vzctl - utility to control an OpenVZ container.
vzctl [flags] create CTID --ostemplate name]
[--config name] [--private path] [--root
path] [--ipadd addr] [--hostname name]
vzctl [flags] set CTID [parameters]
[--save]
vzctl [flags] destroy | mount | umount
| start | stop | restart | status | enter
CTID
vzctl [flags] exec | exec2 CTID
command [arg ...]
vzctl runscript CTID script
vzctl --help | --version
Utility vzctl runs on the host system (otherwise known as Hardware Node,
or HN) and performs direct manipulations with containers (CTs).
Containers can be referred to by either numeric CTID or by
name (see --name option). Note that CT ID <= 100 are reserved for
OpenVZ internal purposes.
These flags can be used with almost any option.
- --quiet
- Disables logging to log file and screen.
- --verbose
- Sets logging level to maximum value.
- set CTID [parameters] [--save]
- This command sets various container parameters. If a --save flag is
given, parameters are saved in container configuration file
vps.conf(5). If a container is currently running, vzctl
applies these parameters to the container.
The following options can be used with set command.
- Miscellaneous parameters
- --onboot yes|no
- Sets whether this container will be started during system boot up. The
container will not be auto-started during system boot up unless this
parameter is set to yes.
- --root path
- Sets the path to root directory for this container. This is essentially a
mount point for container's root directory. The value must contain string
$VEID, which will be substituted with the numeric CT ID. Changing
this parameter is not recommended, better edit vz.conf(5) global
configuration file.
- --userpasswd user:password
- Sets password for the given user in a container, creating the user if it
does not exists. Note that this option is not saved in configuration file
at all (so --save flag is useless), it is applied to the container
(by modifying its /etc/passwd and
/etc/shadow files).
In case container root filesystem is not mounted, it is
automatically mounted, then all the appropriate file changes are
applied, then it is unmounted.
Note that container files should be created before using this
option.
- --disabled yes|no
- Disable container start. To force the start of a disabled container, use
vzctl start with --force option.
- --name name
- Add a name for a container. The name can later be used in
subsequent calls to vzctl in place of CTID.
- --setmode restart|ignore
- Whether to restart a container after applying any parameters requiring
that the container be restarted for those to take effect.
- Network related parameters
- --ipadd addr
- Adds IP address to a given container. Note that this option is
incremental, so addr are added to already existing ones.
- --ipdel addr | all
- Removes IP address addr from a container. If you want to remove all
the addresses, use --ipdel all.
- --hostname name
- Sets container hostname. vzctl writes it to the appropriate file
inside a container (distribution-dependent).
- --nameserver addr
- Sets DNS server IP address for a container. If you want to set several
nameservers, you should do it at once, so use --nameserver option
multiple times in one call to vzctl, as all the name server values
set in previous calls to vzctl gets overwritten.
- --searchdomain name
- Sets DNS search domains for a container. If you want to set several search
domains, you should do it at once, so use --searchdomain option
multiple times in one call to vzctl, as all the search domain
values set in previous calls to vzctl gets overwritten.
- --netif_add
ifname[,mac,host_ifname,host_mac]
- Adds a virtual ethernet device (veth) to a given container. Here
ifname is the ethernet device name in the container, mac is
its MAC address, host_ifname is the ethernet device name on the
host, and host_mac is its MAC address. MAC addresses should be in
the format like XX:XX:XX:XX:XX:XX. All parameters except ifname are
optional and are automatically generated if not specified.
- --netif_del dev_name|all
- Removes virtual ethernet device from a container. If you want to remove
all devices, use all.
- Interface configuration
-
The following options can be used to reconfigure the
already-created virtual ethernet interface. To select the interface to
configure, use --ifname name option.
- --mac XX:XX:XX:XX:XX:XX
- MAC address of interface inside a container.
- --host_ifname name
- interface name for virtual interface in the host system.
- --host_mac XX:XX:XX:XX:XX:XX
- MAC address of interface in the host system.
- --mac_filter on|off
- Enables/disables MAC address filtering for the Container veth device and
the possibility of configuring the MAC address of this device from inside
the Container. If the filtering is turned on:
* the veth device accepts only those packets that have a MAC address in
their headers corresponding to that of this device (excluding all
broadcast and multicast packets);
* it is impossible to modify the veth MAC address from inside the Container.
By default, this functionality is enabled for all veth devices existing
inside the Container.
- Resource limits
-
The following options sets barrier and limit for various user
beancounters. Each option requires one or two arguments. In case of one
argument, vzctl sets barrier and limit to the same value. In case
of two colon-separated arguments, the first is a barrier, and the second
is a limit. Each argument is either a number, a number with a suffix, or
a special value unlimited.
Arguments are in items, pages or bytes. Note that page size is
architecture-specific, it is 4096 bytes on IA32 platform.
You can also specify different suffixes for set
parameters (except for the parameters which names start with
num). For example, vzctl set CTID --privvmpages
5M:6M should set privvmpages' barrier to 5 megabytes and its
limit to 6 megabytes.
Available suffixes are:
g, G -- gigabytes.
m, M -- megabytes.
k, K -- kilobytes.
p, P -- pages (page is 4096 bytes on x86 architecture, other
architectures may differ).
You can also specify the literal word unlimited in
place of a number. In that case the corresponding value will be set to
LONG_MAX, i. e. the maximum possible value.
- --numproc items[:items]
- Maximum number of processes and kernel-level threads. Setting the barrier
and the limit to different values does not make practical sense.
- --numtcpsock items[:items]
- Maximum number of TCP sockets. This parameter limits the number of TCP
connections and, thus, the number of clients the server application can
handle in parallel. Setting the barrier and the limit to different values
does not make practical sense.
- --numothersock items[:items]
- Maximum number of non-TCP sockets (local sockets, UDP and other types of
sockets). Setting the barrier and the limit to different values does not
make practical sense.
- --vmguarpages pages[:pages]
- Memory allocation guarantee. This parameter controls how much memory is
available to a container. The barrier is the amount of memory that
container's applications are guaranteed to be able to allocate. The
meaning of the limit is currently unspecified; it should be set to
unlimited.
- --kmemsize bytes[:bytes]
- Maximum amount of kernel memory used. This parameter is related to
--numproc. Each process consumes certain amount of kernel memory -
16 KB at leas, 30-50 KB typically. Very large processes may consume a bit
more. It is important to have a certain safety gap between the barrier and
the limit of this parameter: equal barrier and limit may lead to the
situation where the kernel will need to kill container's applications to
keep the kmemsize usage under the limit.
- --tcpsndbuf bytes[:bytes]
- Maximum size of TCP send buffers. Barrier should be not less than 64 KB,
and difference between barrier and limit should be equal to or more than
value of numtcpsock multiplied by 2.5 KB.
- --tcprcvbuf bytes[:bytes]
- Maximum size of TCP receive buffers. Barrier should be not less than 64
KB, and difference between barrier and limit should be equal to or more
than value of numtcpsock multiplied by 2.5 KB.
- --othersockbuf bytes[:bytes]
- Maximum size of other (non-TCP) socket send buffers. If container's
processes needs to send very large datagrams, the barrier should be set
accordingly. Increased limit is necessary for high performance of
communications through local (UNIX-domain) sockets.
- --dgramrcvbuf bytes[:bytes]
- Maximum size of other (non-TCP) socket receive buffers. If container's
processes needs to receive very large datagrams, the barrier should be set
accordingly. The difference between the barrier and the limit is not
needed.
- --oomguarpages pages[:pages]
- Guarantees against OOM kill. Under this beancounter the kernel accounts
the total amount of memory and swap space used by the container's
processes. The barrier of this parameter is the out-of-memory guarantee.
If the oomguarpages usage is below the barrier, processes of this
container are guaranteed not to be killed in out-of-memory situations. The
meaning of limit is currently unspecified; it should be set to
unlimited.
- --lockedpages pages[:pages]
- Maximum number of pages acquired by mlock(2).
- --privvmpages pages[:pages]
- Allows controlling the amount of memory allocated by the applications. For
shared (mapped as MAP_SHARED) pages, each container really using a
memory page is charged for the fraction of the page (depending on the
number of others using it). For "potentially private" pages
(mapped as MAP_PRIVATE), container is charged either for a fraction
of the size or for the full size if the allocated address space. In the
latter case, the physical pages associated with the allocated address
space may be in memory, in swap or not physically allocated yet.
The barrier and the limit of this parameter control the upper
boundary of the total size of allocated memory. Note that this upper
boundary does not guarantee that container will be able to allocate that
much memory. The primary mechanism to control memory allocation is the
--vmguarpages guarantee.
- --shmpages pages[:pages]
- Maximum IPC SHM segment size. Setting the barrier and the limit to
different values does not make practical sense.
- --numfile items[:items]
- Maximum number of open files. Setting the barrier and the limit to
different values does not make practical sense.
- --numflock items[:items]
- Maximum number of file locks. Safety gap should be between barrier and
limit.
- --numpty items[:items]
- Number of pseudo-terminals (PTY). Note that in OpenVZ each container can
have not more than 255 PTYs. Setting the barrier and the limit to
different values does not make practical sense.
- --numsiginfo items[:items]
- Number of siginfo structures. Setting the barrier and the limit to
different values does not make practical sense.
- --dcachesize bytes[:bytes]
- Maximum size of filesystem-related caches, such as directory entry and
inode caches. Exists as a separate parameter to impose a limit causing
file operations to sense memory shortage and return an errno to
applications, protecting from memory shortages during critical operations
that should not fail. Safety gap should be between barrier and limit.
- --numiptent num[:num]
- Number of iptables (netfilter) entries. Setting the barrier and the limit
to different values does not make practical sense.
- --physpages pages[:pages]
- This is currently an accounting-only parameter. It shows the usage of RAM
by this container. Barrier should be set to 0, and limit should be set to
unlimited.
- CPU fair scheduler parameters
-
These parameters control CPU usage by container.
- --cpuunits num
- CPU weight for a container. Argument is positive non-zero number, passed
to and used in the kernel fair scheduler. The larger the number is, the
more CPU time this container gets. Maximum value is 500000, minimal is 8.
Number is relative to weights of all the other running containers. If
cpuunits are not specified, default value of 1000 is used.
You can set CPU weight for CT0 (host system itself) as well
(use vzctl set 0 --cpuunits num). Usually, OpenVZ
initscript (/etc/init.d/vz) takes care of setting this.
- --cpulimit num[%]
- Limit of CPU usage for the container, in per cent. Note if the computer
has 2 CPUs, it has total of 200% CPU time. Default CPU limit is 0 (no CPU
limit).
- --cpus num
- sets number of CPUs available in the container.
- Memory output parameters
-
This parameter control output of /proc/meminfo inside a
container
- --meminfo none
- No /proc/meminfo virtualization (the same as on host system).
- --meminfo mode:value
- Configure total memory output in a container. Reported free memory is
evaluated accordingly to the mode being set.
You can use the following modes for mode:
pages:value - sets total memory in pages
privvmpages:value - sets total memory as privvmpages *
value
Default is privvmpages:1.
- Iptables control parameters
- --iptables name
- Restrict access to iptables modules inside a container (by default all
iptables modules that are loaded in the host system are accessible inside
a container).
You can use the following values for name:
iptable_filter, iptable_mangle, ipt_limit,
ipt_multiport, ipt_tos, ipt_TOS, ipt_REJECT,
ipt_TCPMSS, ipt_tcpmss, ipt_ttl, ipt_LOG,
ipt_length, ip_conntrack, ip_conntrack_ftp,
ip_conntrack_irc, ipt_conntrack, ipt_state,
ipt_helper, iptable_nat, ip_nat_ftp,
ip_nat_irc, ipt_REDIRECT, xt_mac,
ipt_owner.
- Network devices control parameters
- --netdev_add name
- move network device from the host system to a specified container
- --netdev_del name
- delete network device from a specified container
- Disk quota parameters
- --diskspace num[:num]
- sets soft and hard disk quotas, in blocks. First parameter is soft quota,
second is hard quota. One block is currently equal to 1Kb. Also suffixes
G, M, K can be specified (see Resource limits
section for more info).
- --diskinodes num[:num]
- sets soft and hard disk quotas, in i-nodes. First parameter is soft quota,
second is hard quota.
- --quotatime seconds
- sets soft overusage time limit for disk quota (also known as grace
period).
- --quotaugidlimit num
- sets maximum number of user/group IDs in a container for which disk quota
inside the container will be accounted. If this value is set to 0,
user and group quotas inside the container will not be accounted.
Note that if you have previously set value of this parameter
to 0, changing it while the container is running will not take
effect.
- Mount option
- --noatime yes|no
- Sets noatime flag (do not update inode access times) on file system.
- Capability option
- --capability capname:on|off
- Sets a capability for a container. Note that setting capability when the
container is running does not take immediate effect; restart the container
in order for the changes to take effect. Note a container has default set
of capabilities, thus any operation on capabilities is "logical
and" with the default capability mask.
You can use the following values for capname:
chown, dac_override, dac_read_search,
fowner, fsetid, kill, setgid, setuid,
setpcap, linux_immutable, net_bind_service,
net_broadcast, net_admin, net_raw, ipc_lock,
ipc_owner, sys_module, sys_rawio,
sys_chroot, sys_ptrace, sys_pacct,
sys_admin, sys_boot, sys_nice, sys_resource,
sys_time, sys_tty_config, mknod, lease,
setveid, ve_admin.
WARNING: setting some of those capabilities may have
far reaching security implications, so do not do it unless you know what
you are doing. Also note that setting setpcap:on for a container
will most probably lead to inability to start it.
- Device access management
- --devnodes device:r|w|rw|none
- Give the container an access (r - read only, w - write only,
rw - read/write, none - no access) to a device designated by
the special file /dev/device. Device file is created in a container
by vzctl.
- --devices
b|c:major:minor|all:[r|w|rw|none]
- Give the container an access to a block or character device
designated by its major and minor numbers. Device file have
to be created manually.
- Features management
- --features name:on|off
- Enable or disable a specific container feature. Known features are:
sysfs, nfs.
- Apply config
- --applyconfig name
- Read container parameters from the container sample configuration file
/etc/vz/conf/ve-name.conf-sample,
and apply them, if --save option specified save to the container config
file. The following parameters are not changed: HOSTNAME,
IP_ADDRESS, OSTEMPLATE, VE_ROOT, and
VE_PRIVATE.
- --applyconfig_map group
- Apply container config parameters selected by group. Now only name
argument is supported, to restore container name based on NAME variable in
container configuration file.
- I/O priority management
- --ioprio priority
- Assigns I/O priority to container. Priority range is 0-7.
The greater priority is, the more time for I/O activity container
has. By default each container has priority of 4.
Checkpointing is a feature of OpenVZ kernel which allows to save a complete
state of a running container, and to restore it later.
- chkpnt CTID [--dumpfile name]
- This command saves a complete state of a running container to a dump file,
and stops the container. If an option --dumpfile is not set,
default dump file name /vz/dump/Dump.CTID is used.
- restore CTID [--dumpfile name]
- This command restores a container from the dump file created by the
chkpnt command.
- create CTID [--ostemplate name]
[--config name] [--private path] [--root
path] [--ipadd addr] [--hostname
name]
- Creates a new container area. This operation should be done once, before
the first start of the container.
If the --config option is specified, values from
example configuration file
/etc/vz/conf/ve-
name.conf-sample are put into the
container configuration file. If this container configuration file
already exists, it will be removed.
You can use --root path option to sets the path
to the mount point for the container root directory (default is
VE_ROOT specified in vz.conf(5) file). Argument can
contain string $VEID, which will be substituted with numeric CT
ID.
You can use --private path option to set the
path to directory in which all the files and directories specific to
this very container are stored (default is VE_PRIVATE specified
in vz.conf(5) file). Argument can contain string $VEID,
which will be substituted with the numeric CT ID.
You can use --ipadd addr option to assign an IP
address to a container. Note that this option can be used multiple
times.
You can use --hostname name option to set a host
name for a container.
- destroy
- Removes a container private area by deleting all files, directories and
the configuration file of this container.
- start [--wait] [--force]
- Mounts (if necessary) and starts a container. Unless --wait option
is specified, vzctl will return immediately; otherwise an attempt
to wait till the default runlevel is reached will be made by vzctl.
Specify --force if you want to start a container which
is disabled (see --disabled).
- stop
- Stops and unmounts a container.
- restart
- Restarts a container, i.e. stops it if it is running, and starts
again.
- status
- Shows a container status. This is a line with five words separated by
spaces. First word is literally CTID. Second word is the numeric
CT ID. Third word is showing whether this container exists or not,
it can be either exist or deleted. Fourth word is showing
the status of the container filesystem, it can be either mounted or
unmounted. Fifth word shows if the container is running, it can be
either running or down.
This command can also be usable from scripts.
- mount
- Mounts container private area.
- umount
- Unmounts container private area. Note that stop does umount
automatically.
- exec CTID command
- Executes command in a container. Environment variables are not set
inside the container. Signal handlers may differ from default settings. If
command is -, commands are read from stdin.
- exec2 CTID command
- The same as exec, but return code is that of command.
- runscript
- Run specified shell script in a container, if the container is not running
it will be started.
- enter
- Enters into a container. This option is a back-door for host root
only.
- --help
- Prints help message with a brief list of possible options.
- --version
- Prints vzctl version.
To create and start "basic" container with ID of 1000 using
fedora-core-5 OS template and IP address of 192.168.10.200:
vzctl create 1000 --ostemplate fedora-core-5 --config
vps.basic
vzctl set 1000 --ipadd 192.168.10.200 --save
vzctl start 1000
To set number of processes barrier/limit to 80/100, and PTY barrier/limit to
16/20 PTYs:
vzctl set 1000 --numproc 80:100 -t 16:20 --save
To execute command ls -la in this container:
vzctl exec 1000 /bin/ls -la
To execute command pipe ls -l / | sort in this container:
vzctl exec 1000 'ls -l / | sort'
To stop this container:
vzctl stop 1000
To permanently remove this container:
vzctl destroy 1000
/etc/vz/vz.conf
/etc/vz/conf/CTID.conf
/proc/vz/veinfo
/proc/vz/vzquota
/proc/user_beancounters
/proc/fairsched
vz.conf(5), vps.conf(5), vzquota(8),
Copyright (C) 2000-2008, Parallels, Inc. Licensed under GNU GPL.