RFC: Allow 'ip' to run in daemon mode?

RFC: Allow 'ip' to run in daemon mode?

[Ben Greear]

I'm considering modifying 'ip' to be able to run in daemon
mode so that I can do lots of IP commands without having to
pay the startup cost of iproute.

The -batch option almost works, but it's hard to programatically
figure out failure codes.

I'm thinking about making these changes:

1)  Move all of the error printing code into common methods (basically,
    wrap printf).  In daemon mode this text can be sent back to the
    calling process, and in normal mode, it will be printed to stdout/stderr
    as it is currently.

2)  Remove all or most calls to 'exit' and instead return error codes
    to the calling logic.

3)  Add ability to listen on a unix socket for commands, basically treat
    them just like batch commands, one command per packet.

4)  Return well formatted error code and text response to calling process
    over the unix socket, maybe something like:

RV: [errno or equiv, zero for success]\n
CMD: [ command string this relates to ]\n
[ Optional free form text ]


Does something like this have any chance of upstream inclusion?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: RFC: Allow 'ip' to run in daemon mode?

[Simon Horman]

On Tue, Jun 29, 2010 at 08:34:41AM -0700, Ben Greear wrote:
> I'm considering modifying 'ip' to be able to run in daemon
> mode so that I can do lots of IP commands without having to
> pay the startup cost of iproute.
> 
> The -batch option almost works, but it's hard to programatically
> figure out failure codes.
> 
> I'm thinking about making these changes:
> 
> 1)  Move all of the error printing code into common methods (basically,
>    wrap printf).  In daemon mode this text can be sent back to the
>    calling process, and in normal mode, it will be printed to stdout/stderr
>    as it is currently.
> 
> 2)  Remove all or most calls to 'exit' and instead return error codes
>    to the calling logic.
> 
> 3)  Add ability to listen on a unix socket for commands, basically treat
>    them just like batch commands, one command per packet.
> 
> 4)  Return well formatted error code and text response to calling process
>    over the unix socket, maybe something like:
> 
> RV: [errno or equiv, zero for success]\n
> CMD: [ command string this relates to ]\n
> [ Optional free form text ]
> 
> 
> Does something like this have any chance of upstream inclusion?

Hi Ben,

can't you achieve as much by omitting 3) and using stdio (cleanly)?
Or in other words, fix batch mode rather than adding another mode.
Or are you worried about backwards-compatibility?

Re: RFC: Allow 'ip' to run in daemon mode?

[Ben Greear]

On 07/01/2010 12:07 AM, Simon Horman wrote:
> On Tue, Jun 29, 2010 at 08:34:41AM -0700, Ben Greear wrote:
>> I'm considering modifying 'ip' to be able to run in daemon
>> mode so that I can do lots of IP commands without having to
>> pay the startup cost of iproute.
>>
>> The -batch option almost works, but it's hard to programatically
>> figure out failure codes.
>>
>> I'm thinking about making these changes:
>>
>> 1)  Move all of the error printing code into common methods (basically,
>>     wrap printf).  In daemon mode this text can be sent back to the
>>     calling process, and in normal mode, it will be printed to stdout/stderr
>>     as it is currently.
>>
>> 2)  Remove all or most calls to 'exit' and instead return error codes
>>     to the calling logic.
>>
>> 3)  Add ability to listen on a unix socket for commands, basically treat
>>     them just like batch commands, one command per packet.
>>
>> 4)  Return well formatted error code and text response to calling process
>>     over the unix socket, maybe something like:
>>
>> RV: [errno or equiv, zero for success]\n
>> CMD: [ command string this relates to ]\n
>> [ Optional free form text ]
>>
>>
>> Does something like this have any chance of upstream inclusion?
>
> Hi Ben,
>
> can't you achieve as much by omitting 3) and using stdio (cleanly)?
> Or in other words, fix batch mode rather than adding another mode.
> Or are you worried about backwards-compatibility?

I think the most of the work will be in steps 1 and 2.  Adding a listening
socket and dealing with that is probably 50-100 lines of code.

I'd be happy to attempt steps 1, 2, and possibly 4 for standard iproute2.
If the unix socket thing still isn't wanted, it would be relatively easy for me
to carry a patch to enable it in my own code.

I think a lot of folks are scraping the output of 'ip', so backwards compat of
the error messages is a concern.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: RFC: Allow 'ip' to run in daemon mode?

[Stephen Hemminger]

On Thu, 01 Jul 2010 08:41:45 -0700
Ben Greear <greearb@candelatech.com> wrote:

> On 07/01/2010 12:07 AM, Simon Horman wrote:
> > On Tue, Jun 29, 2010 at 08:34:41AM -0700, Ben Greear wrote:
> >> I'm considering modifying 'ip' to be able to run in daemon
> >> mode so that I can do lots of IP commands without having to
> >> pay the startup cost of iproute.
> >>
> >> The -batch option almost works, but it's hard to programatically
> >> figure out failure codes.
> >>
> >> I'm thinking about making these changes:
> >>
> >> 1)  Move all of the error printing code into common methods (basically,
> >>     wrap printf).  In daemon mode this text can be sent back to the
> >>     calling process, and in normal mode, it will be printed to stdout/stderr
> >>     as it is currently.
> >>
> >> 2)  Remove all or most calls to 'exit' and instead return error codes
> >>     to the calling logic.
> >>
> >> 3)  Add ability to listen on a unix socket for commands, basically treat
> >>     them just like batch commands, one command per packet.
> >>
> >> 4)  Return well formatted error code and text response to calling process
> >>     over the unix socket, maybe something like:
> >>
> >> RV: [errno or equiv, zero for success]\n
> >> CMD: [ command string this relates to ]\n
> >> [ Optional free form text ]
> >>
> >>
> >> Does something like this have any chance of upstream inclusion?
> >
> > Hi Ben,
> >
> > can't you achieve as much by omitting 3) and using stdio (cleanly)?
> > Or in other words, fix batch mode rather than adding another mode.
> > Or are you worried about backwards-compatibility?
> 
> I think the most of the work will be in steps 1 and 2.  Adding a listening
> socket and dealing with that is probably 50-100 lines of code.
> 
> I'd be happy to attempt steps 1, 2, and possibly 4 for standard iproute2.
> If the unix socket thing still isn't wanted, it would be relatively easy for me
> to carry a patch to enable it in my own code.
> 
> I think a lot of folks are scraping the output of 'ip', so backwards compat of
> the error messages is a concern.

Use libnl and write a real service. Maybe even use json


-- 

Re: RFC: Allow 'ip' to run in daemon mode?

[Stephen Hemminger]

write a new service rather than bloating the existing code or just use netlink or libnl

Ben Greear <greearb@candelatech.com> wrote:

>I'm considering modifying 'ip' to be able to run in daemon
>mode so that I can do lots of IP commands without having to
>pay the startup cost of iproute.
>
>The -batch option almost works, but it's hard to programatically
>figure out failure codes.
>
>I'm thinking about making these changes:
>
>1)  Move all of the error printing code into common methods (basically,
>    wrap printf).  In daemon mode this text can be sent back to the
>    calling process, and in normal mode, it will be printed to stdout/stderr
>    as it is currently.
>
>2)  Remove all or most calls to 'exit' and instead return error codes
>    to the calling logic.
>
>3)  Add ability to listen on a unix socket for commands, basically treat
>    them just like batch commands, one command per packet.
>
>4)  Return well formatted error code and text response to calling process
>    over the unix socket, maybe something like:
>
>RV: [errno or equiv, zero for success]\n
>CMD: [ command string this relates to ]\n
>[ Optional free form text ]
>
>
>Does something like this have any chance of upstream inclusion?
>
>Thanks,
>Ben
>
>-- 
>Ben Greear <greearb@candelatech.com>
>Candela Technologies Inc  http://www.candelatech.com

Re: RFC: Allow 'ip' to run in daemon mode?

[Ben Greear]

On 06/30/2010 12:00 AM, Stephen Hemminger wrote:
> write a new service rather than bloating the existing code or just use netlink or libnl

I find netlink code a pain to deal with, so I'd like to leverage
existing and ongoing support in iproute.

Would you at least consider the changes in 1) and 2)
so that the new project can continue to use iproute as upstream
w/out significant merge issues?  Those changes shouldn't
significantly add to the code, I believe.

Thanks,
Ben

>
> Ben Greear<greearb@candelatech.com>  wrote:
>
>> I'm considering modifying 'ip' to be able to run in daemon
>> mode so that I can do lots of IP commands without having to
>> pay the startup cost of iproute.
>>
>> The -batch option almost works, but it's hard to programatically
>> figure out failure codes.
>>
>> I'm thinking about making these changes:
>>
>> 1)  Move all of the error printing code into common methods (basically,
>>     wrap printf).  In daemon mode this text can be sent back to the
>>     calling process, and in normal mode, it will be printed to stdout/stderr
>>     as it is currently.
>>
>> 2)  Remove all or most calls to 'exit' and instead return error codes
>>     to the calling logic.
>>
>> 3)  Add ability to listen on a unix socket for commands, basically treat
>>     them just like batch commands, one command per packet.
>>
>> 4)  Return well formatted error code and text response to calling process
>>     over the unix socket, maybe something like:
>>
>> RV: [errno or equiv, zero for success]\n
>> CMD: [ command string this relates to ]\n
>> [ Optional free form text ]
>>
>>
>> Does something like this have any chance of upstream inclusion?
>>
>> Thanks,
>> Ben
>>
>> --
>> Ben Greear<greearb@candelatech.com>
>> Candela Technologies Inc  http://www.candelatech.com
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-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com