X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fsystemd-nspawn.xml;h=fa0680ffcddba7ce3d271192eef6e648f2db6218;hp=7d450f912c1c617c17d6bd41a32eb0d87374963a;hb=f131770b1465fbf423881f16ba85523a05f846fe;hpb=79640424059328268b9fb6c5fa8eb777b27a177e diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml index 7d450f912..fa0680ffc 100644 --- a/man/systemd-nspawn.xml +++ b/man/systemd-nspawn.xml @@ -21,7 +21,8 @@ along with systemd; If not, see . --> - + systemd-nspawn @@ -69,7 +70,7 @@ systemd-nspawn may be used to run a command or OS in a light-weight namespace container. In many ways it is similar to - chroot1, + chroot1, but more powerful since it fully virtualizes the file system hierarchy, as well as the process tree, the various IPC subsystems and the host and domain @@ -97,15 +98,15 @@ involved with boot and systems management. In contrast to - chroot1 systemd-nspawn + chroot1 systemd-nspawn may be used to boot full Linux-based operating systems in a container. Use a tool like - yum8, - debootstrap8, + yum8, + debootstrap8, or - pacman8 + pacman8 to set up an OS directory tree suitable as file system hierarchy for systemd-nspawn containers. @@ -123,10 +124,10 @@ see each other. The PID namespace separation of the two containers is complete and the containers will share very few runtime objects except for the - underlying file system. It is however possible to - enter an existing container, see - Example 4 below. - + underlying file system. Use + machinectl1's + login command to request an + additional login prompt in a running container. systemd-nspawn implements the As a safety check systemd-nspawn will verify the - existence of /etc/os-release in - the container tree before starting the container (see + existence of /usr/lib/os-release + or /etc/os-release in the + container tree before starting the container (see os-release5). It might be necessary to add this file to the container tree manually if the OS of the container is too old to contain this file out-of-the-box. - - Incompatibility with Auditing - - Note that the kernel auditing subsystem is - currently broken when used together with - containers. We hence recommend turning it off entirely - by booting with audit=0 on the - kernel command line, or by turning it off at kernel - build time. If auditing is enabled in the kernel, - operating systems booted in an nspawn container might - refuse log-in attempts. - - Options @@ -172,29 +161,111 @@ - - + + - Prints a short help - text and exits. + Directory to use as + file system root for the container. + + If neither + , nor + is specified + the directory is determined as + /var/lib/container/ + suffixed by the machine name as + specified with + . If + neither , + , nor + are + specified, the current directory will + be used. May not be specified together + with + . - - - Prints a version string - and exits. + + + Directory or + btrfs subvolume to + use as template for the container's + root directory. If this is specified + and the container's root directory (as + configured by + ) does + not yet exist it is created as + btrfs subvolume and + populated from this template + tree. Ideally, the specified template + path refers to the root of a + btrfs subvolume, in + which case a simple copy-on-write + snapshot is taken, and populating the + root directory is instant. If the + specified template path does not refer + to the root of a + btrfs subvolume (or + not even to a btrfs + file system at all), the tree is + copied, which can be substantially + more time-consuming. Note that if this + option is used the container's root + directory (in contrast to the template + directory!) must be located on a + btrfs file system, + so that the btrfs + subvolume may be created. May not be + specified together with + or + . - - + + + + If specified, the + container is run with a temporary + btrfs snapshot of + its root directory (as configured with + ), that + is removed immediately when the + container terminates. This option is + only supported if the root file system + is btrfs. May not + be specified together with + or + . + - Directory to use as - file system root for the namespace - container. If omitted, the current - directory will be - used. + + + + + Disk image to mount + the root directory for the container + from. Takes a path to a regular file + or to a block device node. The file or + block device must contain a GUID + Partition Table with a root partition + which is mounted as the root directory + of the container. Optionally, it may + contain a home and/or a server data + partition which are mounted to the + appropriate places in the + container. All these partitions must + be identified by the partition types + defined by the Discoverable + Partitions Specification. Any + other partitions, such as foreign + partitions, swap partitions or EFI + system partitions are not mounted. May + not be specified together with + , + or + . @@ -204,9 +275,12 @@ Automatically search for an init binary and invoke it instead of a shell or a user supplied - program. If this option is used, arguments - specified on the command line are used - as arguments for the init binary. + program. If this option is used, + arguments specified on the command + line are used as arguments for the + init binary. This option may not be + combined with + . @@ -214,13 +288,15 @@ - Run the command - under specified user, create home - directory and cd into it. As rest - of systemd-nspawn, this is not - the security feature and limits - against accidental changes only. - + After transitioning + into the container, change to the + specified user-defined in the + container's user database. Like all + other systemd-nspawn features, this is + not a security feature and provides + protection against accidental + destructive operations + only. @@ -229,23 +305,22 @@ Sets the machine name for this container. This name may be - used to identify this container on the - host, and is used to initialize the - container's hostname (which the - container can choose to override, - however). If not specified, the last - component of the root directory of the - container is used. - - - - - - Make the container - part of the specified slice, instead - of the - machine.slice. - + used to identify this container during + its runtime (for example in tools like + machinectl1 + and similar), and is used to + initialize the container's hostname + (which the container can choose to + override, however). If not specified, + the last component of the root + directory path of the container is + used, possibly suffixed with a random + identifier in case + mode is + selected. If the root directory + selected is the host's root directory + the host's hostname is used as default + instead. @@ -259,24 +334,135 @@ + + + + Make the container + part of the specified slice, instead + of the default + machine.slice. + + + - Turn off networking in - the container. This makes all network - interfaces unavailable in the - container, with the exception of the - loopback device. + Disconnect networking + of the container from the host. This + makes all network interfaces + unavailable in the container, with the + exception of the loopback device and + those specified with + + and configured with + . If + this option is specified, the + CAP_NET_ADMIN capability will be added + to the set of capabilities the + container retains. The latter may be + disabled by using + . - + + + Assign the specified + network interface to the + container. This will remove the + specified interface from the calling + namespace and place it in the + container. When the container + terminates, it is moved back to the + host namespace. Note that + + implies + . This + option may be used more than once to + add multiple network interfaces to the + container. + - Mount the root file - system read-only for the + + + + Create a + macvlan interface + of the specified Ethernet network + interface and add it to the + container. A + macvlan interface + is a virtual interface that adds a + second MAC address to an existing + physical Ethernet link. The interface + in the container will be named after + the interface on the host, prefixed + with mv-. Note that + + implies + . This + option may be used more than once to + add multiple network interfaces to the container. + + + + Create a virtual + Ethernet link + (veth) between host + and container. The host side of the + Ethernet link will be available as a + network interface named after the + container's name (as specified with + ), prefixed + with ve-. The + container side of the Ethernet + link will be named + host0. Note that + + implies + . + + + + + + Adds the host side of + the Ethernet link created with + to the + specified bridge. Note that + + implies + . If + this option is used, the host side of + the Ethernet link will use the + vb- prefix instead + of ve-. + + + + + + + Sets the SELinux + security context to be used to label + processes in the container. + + + + + + + + Sets the SELinux security + context to be used to label files in + the virtual API file systems in the + container. + + + @@ -284,7 +470,7 @@ additional capabilities to grant the container. Takes a comma-separated list of capability names, see - capabilities7 + capabilities7 for more information. Note that the following capabilities will be granted in any way: CAP_CHOWN, @@ -300,7 +486,23 @@ CAP_SYS_PTRACE, CAP_SYS_TTY_CONFIG, CAP_SYS_RESOURCE, CAP_SYS_BOOT, CAP_AUDIT_WRITE, - CAP_AUDIT_CONTROL. + CAP_AUDIT_CONTROL. Also CAP_NET_ADMIN + is retained if + is + specified. If the special value + all is passed, all + capabilities are + retained. + + + + + + Specify one or more + additional capabilities to drop for + the container. This allows running the + container with fewer capabilities than + the default (see above). @@ -314,7 +516,9 @@ versa). Takes one of no, host, + try-host, guest, + try-guest, auto. If no, the journal is not linked. If host, @@ -328,8 +532,11 @@ guest file system (beneath /var/log/journal/machine-id) and the subdirectory is symlinked into the host - at the same location. If - auto (the default), + at the same location. try-host + and try-guest do the same + but do not fail if the host does not have + persistent journalling enabled. + If auto (the default), and the right subdirectory of /var/log/journal exists, it will be bind mounted @@ -348,7 +555,15 @@ Equivalent to - . + . + + + + + + Mount the root file + system read-only for the + container. @@ -368,63 +583,266 @@ destination in the container. The option creates read-only bind - mount. + mounts. + + + + + + Mount a tmpfs file + system into the container. Takes a + single absolute path argument that + specifies where to mount the tmpfs + instance to (in which case the + directory access mode will be chosen + as 0755, owned by root/root), or + optionally a colon-separated pair of + path and mount option string, that is + used for mounting (in which case the + kernel default for access mode and + owner will be chosen, unless otherwise + specified). This option is + particularly useful for mounting + directories such as + /var as tmpfs, to + allow state-less systems, in + particular when combined with + . + + + + + + Specifies an + environment variable assignment to + pass to the init process in the + container, in the format + NAME=VALUE. This + may be used to override the default + variables or to set additional + variables. This parameter may be used + more than once. + + + + + + Allows the container + to share certain system facilities + with the host. More specifically, this + turns off PID namespacing, UTS + namespacing and IPC namespacing, and + thus allows the guest to see and + interact more easily with processes + outside of the container. Note that + using this option makes it impossible + to start up a full Operating System in + the container, as an init system + cannot operate in this mode. It is + only useful to run specific programs + or applications this way, without + involving an init system in the + container. This option implies + . This + option may not be combined with + . + + + + + + Controls whether the + container is registered with + systemd-machined8. Takes + a boolean argument, defaults to + yes. This option + should be enabled when the container + runs a full Operating System (more + specifically: an init system), and is + useful to ensure that the container is + accessible via + machinectl1 + and shown by tools such as + ps1. If + the container does not run an init + system, it is recommended to set this + option to no. Note + that + implies + . + + + + + + Instead of creating a + transient scope unit to run the + container in, simply register the + service or scope unit + systemd-nspawn has + been invoked in with + systemd-machined8. This + has no effect if + is + used. This switch should be used if + systemd-nspawn is + invoked from within a service unit, + and the service unit's sole purpose + is to run a single + systemd-nspawn + container. This option is not + available if run from a user + session. + + + + + + Control the + architecture ("personality") reported + by + uname2 + in the container. Currently, only + x86 and + x86-64 are + supported. This is useful when running + a 32-bit container on a 64-bit + host. If this setting is not used, + the personality reported in the + container is the same as the one + reported on the + host. + + + + + + + Turns off any status + output by the tool itself. When this + switch is used, the only output + from nspawn will be the console output + of the container OS itself. + + + + =MODE + + Boots the container in + volatile mode. When no mode parameter + is passed or when mode is specified as + yes full volatile + mode is enabled. This means the root + directory is mounted as mostly + unpopulated tmpfs + instance, and + /usr from the OS + tree is mounted into it, read-only + (the system thus starts up with + read-only OS resources, but pristine + state and configuration, any changes + to the either are lost on + shutdown). When the mode parameter is + specified as state + the OS tree is mounted read-only, but + /var is mounted + as tmpfs instance + into it (the system thus starts up + with read-only OS resources and + configuration, but pristine state, any + changes to the latter are lost on + shutdown). When the mode parameter is + specified as no + (the default) the whole OS tree is + made available writable. + + Note that setting this to + yes or + state will only + work correctly with operating systems + in the container that can boot up with + only /usr + mounted, and are able to populate + /var + automatically, as + needed. + + + + - Example 1 + Examples + + Boot a minimal Fedora distribution in a container - # yum -y --releasever=19 --nogpg --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora install systemd passwd yum fedora-release vim-minimal + # yum -y --releasever=21 --nogpg --installroot=/srv/mycontainer --disablerepo='*' --enablerepo=fedora install systemd passwd yum fedora-release vim-minimal # systemd-nspawn -bD /srv/mycontainer - This installs a minimal Fedora distribution into - the directory /srv/mycontainer/ and - then boots an OS in a namespace container in - it. - + This installs a minimal Fedora distribution into + the directory /srv/mycontainer/ and + then boots an OS in a namespace container in + it. + - - Example 2 + + Spawn a shell in a container of a minimal Debian unstable distribution - # debootstrap --arch=amd64 unstable ~/debian-tree/ + # debootstrap --arch=amd64 unstable ~/debian-tree/ # systemd-nspawn -D ~/debian-tree/ - This installs a minimal Debian unstable - distribution into the directory - ~/debian-tree/ and then spawns a - shell in a namespace container in it. - + This installs a minimal Debian unstable + distribution into the directory + ~/debian-tree/ and then spawns a + shell in a namespace container in it. + - - Example 3 + + Boot a minimal Arch Linux distribution in a container - # pacstrap -c -d ~/arch-tree/ base + # pacstrap -c -d ~/arch-tree/ base # systemd-nspawn -bD ~/arch-tree/ - This installs a mimimal Arch Linux distribution into - the directory ~/arch-tree/ and then - boots an OS in a namespace container in it. - + This installs a mimimal Arch Linux distribution into + the directory ~/arch-tree/ and then + boots an OS in a namespace container in it. + + + + Enable Arch Linux container on boot + + # mv ~/arch-tree /var/lib/container/arch +# systemctl enable systemd-nspawn@arch.service +# systemctl start systemd-nspawn@arch.service + + This makes the Arch Linux container part of the + multi-user.target on the host. + + + + + Boot into an ephemeral <literal>btrfs</literal> snapshot of the host system - - Example 4 + # systemd-nspawn -D / -xb - To enter the container, PID of one of the - processes sharing the new namespaces must be used. - systemd-nspawn prints the PID - (as viewed from the outside) of the launched process, - and it can be used to enter the container. + This runs a copy of the host system in a + btrfs snapshot which is + removed immediately when the container + exits. All file system changes made during + runtime will be lost on shutdown, + hence. + - # nsenter -m -u -i -n -p -t $PID + + Run a container with SELinux sandbox security contexts - nsenter1 - is part of - util-linux. - Kernel support for entering namespaces was added in - Linux 3.8. + # chcon system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -R /srv/container +# systemd-nspawn -L system_u:object_r:svirt_sandbox_file_t:s0:c0,c1 -Z system_u:system_r:svirt_lxc_net_t:s0:c0,c1 -D /srv/container /bin/sh + @@ -438,12 +856,13 @@ See Also systemd1, - chroot1, - unshare1, - yum8, - debootstrap8, - pacman8, - systemd.slice5 + chroot1, + yum8, + debootstrap8, + pacman8, + systemd.slice5, + machinectl1, + btrfs8