Re: [Lxc-users] Using common rootfs for multiple containers
We have a particular use case, but we are achieving this using CernVM-FS (http://cernvm.cern.ch/portal/filesystem) to supply read-only root filesystems to many machines (with local caching), and then aufs or overlayfs (depending on the kernel version) to provide write support as others have suggested. Josh. On 10 Jul 2013, at 16:30, Rob Landley r...@landley.net wrote: On 07/08/2013 11:22:55 PM, Ajith Adapa wrote: Hi, I would like it know is it possible to create a single rootfs (might be in read-only mode) and share it among multiple containers ? Currently for every container we create its own unique rootfs. What would be the best place to look in code for using single rootfs across multiple containers. Well, some of us are waiting patiently for: http://lkml.indiana.edu/hypermail/linux/kernel/1303.1/02476.html But I'm not sure who to make puppy eyes at. (One does not simply make puppy eyes at Al Viro.) Rob -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk ___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users -- The Wellcome Trust Sanger Institute is operated by Genome Research Limited, a charity registered in England with number 1021457 and a company registered in England with number 2742969, whose registered office is 215 Euston Road, London, NW1 2BE. -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk ___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
Re: [Lxc-users] Using common rootfs for multiple containers
This sound really great. I was wondering if anyone uses user namespaces and shared rootfs? I got the roblem the skeleton of the ro-root on the host has uid 0 for the root files, but the guest maps them to nobody, so i cant use shared rootfs and user namespaces together. I cant think of a better solution than rsyncinging and uidmapshifting the rootfs for every container. Bye, Niklas -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk ___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
Re: [Lxc-users] Using common rootfs for multiple containers
Quoting Niklas Fuchs (nkfu...@yahoo.de): This sound really great. I was wondering if anyone uses user namespaces and shared rootfs? I got the roblem the skeleton of the ro-root on the host has uid 0 for the root files, but the guest maps them to nobody, so i cant use shared rootfs and user namespaces together. I cant think of a better solution than rsyncinging and uidmapshifting the rootfs for every container. Yeah that scenario has occurred to me before. I think a lightweight stackable fs which maps uids is going to be desirable. For a trivial first implementation it should be easy to do as a fuse fs. If you decide to pursue that, please to keep us uptodate! -serge -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk ___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
Re: [Lxc-users] Using common rootfs for multiple containers
I would like it know is it possible to create a single rootfs (might be in read-only mode) and share it among multiple containers ? At Dotcloud.com they use one basic OS rootfs. For each container they mount this OS rootfs read-only and use a union file-system (AUFS) to add a writable layer. Here are some pointers: PAAS Under the Hood, Episode 3: AUFS http://blog.dotcloud.com/kernel-secrets-from-the-paas-garage-part-34-a Lightweight Virtualization with namespaces, cgroups, and unioning filesystems: http://blog.dotcloud.com/scale11 (excellent slides!) Rob. http://freedomboxblog.nl -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk ___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
Re: [Lxc-users] Using common rootfs for multiple containers
Yes, this is possible. There are multiple approaches, for example: 1. Creating a snapshot (or outright copy) of a filesystem, then disposing of it when done. (1a) Manually creating a full copy (1b) Using a blockstore-provided snapshot facility such as LVM2 2. Using a snapshot-capable filesystem, and using a snapshot provided by the filesystem itself (ZFS, BTRFS, etc.) 3. Mounting read-only, with either of two solutions for writable portions of the filesystem. This class of solution is very similar to NFS based root situations (ie. modern PXE-driven diskless network boot). (3a) 'tmpfs' or some other in-memory based write solution where required. (3b) Union-mounts. My advice would be as follows. == simplest == (1a) and (1b) are easiest *and* allow the use of arbitrary filesystems. == medium hassle== (2) is become somewhat common but is more difficult. (3b) are more difficult == more hassle == (3a) is more hassle up front but is perhaps the neatest solution overall. (3b) i have never got working, but should be neat.. it's just not going to be as widely supported by various kernels out there as (3a) or (1b). Personally I use (3a) and (1b). - Walter -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk ___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
Re: [Lxc-users] Using common rootfs for multiple containers
Yes, it's possible. We do it. I can't share the code, but I can describe it. We create a master container using standard lxc-create script with our own template and config file. The template is based on the ubuntu template. The master container is never started. All subsequent containers share the rootfs of the master container. We use the lxc library to read the master container's config, then fork and call lxc_start to run a program in a new container using the config we read. But, you should be able to do this with scripts, if that is your choice. A couple of warnings. You need to create an empty directory in /var/lib/lxc for each container that matches the name specified in the lxc_start call. You must create the containers serially. This technique will fail if lxc-create is called concurrently by different threads or processes. We are using Ubuntu 12.04 LTS 64-bit. Regards. Mark K Vallevand mark.vallev...@unisys.commailto:mark.vallev...@unisys.com May you live in interesting times, may you come to the attention of important people and may all your wishes come true. THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers. From: Ajith Adapa [mailto:ajith.ad...@gmail.com] Sent: Monday, July 08, 2013 11:23 PM To: Lxc-users@lists.sourceforge.net Subject: [Lxc-users] Using common rootfs for multiple containers Hi, I would like it know is it possible to create a single rootfs (might be in read-only mode) and share it among multiple containers ? Currently for every container we create its own unique rootfs. What would be the best place to look in code for using single rootfs across multiple containers. Regards, Ajith -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
[Lxc-users] Using common rootfs for multiple containers
Hi, I would like it know is it possible to create a single rootfs (might be in read-only mode) and share it among multiple containers ? Currently for every container we create its own unique rootfs. What would be the best place to look in code for using single rootfs across multiple containers. Regards, Ajith -- See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831iu=/4140/ostg.clktrk___ Lxc-users mailing list Lxc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lxc-users
