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Posted to dev@httpd.apache.org by Mike Rumph <mi...@oracle.com> on 2014/03/27 21:16:55 UTC
Configuration error handling after httpd restart
Hello all,
I have been doing some testing on the results of httpd restart with
configuration errors.
This gave me some interesting results.
For these tests I build httpd trunk with APR trunk on Linux using the
following configure:
$ ./configure --prefix=/home/mrumph/apache25 --with-included-apr
--with-mpm=worker --enable-mpms-shared='worker'
Modify the default httpd.conf to include the following line:
Listen localhost:8080
Start the httpd server and verify the process information.
$ bin/apachectl -k start
$ ps -ef | grep -i httpd
Now restart httpd from this starting point with the following
configuration error cases:
Case 1: An unknown directive.
Add the following line to the httpd.conf file.
Xyzzy
bin/apachectl -k restart
- Returns with exit code 1 and following error message in stderr:
AH00526: Syntax error on line 198 of /home/mrumph/apache25/conf/httpd.conf:
Invalid command 'Xyzzy', perhaps misspelled or defined by a module not
included in the server configuration
httpd: abnormal exit 1
$ ps -ef | grep -i httpd
- The httpd server was not stopped and all of the previous processes
remain.
- And the logs/httpd.pid file remains intact.
$ tail logs/error_log
- No error message logged.
Case 2: A duplicate Listen directive.
Duplicate the Listen directive in the httpd.conf file.
Listen localhost:8080
Listen localhost:8080
$ bin/apachectl -k restart
- Returns with exit code 0 and no error message in stderr.
- So the httpd server appears to be working at this point.
- (But appearances are deceiving.)
$ ps -ef | grep -i httpd
- All of the httpd processes have stopped.
- But the logs/httpd.pid file remains intact.
$ tail logs/error_log
[Thu Mar 27 11:26:22.836887 2014] [mpm_worker:notice] [pid 2677:tid
47577479346656] AH00298: SIGHUP received. Attempting to restart
(98)Address already in use: AH00072: make_sock: could not bind to
address 127.0.0.1:8080
[Thu Mar 27 11:26:22.844003 2014] [mpm_worker:alert] [pid 2677:tid
47577479346656] no listening sockets available, shutting down
[Thu Mar 27 11:26:22.844031 2014] [core:emerg] [pid 2677:tid
47577479346656] AH00019: Unable to open logs, exiting
This was httpd trunk, but similar results are seen with httpd 2.2.22,
2.2-HEAD and 2.4.6.
Before working on this as a bug, I am trying to understand what should
be the correct behavior.
I think case 1 is working correctly.
But case 2 doesn't seem quite right.
First of all, it doesn't seem correct to have an httpd.pid file when all
of the httpd processes have vanished.
Secondly, it would be nice to see an error code from the apachectl -k
restart.
(But this is probably due to a different processing phase in the
validation for both of the cases.)
It is also a little strange to see a message "Unable to open logs" in
the log.
Does anyone have some opinions what the correct behavior should be for
these cases.
If there are some actual bugs here, I have some time available to work
on them.
Thanks,
Mike Rumph
Re: Configuration error handling after httpd restart
Posted by Yehuda Katz <ye...@ymkatz.net>.
Since this is up for discussion anyway, what if there was an option to set
a directive as ignore-able.
For example, PHP allows you to preface a function with `@` to ignore errors
(http://www.php.net/manual/en/language.operators.errorcontrol.php).
That way, if you restart and the error is "Invalid command 'Xyzzy',", you
could make the decision to ignore it.
I am not sure how useful this would be in practice. The only thing that
comes to mind is with a module like mod_auth_mysql where you could ignore
errors about it being missing while still requiring some other type of
authentication with satisfy any.
- Y
On Mon, Apr 14, 2014 at 12:00 PM, Jim Riggs <ap...@riggs.me> wrote:
> On 14 Apr 2014, at 10:38, Eric Covener <co...@gmail.com> wrote:
>
> > On Mon, Apr 14, 2014 at 11:15 AM, Mike Rumph <mi...@oracle.com>
> wrote:
> >> If there is an unknown directive in the config file, simply ignore it
> with a
> >> warning.
> >
> > You can't do that. What if it was "Reqiure"?
>
> I agree with Eric. I would not want unknown directives to be ignored. It
> might be a typo of a really important directive like Eric describes. Or,
> what if a module I really, really need is accidentally disabled and we just
> ignore all of its directives? Not good.
>
> In this particular case, duplicating a Listen directive doesn't seem like
> it should bomb out the server.
>
> Listen 80
> ...
> Listen 80
>
> It's superfluous, but not really a critical error. So, my patch just
> ignores subsequent duplicate Listens.
>
>
Re: Configuration error handling after httpd restart
Posted by Jim Riggs <ap...@riggs.me>.
On 14 Apr 2014, at 10:38, Eric Covener <co...@gmail.com> wrote:
> On Mon, Apr 14, 2014 at 11:15 AM, Mike Rumph <mi...@oracle.com> wrote:
>> If there is an unknown directive in the config file, simply ignore it with a
>> warning.
>
> You can't do that. What if it was "Reqiure"?
I agree with Eric. I would not want unknown directives to be ignored. It might be a typo of a really important directive like Eric describes. Or, what if a module I really, really need is accidentally disabled and we just ignore all of its directives? Not good.
In this particular case, duplicating a Listen directive doesn't seem like it should bomb out the server.
Listen 80
...
Listen 80
It's superfluous, but not really a critical error. So, my patch just ignores subsequent duplicate Listens.
Re: Configuration error handling after httpd restart
Posted by Eric Covener <co...@gmail.com>.
On Mon, Apr 14, 2014 at 11:15 AM, Mike Rumph <mi...@oracle.com> wrote:
> If there is an unknown directive in the config file, simply ignore it with a
> warning.
You can't do that. What if it was "Reqiure"?
Re: Configuration error handling after httpd restart
Posted by Mike Rumph <mi...@oracle.com>.
Hello Jim,
Thanks for taking a look at this and providing a patch for case 2
(duplicate Listen directives).
I will need to evaluate this patch in more detail.
Your approach of simply ignoring duplicate Listen directives with a
warning seems reasonable.
At least in the simple case that I listed.
But it does cause a change in behavior for "apachectl -k start" as well
as "apachectl -k restart".
Is this acceptable?
The same approach could be taken for case 1.
If there is an unknown directive in the config file, simply ignore it
with a warning.
Does anyone else have an opinion on this?
There are also underlying issues that are bypassed by your fix.
Other more complicated test cases may uncover these again.
I hope to have some time to investigate these issues and do further
negative testing.
Thanks,
Mike
On 4/11/2014 10:43 AM, Jim Riggs wrote:
> On 27 Mar 2014, at 14:16, Mike Rumph <mi...@oracle.com> wrote:
>
>> Hello all,
>>
>> I have been doing some testing on the results of httpd restart with configuration errors.
>> This gave me some interesting results.
>>
>> For these tests I build httpd trunk with APR trunk on Linux using the following configure:
>> $ ./configure --prefix=/home/mrumph/apache25 --with-included-apr --with-mpm=worker --enable-mpms-shared='worker'
>>
>> Modify the default httpd.conf to include the following line:
>> Listen localhost:8080
>>
>> Start the httpd server and verify the process information.
>> $ bin/apachectl -k start
>> $ ps -ef | grep -i httpd
>>
>> Now restart httpd from this starting point with the following configuration error cases:
>>
>> Case 1: An unknown directive.
>> Add the following line to the httpd.conf file.
>> Xyzzy
>>
>> bin/apachectl -k restart
>> - Returns with exit code 1 and following error message in stderr:
>> AH00526: Syntax error on line 198 of /home/mrumph/apache25/conf/httpd.conf:
>> Invalid command 'Xyzzy', perhaps misspelled or defined by a module not included in the server configuration
>> httpd: abnormal exit 1
>>
>> $ ps -ef | grep -i httpd
>> - The httpd server was not stopped and all of the previous processes remain.
>> - And the logs/httpd.pid file remains intact.
>>
>> $ tail logs/error_log
>> - No error message logged.
>>
>> Case 2: A duplicate Listen directive.
>> Duplicate the Listen directive in the httpd.conf file.
>> Listen localhost:8080
>> Listen localhost:8080
>>
>> $ bin/apachectl -k restart
>> - Returns with exit code 0 and no error message in stderr.
>> - So the httpd server appears to be working at this point.
>> - (But appearances are deceiving.)
>>
>> $ ps -ef | grep -i httpd
>> - All of the httpd processes have stopped.
>> - But the logs/httpd.pid file remains intact.
>>
>> $ tail logs/error_log
>> [Thu Mar 27 11:26:22.836887 2014] [mpm_worker:notice] [pid 2677:tid 47577479346656] AH00298: SIGHUP received. Attempting to restart
>> (98)Address already in use: AH00072: make_sock: could not bind to address 127.0.0.1:8080
>> [Thu Mar 27 11:26:22.844003 2014] [mpm_worker:alert] [pid 2677:tid 47577479346656] no listening sockets available, shutting down
>> [Thu Mar 27 11:26:22.844031 2014] [core:emerg] [pid 2677:tid 47577479346656] AH00019: Unable to open logs, exiting
>>
>>
>> This was httpd trunk, but similar results are seen with httpd 2.2.22, 2.2-HEAD and 2.4.6.
>>
>>
>> Before working on this as a bug, I am trying to understand what should be the correct behavior.
>> I think case 1 is working correctly.
>> But case 2 doesn't seem quite right.
>> First of all, it doesn't seem correct to have an httpd.pid file when all of the httpd processes have vanished.
>> Secondly, it would be nice to see an error code from the apachectl -k restart.
>> (But this is probably due to a different processing phase in the validation for both of the cases.)
>> It is also a little strange to see a message "Unable to open logs" in the log.
>>
>> Does anyone have some opinions what the correct behavior should be for these cases.
>>
>> If there are some actual bugs here, I have some time available to work on them.
>
>
> Check out the attached patch to ignore duplicate Listen directives.
>
>
>
>
Re: Configuration error handling after httpd restart
Posted by Jim Riggs <ap...@riggs.me>.
On 27 Mar 2014, at 14:16, Mike Rumph <mi...@oracle.com> wrote:
> Hello all,
>
> I have been doing some testing on the results of httpd restart with configuration errors.
> This gave me some interesting results.
>
> For these tests I build httpd trunk with APR trunk on Linux using the following configure:
> $ ./configure --prefix=/home/mrumph/apache25 --with-included-apr --with-mpm=worker --enable-mpms-shared='worker'
>
> Modify the default httpd.conf to include the following line:
> Listen localhost:8080
>
> Start the httpd server and verify the process information.
> $ bin/apachectl -k start
> $ ps -ef | grep -i httpd
>
> Now restart httpd from this starting point with the following configuration error cases:
>
> Case 1: An unknown directive.
> Add the following line to the httpd.conf file.
> Xyzzy
>
> bin/apachectl -k restart
> - Returns with exit code 1 and following error message in stderr:
> AH00526: Syntax error on line 198 of /home/mrumph/apache25/conf/httpd.conf:
> Invalid command 'Xyzzy', perhaps misspelled or defined by a module not included in the server configuration
> httpd: abnormal exit 1
>
> $ ps -ef | grep -i httpd
> - The httpd server was not stopped and all of the previous processes remain.
> - And the logs/httpd.pid file remains intact.
>
> $ tail logs/error_log
> - No error message logged.
>
> Case 2: A duplicate Listen directive.
> Duplicate the Listen directive in the httpd.conf file.
> Listen localhost:8080
> Listen localhost:8080
>
> $ bin/apachectl -k restart
> - Returns with exit code 0 and no error message in stderr.
> - So the httpd server appears to be working at this point.
> - (But appearances are deceiving.)
>
> $ ps -ef | grep -i httpd
> - All of the httpd processes have stopped.
> - But the logs/httpd.pid file remains intact.
>
> $ tail logs/error_log
> [Thu Mar 27 11:26:22.836887 2014] [mpm_worker:notice] [pid 2677:tid 47577479346656] AH00298: SIGHUP received. Attempting to restart
> (98)Address already in use: AH00072: make_sock: could not bind to address 127.0.0.1:8080
> [Thu Mar 27 11:26:22.844003 2014] [mpm_worker:alert] [pid 2677:tid 47577479346656] no listening sockets available, shutting down
> [Thu Mar 27 11:26:22.844031 2014] [core:emerg] [pid 2677:tid 47577479346656] AH00019: Unable to open logs, exiting
>
>
> This was httpd trunk, but similar results are seen with httpd 2.2.22, 2.2-HEAD and 2.4.6.
>
>
> Before working on this as a bug, I am trying to understand what should be the correct behavior.
> I think case 1 is working correctly.
> But case 2 doesn't seem quite right.
> First of all, it doesn't seem correct to have an httpd.pid file when all of the httpd processes have vanished.
> Secondly, it would be nice to see an error code from the apachectl -k restart.
> (But this is probably due to a different processing phase in the validation for both of the cases.)
> It is also a little strange to see a message "Unable to open logs" in the log.
>
> Does anyone have some opinions what the correct behavior should be for these cases.
>
> If there are some actual bugs here, I have some time available to work on them.
Check out the attached patch to ignore duplicate Listen directives.
Re: Configuration error handling after httpd restart
Posted by Eric Covener <co...@gmail.com>.
On Thu, Mar 27, 2014 at 4:16 PM, Mike Rumph <mi...@oracle.com> wrote:
> - And the logs/httpd.pid file remains intact.
I noticed this once, IIRC if the 2nd pass of post-config returns an
error, the pidfile is not cleaned up. Modules like to cheat and only
do their work in the 2nd pass.
--
Eric Covener
covener@gmail.com