[Kea-users] migrating from DHCPd to Kea

Mon Oct 28 09:09:49 UTC 2024

Hi Brendan,

There may be some small differences between MariaDB and MySQL, but
from the perspective of configuring Kea, there is only one choice:
MySQL which supports both.

The error that you opened this email thread with: "reason: Lost
connection to server during query (error code: 2013)." indicates that
Kea is getting disconnected from the database server.  Suggest you
look at the parameters:

- on-fail -> stop-retry-exit  (This is probably the default)
- reconnect-wait-time
- max-reconnect-tries

These are described here:
https://kea.readthedocs.io/en/kea-2.6.1/arm/database-connectivity.html
and here: https://kea.readthedocs.io/en/kea-2.6.1/arm/dhcp4-srv.html#database-configuration4

By default Kea will just exit without trying to reconnect, I believe.

Thank you,
Darren Ankney

On Fri, Oct 25, 2024 at 7:56 AM Brendan Kearney <bpk678 at gmail.com> wrote:
>
> On 10/25/24 6:28 AM, Darren Ankney wrote:
> > Hi Brendan,
> >
> > The ? are due to mysql prepared statements.  See here:
> > https://dev.mysql.com/doc/refman/8.4/en/sql-prepared-statements.html
> >
> > On Tue, Oct 22, 2024 at 1:59 PM Brendan Kearney <bpk678 at gmail.com> wrote:
> >> On 4/17/24 5:49 AM, Peter Davies wrote:
> >>
> >> Hi Brendan,
> >>     It is not possible to see any details from this logging.
> >>
> >> You should check your haproxy configuration, Kea cannot continue processing
> >> requests if it is unable to connect to the lease database.
> >>
> >> I suggest that you temporarily enable Severity DEBUG and debuglevel 99 so you
> >> can see requests and how Kea is processing them.
> >>
> >>   As all your reservations are global, you should define
> >>   "reservations-global": true,"
> >>   the default is false.
> >>
> >>   All pools are guarded by client classes. The client may not be associated with
> >>   any of these classes.
> >>
> >> /Peter
> >>
> >>
> >> digging back into the database issue, i found the following messages in "journactl -lu kea-dhcp4":
> >>
> >> Oct 15 20:34:43 server1 systemd[1]: Started kea-dhcp4.service - Kea DHCPv4 Server.
> >> Oct 15 20:34:43 server1 kea-dhcp4[1930]: 2024-10-15 20:34:43.848 INFO  [kea-dhcp4.dhcp4/1930.140675063382400] DHCP4_STARTING Kea DHCPv4 server version 2.4.0 (stable) starting
> >> Oct 16 03:24:44 server1 kea-dhcp4[1930]: 2024-10-16 03:24:44.303 ERROR [kea-dhcp4.database/1930.140675063382400] DATABASE_MYSQL_FATAL_ERROR Unrecoverable MySQL error occurred: unable to execute for <SELECT  a.id,  a.object_type,  a.object_id,  a.modification_type,  r.modification_ts,  r.id,   r.log_message FROM dhcp4_audit AS a INNER JOIN dhcp4_audit_revision AS r   ON a.revision_id = r.id INNER JOIN dhcp4_server AS s  ON r.server_id = s.id WHERE (s.tag = ? OR s.id = 1) AND ((r.modification_ts, r.id) > (?, ?)) ORDER BY r.modification_ts, r.id>, reason: Lost connection to server during query (error code: 2013).
> >> Oct 16 03:24:44 server1 kea-dhcp4[1930]: 2024-10-16 03:24:44.303 ERROR [kea-dhcp4.dhcp4/1930.140675063382400] DHCP4_CB_PERIODIC_FETCH_UPDATES_FAIL error on periodic attempt to fetch configuration updates from the configuration backend(s): fatal database error or connectivity lost
> >> Oct 16 03:24:44 server1 systemd[1]: kea-dhcp4.service: Main process exited, code=exited, status=1/FAILURE
> >> Oct 16 03:24:44 server1 systemd[1]: kea-dhcp4.service: Failed with result 'exit-code'.
> >> Oct 16 03:24:44 server1 systemd[1]: kea-dhcp4.service: Consumed 14.206s CPU time.
> >>
> >> there is a select statement in the logs that failed and killed the instance.  i took the select statement in the logs and ran it in a mariadb client, phpMyAdmin.  when i submitted the query, i got the following error info back:
> >>
> >> Error
> >>
> >> Static analysis:
> >>
> >> 3 errors were found during analysis.
> >>
> >>      Variable name was expected. (near "?" at position 261)
> >>      Variable name was expected. (near "?" at position 310)
> >>      Variable name was expected. (near "?" at position 313)
> >>
> >> SQL query: Copy Documentation
> >>
> >> SELECT a.id, a.object_type, a.object_id, a.modification_type, r.modification_ts, r.id, r.log_message FROM dhcp4_audit AS a INNER JOIN dhcp4_audit_revision AS r ON a.revision_id = r.id INNER JOIN dhcp4_server AS s ON r.server_id = s.id WHERE (s.tag = ? OR s.id = 1) AND ((r.modification_ts, r.id) > (?, ?)) ORDER BY r.modification_ts, r.id LIMIT 0, 25
> >>
> >> MySQL said: Documentation
> >> #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '? OR s.id = 1) AND ((r.modification_ts, r.id) > (?, ?)) ORDER BY r.modificati...' at line 1
> >>
> >> the problem is not my database or connectivity to it.  the issues is a malformed query, that uses question marks ( ? ) which seem to be invalid characters.  i logged into the database using the mysql command line client and issued the same query, to be sure the error was not related to something in phpMyAdmin, and i got the following error info back:
> >>
> >> MariaDB [kea]> SELECT  a.id,  a.object_type,  a.object_id,  a.modification_type,  r.modification_ts,  r.id,   r.log_message FROM dhcp4_audit AS a INNER JOIN dhcp4_audit_revision AS r   ON a.revision_id = r.id INNER JOIN dhcp4_server AS s  ON r.server_id = s.id WHERE (s.tag = ? OR s.id = 1) AND ((r.modification_ts, r.id) > (?, ?)) ORDER BY r.modification_ts, r.id;
> >> ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '? OR s.id = 1) AND ((r.modification_ts, r.id) > (?, ?)) ORDER BY r.modificati...' at line 1
> >>
> >> from the looks of things, there is a malformed query and the error causes the kea instance to fail.  is there a "dialect" issue with the way the db query is formulated/constructed in kea for mariadb vs postgresql?  i dont have a postgresql instance handy to test against.  given the ERROR, not WARNING, status of the log message, i would assume that the malformed query causes the resulting failure of the instance because kea cannot continue.  how do i figure a way past these errors?
> >>
> >> thanks,
> >>
> >> brendan
> >>
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>
> since i am using MariaDB, does that make a difference?  MariaDB does
> have a prepared statement capability, but are there differences between
> MySQL and MariaDB? https://mariadb.com/kb/en/prepared-statements/
> clearly, there is something askew... are there "dialects" for MySQL and
> MariaDB, where i should be specifying MariaDB, instead of MySQL?
>
> thanks,
>
> brendan
>
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