Dear Ian,

Thank you for being so quick to respond.
I have run a rs.status() and rs.slaveOk() command on the mongo replica set.
Everything looks in order.

I have also run a query on the Primary for the settings on the app (also attached). I can see that the database record for the application seem to have been update on the mongo, yet the #next record never progresses. The command lines keeps on accepting new values but only returns the original one.


-----Original Message-----
From: <email address hidden> <email address hidden> On Behalf Of Ian Booth
Sent: 19 April 2019 11:38
To: Guitton, Florian L P <email address hidden>
Subject: [Bug 1825500] Re: [2.6-beta1] Configuration changes do not propagate correctly with HA enabled

Just a note - the config checksums are used to prevent unnecessary firing of the config-changed hook on units. The fact that the bug report seems to say that the config-change hooks are correctly firing each time a config change is made suggests that the change is correctly being stored and propagated to the unit agents. The config checksum is only used on the unit agents, not elsewhere.

Perhaps there's a mongo replication issue. It could be that the config change is being written to the primary, but the secondaries are stale. I can't recall off hand if read operations are allowed to be done on secondaries. You could open a mongo client session on the primary and check the db content directly to ensure the updated config is being written. Or you could run rs.status() in the mongo shell to see that everything is healthy.

Regardless, we'll try and reproduce.


** Changed in: juju
    Milestone: None => 2.6-rc1

** Changed in: juju
   Importance: Undecided => High

** Changed in: juju
       Status: New => Triaged

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https://bugs.launchpad.net/bugs/1825500

Title:
  [2.6-beta1] Configuration changes do not propagate correctly with HA
  enabled

Status in juju:
  Triaged

Bug description:
  Hello everyone !

  I hope this Easter period treats you well.
  I was testing the new capabilities of cross-cloud controllers in Juju 2.6-beta1 when I realised configuration changes are only propagated at times or seemingly not committed to database.
  I am aware of the checksuming changes that were brought in recently, but it seems to be very inconsistent.

  I have a Juju controller deployed on MAAS with HA enabled, 3 nodes.
  All three controllers do not report any error in their logs. When I change the configuration of an application the config-updates triggers on the agents, but no commit is made to the database.
  When I try to make the changes multiple times in a row, it will accept the input every time, proceed to triggering the config-update hook on all agent every time, but will indeed not propagate the new values nor commit them. Illustrated by the following:

  root@:~# juju config percona-cluster os-access-hostname
  foo.example.com
  root@:~# juju config percona-cluster os-access-hostname=foo.example.com
  WARNING the configuration setting "os-access-hostname" already has the value "foo.example.com"
  root@:~# juju config percona-cluster os-access-hostname=bar.example.com
  root@:~# juju config percona-cluster os-access-hostname
  foo.example.com
  root@:~# juju config percona-cluster os-access-hostname=bar.example.com
  root@:~# juju config percona-cluster os-access-hostname=bar.example.com
  root@:~# juju config percona-cluster os-access-hostname=bar.example.com
  root@:~# juju config percona-cluster os-access-hostname
  foo.example.com

  I am happy to send anything that might be of use, just let me know.
  Thank you very much for your support.

  Best wishes,

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