[Lxc-users] IPC between containers

[Daniel Lezcano]

On 06/08/2010 07:55 AM, Nirmal Guhan wrote:
> On Mon, Jun 7, 2010 at 5:21 PM, Brian K. White<brian at aljex.com>  wrote:
>
>    
>> On 6/7/2010 7:51 PM, Nirmal Guhan wrote:
>>      
>>> Hi,
>>>
>>> Is there a way to use shared memory between the containers? Any other
>>> better/faster IPC mechanisms? I don't want to use sockets.
>>>
>>> Please let me know.
>>>        
>> Fifos on shared filesystem on the host?
>> Multiply hardlinked files on the host which appear in the same place in
>> each container?
>>
>> Except I don't know how you could safely allow more than one client
>> mount the fs except read-only, other than by means which are ultimately
>> sockets just with fs overhead on top of that. (various network and
>> distributed filesystems, and distributed ipc, distributed locking
>> systems, all are network based)
>>
>> Or if the multiple-hardlink idea doesn't actually work, I guess you
>> could put an incron job on the host which has access to all the
>> container's fs's and can watch a special directory in the same place in
>> all containers fs's and whenever a file is modified in one container,
>> incrond on the host notices and replicates it in all other containers.
>>
>> None of this sounds as good as ordinary socket communications, which is
>> my point.
>>
>> The whole point of a container is to ensure that exactly that (IPC)
>> can't happen so I am tempted to say if you don't want something which
>> contains, then don't use containers.
>>
>> --
>> bkw
>>
>>
>>      
> I would prefer using the RAM for performance, something like /dev/shm. I
> tried mounting /dev/shm of host on container using mount --bind and it
> works. I don't know if this is preferable though. Is there a similar
> implementation(to /dev/shm) that is more secure and can be used across
> containers? Or anything on the cards?
>    
If you share the filesystem, you can use a shared mapped file (this is 
what does posix shm in the /dev/shm location in fact).