[Dovecot] How to upgrade a running Dovecot?

[Mike Brudenell]

Greetings -

Could someone confirm how to perform various upgrades on a live  
system running Dovecot please?


Scenario 1:  Change to dovecot.conf
===================================
If I make a change to dovecot.conf am I right in thinking I can  
simply send a HUP signal to the main dovecot process to get it to re- 
read the configuration file and act on its revised content?


Scenario 2:  Altered SSL Certificates
=====================================
I need to replace our current certificates and have prepared new  
files containing the replacement certificate and private key.  Am I  
right in thinking that I can simply modify dovecot.conf to point at  
the new files and send a HUP signal to dovecot?  Specifically, will  
new connections use the revised certificates, and existing  
connections continue to work OK without interruption?


Scenario 3:  Software Upgrade
=============================
I build a particular version of Dovecot into the tree /usr/local/ 
dovecot-A.B.C and then have a symlink called "dovecot" pointing at  
the this directory.  To upgrade I can then build the new version  
into /usr/local/dovecot-X.Y.Z and test.

To actually switch over the live service to the new X.Y.Z version do  
I need to:

   a) Totally shut down the old A.B.C version of Dovecot, thereby  
breaking all
      open connections for users?  or

   b) Assuming I am using "shutdown_clients = no" can I just kill the  
master
      "dovecot" process and then start up the new version?

Ideally I want existing connections to remain running, but new  
connections to start up using the new X.Y.Z version of Dovecot.

The comment for "shutdown_clients" implies this, but also says:

     "This however means that after master process has died, the client
     processes can't write to log files anymore."

So if I understand this correctly then with "shutdown_clients = no"  
in force then the sequence and behaviour is this? ...

     1.  Old version A.B.C of Dovecot running, clients can log  
through the
         master "dovecot" process to the logfiles.

     2.  Kill the old master "dovecot" process, start new X.Y.Z  
version up.

     3.  New connections get served by version X.Y.Z.
         Old connections DON'T get killed and can continue, BUT can  
no longer
         write anything to the logfiles?


With many thanks,
Mike B-)

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