lxc configuration help - only network isolated?
I have a couple of basic configuration questions on linux containers. I'm using lxc-0.6.1.
I'm trying to configure a setup where I have two containers, where the only virtualized/isolated resources are network resources, but I can still do IPC between processes in the two containers.
The lxc.conf man page indicates that, "by default, the pids, sysv ipc, and mount points are virtualized and isolated. "
Is there a way in the configuration to specify that those resources should NOT be isolated? I'd really like to have communication between two processes running in different containers using sysV IPC and signals. The only thing I really want to be isolated are two different network namespaces.
Is there a setting I use in the lxc.conf file to accomplish this?
Up to now, I've been doing some prototyping using lxc-unshare -n, but that doesn't really create a container, correct? That mostly accomplishes my goals, but I can't find a way to spawn new processes into that same namespace. Is there a way, without defining a container?
Any recommendations on how to properly configure a containers to allow IPC between processes in two different containers while still isolating the network resources?
Thanks,
Chris
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Quoted 11 lines · Chris R. Jones
I have a couple of basic configuration questions on linux containers. I'm using lxc-0.6.1.
I'm trying to configure a setup where I have two containers, where the only virtualized/isolated resources are network resources, but I can still do IPC between processes in the two containers.
The lxc.conf man page indicates that, "by default, the pids, sysv ipc, and mount points are virtualized and isolated. "
Is there a way in the configuration to specify that those resources should NOT be isolated? I'd really like to have communication between two processes running in different containers using sysV IPC and signals. The only thing I really want to be isolated are two different network namespaces.
Is there a setting I use in the lxc.conf file to accomplish this?
I thought no one would be interested by less isolation :)
I see you want to share the signals, that means no pid namespace, right ?
The design of the lxc is build around the pid namespace, if you kill the first process of the pid namespace, you kill all the process of the container. That allows to implement the 'lxc-stop' command.
So no pid namespace, no container :)
Quoted 2 lines
Up to now, I've been doing some prototyping using lxc-unshare -n, but that doesn't really create a container, correct? That mostly accomplishes my goals, but I can't find a way to spawn new processes into that same namespace. Is there a way, without defining a container?
No, except writing a forker and launch it inside the container and have a command outside to tell the forker to spawn a specific program. Dietmar Maurer is working on such component to be integrated in lxc.
Quoted 2 lines
Any recommendations on how to properly configure a containers to allow IPC between processes in two different containers while still isolating the network resources?
If you want to share the ipc to do some testing, you can hack the lxc_start function in start.c and remove the ipc cloning flag.
- clone_flags = CLONE_NEWPID|CLONE_NEWIPC|CLONE_NEWNS; +clone_flags = CLONE_NEWPID|CLONE_NEWNS;
I hope that helps.
-- Daniel
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Quoted 14 lines · Daniel Lezcano
Quoted 11 lines · Chris R. Jones
I have a couple of basic configuration questions on linux containers. I'm using lxc-0.6.1.
I'm trying to configure a setup where I have two containers, where the only virtualized/isolated resources are network resources, but I can still do IPC between processes in the two containers.
The lxc.conf man page indicates that, "by default, the pids, sysv ipc, and mount points are virtualized and isolated. "
Is there a way in the configuration to specify that those resources should NOT be isolated? I'd really like to have communication between two processes running in different containers using sysV IPC and signals. The only thing I really want to be isolated are two different network namespaces.
Is there a setting I use in the lxc.conf file to accomplish this?
I thought no one would be interested by less isolation :)
Quoted 7 lines
I see you want to share the signals, that means no pid namespace, right ?
The design of the lxc is build around the pid namespace, if you kill the first process of the pid namespace, you kill all the process of the container. That allows to implement the 'lxc-stop' command.
So no pid namespace, no container :)
There has been discussion before about having a 'kill' or 'signal' cgroup, analogous to the freezer, for sending signals to all tasks in a cgroup. We could push that, and have lxc-stop optionally use that.
If there were interest.
Quoted 9 lines
Quoted 2 lines
Up to now, I've been doing some prototyping using lxc-unshare -n, but that doesn't really create a container, correct? That mostly accomplishes my goals, but I can't find a way to spawn new processes into that same namespace. Is there a way, without defining a container?
No, except writing a forker and launch it inside the container and have a command outside to tell the forker to spawn a specific program. Dietmar Maurer is working on such component to be integrated in lxc.
Quoted 2 lines
Any recommendations on how to properly configure a containers to allow IPC between processes in two different containers while still isolating the network resources?
Quoted 7 lines
If you want to share the ipc to do some testing, you can hack the
lxc_startfunction instart.cand remove the ipc cloning flag.-
clone_flags= CLONE_NEWPID|CLONE_NEWIPC|CLONE_NEWNS; +clone_flags = CLONE_NEWPID|CLONE_NEWNS;I hope that helps.
I've heard this request in other places, especially about ipc, so maybe it's a good idea to work such support into the config. Maybe something like:
keep_sharing=CLONE_NEWIPC
in lxc.conf, and mask keep_sharing out of clone_flags at lxc_start?
-serge
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Quoted 21 lines · Serge E. Hallyn
Quoted 20 lines · Daniel Lezcano
Quoted 11 lines · Chris R. Jones
I have a couple of basic configuration questions on linux containers. I'm using lxc-0.6.1.
I'm trying to configure a setup where I have two containers, where the only virtualized/isolated resources are network resources, but I can still do IPC between processes in the two containers.
The lxc.conf man page indicates that, "by default, the pids, sysv ipc, and mount points are virtualized and isolated. "
Is there a way in the configuration to specify that those resources should NOT be isolated? I'd really like to have communication between two processes running in different containers using sysV IPC and signals. The only thing I really want to be isolated are two different network namespaces.
Is there a setting I use in the lxc.conf file to accomplish this?
I thought no one would be interested by less isolation :)
I see you want to share the signals, that means no pid namespace, right ?
The design of the lxc is build around the pid namespace, if you kill the first process of the pid namespace, you kill all the process of the container. That allows to implement the 'lxc-stop' command.
Quoted 8 lines
Quoted 1 line
So no pid namespace, no container :)
There has been discussion before about having a 'kill' or 'signal' cgroup, analogous to the freezer, for sending signals to all tasks in a cgroup. We could push that, and have lxc-stop optionally use that.
If there were interest.
I've got some ancient patches for that! :) I think we'd want to use Paul Menage's recent empty hierarchy, multiply-bound, and stateless subsystem patches for a signal subsystem. In fact, it may be such a simple task that using the old patches would be more of a hindrance...
Cheers,
-Matt Helsley