[lxc-users] Communication btw container & host

[Fajar A. Nugraha]

Depends on how you setup a container, there are several options:

(1) on each new container, run "systemctl disable" for every unneeded
services. OR

(2) don't use host /usr and /lib directly, but use unionfs or similar
(so you have a private "copy" for each container) and uninstall any
unneeded service in each container. OR

(3) don't use bind mount or unionfs, but use a clone-capable fs (e.g.
btrfs, zfs), and then uninstall any unneeded services in each
container

-- 
Fajar


On Tue, Aug 25, 2015 at 10:16 AM, SIVA SUBRAMANIAN.P <psiva87 at gmail.com> wrote:
> Thanks Fajar, Appreciate your effort. I'm trying to bring up systemd
> container on the linux host and want to containerize only a set of systemd
> services. Is there any way to restrict it? Since lib is mounted from host,
> container starts all the services inside /lib/systemd/system as like in
> host.
>
> On Tue, Aug 18, 2015 at 8:47 PM, Fajar A. Nugraha <list at fajar.net> wrote:
>>
>> Short version: you might be thinking about docker.
>>
>> Long version:
>>
>> Think of lxc as lightweight virtual machines. You'd define any
>> "dependency" the same way you do on clusters of real servers: basically
>> there isn't any, admins must take care of starting VMs in order and making
>> sure the needed services are ready before the next one is started, or write
>> their own scripts to handle the dependency. Each container would communicate
>> with other containers using network, the same way it would on real servers.
>>
>> If all you need is a simple "VM A must be started before VM B without the
>> need to check wheter the services are already running (i.e. whatever is in B
>> is smart enough to wait until services in A are ready)", then lxc has
>> autstart grouping and ordering. Run "man lxc.container.conf", look for
>> "AUTOSTART"
>>
>> Docker, on the other hand, is different from lxc. It uses the same linux
>> kernel capabilities as lxc, but has different user space and configuration.
>> Some of the differences:
>> - docker treats each container as an "application" instead of a full VM
>> (so for example, typically you won't be able to "ssh" into a docker
>> container)
>> - docker supports dependencies between containers, either by checking a
>> process, tcp port, or a custom script
>>
>> If you think docker is more suitable for your needs, head over to their
>> website/user mailing list and ask for more info there.
>>
>> --
>> Fajar
>>
>>
>> On Wed, Aug 19, 2015 at 8:12 AM, SIVA SUBRAMANIAN.P <psiva87 at gmail.com>
>> wrote:
>>>
>>> Thanks Andrey for taking effort. Appreciate it.
>>> Let say I want to run a application which is dependent on lighttpd
>>> webservice. Can I run it outside the container where that application runs
>>> and how it will communicate?
>>>
>>> On Tue, Aug 18, 2015 at 5:28 PM, Andrey Repin <anrdaemon at yandex.ru>
>>> wrote:
>>>>
>>>> Greetings, SIVA SUBRAMANIAN.P!
>>>>
>>>> > Can some one throw light on the communication option available between
>>>> > the
>>>> > host and container. I'm planning to run main application in container
>>>> > and all its dependencies outside it.
>>>>
>>>> Define "dependencies"?
>>>> Without knowing, what exactly you want to do, there's no way to tell
>>>> you, how
>>>> you can achieve your desired result.
>>>>
>>>>
>>>> --
>>>> With best regards,
>>>> Andrey Repin
>>>> Wednesday, August 19, 2015 03:27:26
>>>>
>>>> Sorry for my terrible english...
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>>>> http://lists.linuxcontainers.org/listinfo/lxc-users
>>>
>>>
>>>
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>>
>>
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>
>
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