option, for enforced flag, for us is unavailable because 
the related search could be too long and we could have timeout waiting 
the results.

We aim to achieve the following result: if our solr instance is 
unavailable, we should switch the imap searches from full-text to 
headers only.

Could you suggest something in this direction? We running doveoct 2.3.14.

Thanks

-- 
Alessio Cecchi
Postmaster @ http://www.qboxmail.it
https://www.linkedin.com/in/alessice