Modifying data files while named is reloading

Thu Oct 18 16:57:17 UTC 2018

On Thu, Oct 18, 2018 at 9:01 AM Laurent Weislo <laurent.weislo at gmail.com>
wrote:

> Hi,
>
> We had a strange behaviour with our old master running bind version: 9.3.6
> release: 20.P1.el5.
>
> We modify NSC m4 data files when adding one or more A records and use the
> make command to build the full environment on the master itself. At the end
> of the build, an HUP signal is sent to the named process. After the signal
> is sent, if a new change comes in, the process occurs again, thus modifying
> the files (that are supposed to be already loaded by named).
> After a bunch of years and under heavy load on the master, we lost almost
> 4K records because the domain file seems to have been loaded while being
> generated.
>
> My questions are:
> - is 'rndc reload' returning when all zone files have been reloaded or is
> it returning while the loading process is ongoing ?
>

I believe that rndc returns immediately, while the loading process is just
starting.

> - same question with sending a HUP signal ? does it behave like 'rndc
> reload' ?
>

Signals like 'HUP' always return immediately, they have no way of knowing
what the process will do with the signal, if anything.

> - how to ensure that named has loaded the files before modifying them
> again since they are at the same location ?
>

Good question.  For sure, as Anne says, you want to build temporary files
and 'move' them to the final location, so that there are never partial
files in place.

>
> The log message reports 'loading configuration', but why not
> 'configuration files loaded' ?
>

I believe that the process starts with:
18-Oct-2018 12:55:29.975 general: info: received control channel command
'reload'
18-Oct-2018 12:55:29.975 general: info: loading configuration from
'/etc/named.conf'

And ends with:
18-Oct-2018 12:55:30.358 general: notice: all zones loaded

-- 
Bob Harold

>
> Below is the event timeline, I hope it is clear enough for everyone:
>  1. Oct 16 17:24:18 SLAVE1 named[29671]: [ID 873579 daemon.info] transfer
> of 'our.domain.com/IN' from 192.168.122.100#53: Transfer completed: 10
> messages, *14890* records, 413507 bytes, 0.249 secs (1660670 bytes/sec)
>  2. (10/16/2018 17:28:57.202:1683726) : user pid=7501 uid=root
> auid=unknown(65030) msg='cmd=/sbin/service named reload (terminal=?
> res=success)'
>  3. Oct 16 17:28:57 MASTER named[3292]: loading configuration from
> '/etc/named.conf' -> 2018101639
>  4. AUTOMATION TOOL:16-10 17:28:57 newhostname 1045 Add DNS START
>  5. 2018-10-16 17:29:00 +0200 (Tue, 16 Oct 2018) | 1 line IDXXX: Add DNS
> entry newhostname with 10.10.10.10 | r20907 |
>  6. Oct 16 17:29:02 MASTER named[3292]: zone/our.domain.com:11473: file
> does not end with newline    <- NSC make is running, generating new files
> because newhostname is added to a m4 file.
>  7. Oct 16 17:29:02 MASTER named[3292]: zone our.domain.com/IN: loaded
> serial 2018101640
>  8. Oct 16 17:29:02 MASTER named[3292]: zone our.domain.com/IN: sending
> notifies (serial 2018101640)
>  9. Oct 16 17:29:19 SLAVE1 named[29671]: [ID 873579 daemon.info] transfer
> of 'our.domain.com/IN' from 192.168.122.100#53: Transfer completed: 7
> messages, *10806* records, 302763 bytes, 0.192 secs (1576890 bytes/sec)
> 10. (10/16/2018 17:34:27.798:1683828) : user pid=12079 uid=root
> auid=unknown(65030) msg='cmd=/sbin/service named reload (terminal=?
> res=success)'
> 11. Oct 16 17:34:27 MASTER named[3292]: loading configuration from
> '/etc/named.conf' -> 2018101640
> 12. AUTOMATION TOOL:16-10 17:34:28 newhostname 1045    Add DNS    SUCCESS
> 13. Oct 16 17:34:33 MASTER named[3292]: zone our.domain.com/IN: zone
> serial unchanged
> 14. Oct 16 17:34:33 MASTER named[3292]: zone our.domain.com/IN: loaded
> serial 2018101640
> 15. Oct 16 17:34:33 MASTER named[3292]: zone our.domain.com/IN: sending
> notifies (serial 2018101640)
> 16. (10/16/2018 17:39:59.934:1683878) : user pid=15753 uid=root
> auid=unknown(65030) msg='cmd=/sbin/service named reload (terminal=?
> res=success)'
> 17. Oct 16 17:40:52 SLAVE1 named[29671]: [ID 873579 daemon.info] transfer
> of 'our.domain.com/IN' from 192.168.122.100#53: Transfer completed: 10
> messages, *14893* records, 413605 bytes, 0.255 secs (1621980 bytes/sec)
>
>
> Thank you for you help and sorry to bother you with that.
>
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