diff options
Diffstat (limited to 'man/systemd-nspawn.xml')
| -rw-r--r-- | man/systemd-nspawn.xml | 186 |
1 files changed, 132 insertions, 54 deletions
diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml index 86cdb4e124..0c8c699201 100644 --- a/man/systemd-nspawn.xml +++ b/man/systemd-nspawn.xml @@ -58,7 +58,7 @@ </cmdsynopsis> <cmdsynopsis> <command>systemd-nspawn</command> - <arg choice="plain">-b</arg> + <arg choice="plain">--boot</arg> <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt" rep="repeat">ARGS</arg> </cmdsynopsis> @@ -263,7 +263,7 @@ signals. It is recommended to use this mode to invoke arbitrary commands in containers, unless they have been modified to run correctly as PID 1. Or in other words: this switch should be used for pretty much all commands, except when the command refers to an init or shell implementation, as these are generally capable of running - correctly as PID 1). This option may not be combined with <option>--boot</option> or + correctly as PID 1. This option may not be combined with <option>--boot</option> or <option>--share-system</option>.</para> </listitem> </varlistentry> @@ -294,12 +294,12 @@ <tbody> <row> <entry>Neither <option>--as-pid2</option> nor <option>--boot</option> specified</entry> - <entry>The passed parameters are interpreted as command line, which is executed as PID 1 in the container.</entry> + <entry>The passed parameters are interpreted as the command line, which is executed as PID 1 in the container.</entry> </row> <row> <entry><option>--as-pid2</option> specified</entry> - <entry>The passed parameters are interpreted as command line, which are executed as PID 2 in the container. A stub init process is run as PID 1.</entry> + <entry>The passed parameters are interpreted as the command line, which is executed as PID 2 in the container. A stub init process is run as PID 1.</entry> </row> <row> @@ -355,7 +355,9 @@ <listitem><para>Set the specified UUID for the container. The init system will initialize <filename>/etc/machine-id</filename> from this if this file is - not set yet. </para></listitem> + not set yet. Note that this option takes effect only if + <filename>/etc/machine-id</filename> in the container is + unpopulated.</para></listitem> </varlistentry> <varlistentry> @@ -385,38 +387,79 @@ <varlistentry> <term><option>--private-users=</option></term> - <listitem><para>Enables user namespacing. If enabled, the - container will run with its own private set of Unix user and - group ids (UIDs and GIDs). Takes none, one or two - colon-separated parameters: the first parameter specifies the - first host UID to assign to the container, the second - parameter specifies the number of host UIDs to assign to the - container. If the second parameter is omitted, 65536 UIDs are - assigned. If the first parameter is also omitted (and hence - no parameter passed at all), the first UID assigned to the - container is read from the owner of the root directory of the - container's directory tree. By default, no user namespacing is - applied.</para> - - <para>Note that user namespacing currently requires OS trees - that are prepared for the UID shift that is being applied: - UIDs and GIDs used for file ownership or in file ACL entries - must be shifted to the container UID base that is - used during container runtime.</para> + <listitem><para>Controls user namespacing. If enabled, the container will run with its own private set of UNIX + user and group ids (UIDs and GIDs). This involves mapping the private UIDs/GIDs used in the container (starting + with the container's root user 0 and up) to a range of UIDs/GIDs on the host that are not used for other + purposes (usually in the range beyond the host's UID/GID 65536). The parameter may be specified as follows:</para> + + <orderedlist> + <listitem><para>The value <literal>no</literal> turns off user namespacing. This is the default.</para></listitem> + + <listitem><para>The value <literal>yes</literal> (or the omission of a parameter) turns on user + namespacing. The UID/GID range to use is determined automatically from the file ownership of the root + directory of the container's directory tree. To use this option, make sure to prepare the directory tree in + advance, and ensure that all files and directories in it are owned by UIDs/GIDs in the range you'd like to + use. Also, make sure that used file ACLs exclusively reference UIDs/GIDs in the appropriate range. If this + mode is used the number of UIDs/GIDs assigned to the container for use is 65536, and the UID/GID of the + root directory must be a multiple of 65536.</para></listitem> + + <listitem><para>The value "pick" turns on user namespacing. In this case the UID/GID range is automatically + chosen. As first step, the file owner of the root directory of the container's directory tree is read, and it + is checked that it is currently not used by the system otherwise (in particular, that no other container is + using it). If this check is successful, the UID/GID range determined this way is used, similar to the + behaviour if "yes" is specified. If the check is not successful (and thus the UID/GID range indicated in the + root directory's file owner is already used elsewhere) a new – currently unused – UID/GID range of 65536 + UIDs/GIDs is randomly chosen between the host UID/GIDs of 524288 and 1878982656, always starting at a + multiple of 65536. This setting implies <option>--private-users-chown</option> (see below), which has the + effect that the files and directories in the container's directory tree will be owned by the appropriate + users of the range picked. Using this option makes user namespace behaviour fully automatic. Note that the + first invocation of a previously unused container image might result in picking a new UID/GID range for it, + and thus in the (possibly expensive) file ownership adjustment operation. However, subsequent invocations of + the container will be cheap (unless of course the picked UID/GID range is assigned to a different use by + then).</para></listitem> + + <listitem><para>Finally if one or two colon-separated numeric parameters are specified, user namespacing is + turned on, too. The first parameter specifies the first host UID/GID to assign to the container, the second + parameter specifies the number of host UIDs/GIDs to assign to the container. If the second parameter is + omitted, 65536 UIDs/GIDs are assigned.</para></listitem> + </orderedlist> + + <para>It is recommended to assign at least 65536 UIDs/GIDs to each container, so that the usable UID/GID range in the + container covers 16 bit. For best security, do not assign overlapping UID/GID ranges to multiple containers. It is + hence a good idea to use the upper 16 bit of the host 32-bit UIDs/GIDs as container identifier, while the lower 16 + bit encode the container UID/GID used. This is in fact the behaviour enforced by the + <option>--private-users=pick</option> option.</para> + + <para>When user namespaces are used, the GID range assigned to each container is always chosen identical to the + UID range.</para> + + <para>In most cases, using <option>--private-users=pick</option> is the recommended option as it enhances + container security massively and operates fully automatically in most cases.</para> + + <para>Note that the picked UID/GID range is not written to <filename>/etc/passwd</filename> or + <filename>/etc/group</filename>. In fact, the allocation of the range is not stored persistently anywhere, + except in the file ownership of the files and directories of the container.</para></listitem> + </varlistentry> - <para>It is recommended to assign at least 65536 UIDs to each - container, so that the usable UID range in the container - covers 16 bit. For best security, do not assign overlapping UID - ranges to multiple containers. It is hence a good idea to use - the upper 16 bit of the host 32-bit UIDs as container - identifier, while the lower 16 bit encode the container UID - used.</para> + <varlistentry> + <term><option>-U</option></term> - <para>When user namespaces are used, the GID range assigned to - each container is always chosen identical to the UID - range.</para></listitem> + <listitem><para>If the kernel supports the user namespaces feature, equivalent to + <option>--private-users=pick</option>, otherwise equivalent to + <option>--private-users=no</option>.</para></listitem> </varlistentry> + <varlistentry> + <term><option>--private-users-chown</option></term> + + <listitem><para>If specified, all files and directories in the container's directory tree will adjusted so that + they are owned to the appropriate UIDs/GIDs selected for the container (see above). This operation is + potentially expensive, as it involves descending and iterating through the full directory tree of the + container. Besides actual file ownership, file ACLs are adjusted as well.</para> + + <para>This option is implied if <option>--private-users=pick</option> is used. This option has no effect if + user namespacing is not used.</para></listitem> + </varlistentry> <varlistentry> <term><option>--private-network</option></term> @@ -481,15 +524,23 @@ <term><option>-n</option></term> <term><option>--network-veth</option></term> - <listitem><para>Create a virtual Ethernet link - (<literal>veth</literal>) 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 - <option>--machine=</option>), prefixed with - <literal>ve-</literal>. The container side of the Ethernet - link will be named <literal>host0</literal>. Note that - <option>--network-veth</option> implies - <option>--private-network</option>.</para></listitem> + <listitem><para>Create a virtual Ethernet link (<literal>veth</literal>) 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 <option>--machine=</option>), prefixed with <literal>ve-</literal>. The container side of the + Ethernet link will be named <literal>host0</literal>. The <option>--network-veth</option> option implies + <option>--private-network</option>.</para> + + <para>Note that + <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> + includes by default a network file <filename>/usr/lib/systemd/network/80-container-ve.network</filename> + matching the host-side interfaces created this way, which contains settings to enable automatic address + provisioning on the created virtual link via DHCP, as well as automatic IP routing onto the host's external + network interfaces. It also contains <filename>/usr/lib/systemd/network/80-container-host0.network</filename> + matching the container-side interface created this way, containing settings to enable client side address + assignment via DHCP. In case <filename>systemd-networkd</filename> is running on both the host and inside the + container, automatic IP communication from the container to the host is thus available, with further + connectivity to the external network.</para> + </listitem> </varlistentry> <varlistentry> @@ -500,7 +551,7 @@ host interface name and container interface name. The latter may be omitted in which case the container and host sides will be assigned the same name. This switch is independent of - <option>--network-veth</option>, and -- in contrast -- may be + <option>--network-veth</option>, and — in contrast — may be used multiple times, and allows configuration of the network interface names. Note that <option>--network-bridge=</option> has no effect on interfaces created with @@ -510,16 +561,43 @@ <varlistentry> <term><option>--network-bridge=</option></term> - <listitem><para>Adds the host side of the Ethernet link - created with <option>--network-veth</option> to the specified - bridge. Note that <option>--network-bridge=</option> implies - <option>--network-veth</option>. If this option is used, the - host side of the Ethernet link will use the - <literal>vb-</literal> prefix instead of + <listitem><para>Adds the host side of the Ethernet link created with <option>--network-veth</option> to the + specified Ethernet bridge interface. Expects a valid network interface name of a bridge device as + argument. Note that <option>--network-bridge=</option> implies <option>--network-veth</option>. If this option + is used, the host side of the Ethernet link will use the <literal>vb-</literal> prefix instead of <literal>ve-</literal>.</para></listitem> </varlistentry> <varlistentry> + <term><option>--network-zone=</option></term> + + <listitem><para>Creates a virtual Ethernet link (<literal>veth</literal>) to the container and adds it to an + automatically managed Ethernet bridge interface. The bridge interface is named after the passed argument, + prefixed with <literal>vz-</literal>. The bridge interface is automatically created when the first container + configured for its name is started, and is automatically removed when the last container configured for its + name exits. Hence, each bridge interface configured this way exists only as long as there's at least one + container referencing it running. This option is very similar to <option>--network-bridge=</option>, besides + this automatic creation/removal of the bridge device.</para> + + <para>This setting makes it easy to place multiple related containers on a common, virtual Ethernet-based + broadcast domain, here called a "zone". Each container may only be part of one zone, but each zone may contain + any number of containers. Each zone is referenced by its name. Names may be chosen freely (as long as they form + valid network interface names when prefixed with <literal>vz-</literal>), and it is sufficient to pass the same + name to the <option>--network-zones=</option> switch of the various concurrently running containers to join + them in one zone.</para> + + <para>Note that + <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> + includes by default a network file <filename>/usr/lib/systemd/network/80-container-vz.network</filename> + matching the bridge interfaces created this way, which contains settings to enable automatic address + provisioning on the created virtual network via DHCP, as well as automatic IP routing onto the host's external + network interfaces. Using <option>--network-zone=</option> is hence in most cases fully automatic and + sufficient to connect multiple local containers in a joined broadcast domain to the host, with further + connectivity to the external network.</para> + </listitem> + </varlistentry> + + <varlistentry> <term><option>-p</option></term> <term><option>--port=</option></term> @@ -534,7 +612,7 @@ port number and its colon may be omitted, in which case the same port as the host port is implied. This option is only supported if private networking is used, such as with - <option>--network-veth</option> or + <option>--network-veth</option>, <option>--network-zone=</option> <option>--network-bridge=</option>.</para></listitem> </varlistentry> @@ -595,9 +673,8 @@ order to trigger an orderly shutdown of the container. Defaults to SIGRTMIN+3 if <option>--boot</option> is used (on systemd-compatible init systems SIGRTMIN+3 - triggers an orderly shutdown). Takes a signal name like - <literal>SIGHUP</literal>, <literal>SIGTERM</literal> or - similar as argument.</para></listitem> + triggers an orderly shutdown). For a list of valid signals, see + <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem> </varlistentry> <varlistentry> @@ -736,7 +813,8 @@ </varlistentry> <varlistentry> - <term><option>--setenv=</option></term> + <term><option>-E <replaceable>NAME</replaceable>=<replaceable>VALUE</replaceable></option></term> + <term><option>--setenv=<replaceable>NAME</replaceable>=<replaceable>VALUE</replaceable></option></term> <listitem><para>Specifies an environment variable assignment to pass to the init process in the container, in the format |