Ubuntu Manpage: ovs-ctl - OVS startup helper script

Provided by: openvswitch-switch_2.9.8-0ubuntu0.18.04.5_amd64

NAME

       ovs-ctl - OVS startup helper script

SYNOPSIS

       ovs-ctl --system-id=random|uuid [options] start
       ovs-ctl stop
       ovs-ctl --system-id=random|uuid [options] restart
       ovs-ctl status
       ovs-ctl version
       ovs-ctl [options] load-kmod
       ovs-ctl --system-id=random|uuid [options] force-reload-kmod
       ovs-ctl [--protocol=protocol] [--sport=sport] [--dport=dport] enable-protocol
       ovs-ctl delete-transient-ports
       ovs-ctl help | -h | --help
       ovs-ctl --version

DESCRIPTION

       The  ovs-ctl  program starts, stops, and checks the status of Open vSwitch daemons.  It is
       not meant to be invoked directly by system administrators but to be called  internally  by
       system startup scripts.

       Each of ovs-ctl's commands is described separately below.

The ``start'' command

The start command starts Open vSwitch. It performs the following tasks:

1. Loads the Open vSwitch kernel module. If this fails, and the Linux bridge module
is loaded but no bridges exist, it tries to unload the bridge module and tries
loading the Open vSwitch kernel module again. (This is because the Open vSwitch
kernel module cannot coexist with the Linux bridge module before 2.6.37.)

The start command skips the following steps if ovsdb-server is already running:

2. If the Open vSwitch database file does not exist, it creates it. If the database
does exist, but it has an obsolete version, it upgrades it to the latest schema.

3. Starts ovsdb-server, unless the --no-ovsdb-server command option is given.

4. Initializes a few values inside the database.

5. If the --delete-bridges option was used, deletes all of the bridges from the
database.

6. If the --delete-transient-ports option was used, deletes all ports that have
other_config:transient set to true.

The start command skips the following step if ovs-vswitchd is already running, or if the
--no-ovs-vswitchd command option is given:

7. Starts ovs-vswitchd.

Options
Several command-line options influence the start command's behavior. Some form of the
following option should ordinarily be specified:

--system-id=uuid
--system-id=random
This specifies a unique system identifier to store into external-ids:system-id in
the database's Open_vSwitch table. Remote managers that talk to the Open vSwitch
database server over network protocols use this value to identify and distinguish
Open vSwitch instances, so it should be unique (at least) within OVS instances that
will connect to a single controller.

When random is specified, ovs-ctl will generate a random ID that persists from one
run to another (stored in a file). When another string is specified ovs-ctl uses
it literally.

The following options should be specified if the defaults are not suitable:

--system-type=type
--system-version=version
Sets the value to store in the system-type and system-version columns,
respectively, in the database's Open_vSwitch table. Remote managers may use these
values to determine the kind of system to which they are connected (primarily for
display to human administrators).

When not specified, ovs-ctl uses values from the optional system-type.conf and
system-version.conf files(see section FILES) or it uses the lsb_release program, if
present, to provide reasonable defaults.

The following options are also likely to be useful:

--external-id="name=value"
Sets external-ids:name to value in the database's Open_vSwitch table. Specifying
this option multiple times adds multiple key-value pairs.

--delete-bridges
Ordinarily Open vSwitch bridges persist from one system boot to the next, as long
as the database is preserved. Some environments instead expect to re-create all of
the bridges and other configuration state on every boot. This option supports
that, by deleting all Open vSwitch bridges after starting ovsdb-server but before
starting ovs-vswitchd.

--delete-transient-ports
Deletes all ports that have the other_config:transient value set to true. This is
important on certain environments where some ports are going to be recreated after
reboot, but other ports need to be persisted in the database.

--ovs-user=user[:group]
Ordinarily Open vSwitch daemons are started as the user invoking the ovs-ctl
command. Some system administrators would prefer to have the various daemons spawn
as different users in their environments. This option allows passing the --user
option to the ovsdb-server and ovs-vswitchd daemons, allowing them to change their
privilege levels.

The following options are less important:

--no-monitor
By default ovs-ctl passes --monitor to ovs-vswitchd and ovsdb-server, requesting
that it spawn a process monitor which will restart the daemon if it crashes. This
option suppresses that behavior.

--daemon-cwd=directory
Specifies the current working directory that the OVS daemons should run from. The
default is / (the root directory) if this option is not specified. (This option is
useful because most systems create core files in a process's current working
directory and because a file system that is in use as a process's current working
directory cannot be unmounted.)

--no-force-corefiles
By default, ovs-ctl enables core dumps for the OVS daemons. This option disables
that behavior.

--no-mlockall
By default ovs-ctl passes --mlockall to ovs-vswitchd, requesting that it lock all
of its virtual memory, preventing it from being paged to disk. This option
suppresses that behavior.

--no-self-confinement
Disable self-confinement for ovs-vswitchd and ovsdb-server daemons. This flag may
be used when, for example, OpenFlow controller creates its Unix Domain Socket
outside OVS run directory and OVS needs to connect to it. It is better to stick
with the default behavior and not to use this flag, unless:

• You have Open vSwitch running under SELinux or AppArmor Mandatory Access
Control that would prevent OVS from messing with sockets outside ordinary
OVS directories.

• You believe that relying on protocol handshakes (e.g. OpenFlow) is enough to
prevent OVS to adversely interact with other daemons running on your system.

• You don't have much worries of remote OVSDB exploits in the first place,
because, perhaps, OVSDB manager is running on the same host as OVS and share
similar attack vectors.

--ovsdb-server-priority=niceness
--ovs-vswitchd-priority=niceness
Sets the nice(1) level used for each daemon. All of them default to -10.

--ovsdb-server-wrapper=wrapper
--ovs-vswitchd-wrapper=wrapper
Configures the specified daemon to run under wrapper, which is one of the
following:

valgrind
Run the daemon under valgrind(1), if it is installed, logging to
daemon.valgrind.log.pid in the log directory.

strace Run the daemon under strace(1), if it is installed, logging to
daemon.strace.log.pid in the log directory.

glibc Enable GNU C library features designed to find memory errors.

By default, no wrapper is used.

Each of the wrappers can expose bugs in Open vSwitch that lead to incorrect
operation, including crashes. The valgrind and strace wrappers greatly slow daemon
operations so they should not be used in production. They also produce voluminous
logs that can quickly fill small disk partitions. The glibc wrapper is less
resource-intensive but still somewhat slows the daemons.

The following options control file locations. They should only be used if the default
locations cannot be used. See FILES, below, for more information.

--db-file=file
Overrides the file name for the OVS database.

--db-sock=socket
Overrides the file name for the Unix domain socket used to connect to ovsdb-server.

--db-schema=schema
Overrides the file name for the OVS database schema.

--extra-dbs=file
Adds file as an extra database for ovsdb-server to serve out. Multiple space-
separated file names may also be specified. file should begin with /; if it does
not, then it will be taken as relative to dbdir.

The ``stop'' command

       The stop command does not unload the Open vSwitch kernel modules. It  can  take  the  same
       --no-ovsdb-server and --no-ovs-vswitchd options as that of the start command.

       This command does nothing and finishes successfully if the OVS daemons aren't running.

The ``restart'' command

       The restart command performs a stop followed by a start command.  The command can take the
       same options as that of the start command. In addition, it  saves  and  restores  OpenFlow
       flows for each individual bridge.

The ``status'' command

       The  status  command  checks  whether  the  OVS  daemons ovs-vswitchd and ovsdb-server are
       running and prints messages with that information.  It exits with status 0 if the  daemons
       are running, 1 otherwise.

The ``version'' command

       The version command runs ovsdb-server --version and ovs-vswitchd --version.

The ``force-reload-kmod'' command

The force-reload-kmod command allows upgrading the Open vSwitch kernel module without
rebooting. It performs the following tasks:

1. Gets a list of OVS ``internal'' interfaces, that is, network devices implemented by
Open vSwitch. The most common examples of these are bridge ``local ports''.

2. Saves the OpenFlow flows of each bridge.

3. Stops the Open vSwitch daemons, as if by a call to ovs-ctl stop.

4. Saves the kernel configuration state of the OVS internal interfaces listed in step
1, including IP and IPv6 addresses and routing table entries.

5. Unloads the Open vSwitch kernel module (including the bridge compatibility module
if it is loaded).

6. Starts OVS back up, as if by a call to ovs-ctl start. This reloads the kernel
module, restarts the OVS daemons and finally restores the saved OpenFlow flows.

7. Restores the kernel configuration state that was saved in step 4.

8. Checks for daemons that may need to be restarted because they have packet sockets
that are listening on old instances of Open vSwitch kernel interfaces and, if it
finds any, prints a warning on stdout. DHCP is a common example: if the ISC DHCP
client is running on an OVS internal interface, then it will have to be restarted
after completing the above procedure. (It would be nice if ovs-ctl could restart
daemons automatically, but the details are far too specific to a particular
distribution and installation.)

force-kmod-reload internally stops and starts OVS, so it accepts all of the options
accepted by the start command except for the --no-ovs-vswitchd option.

The ``load-kmod'' command

       The load-kmod command loads the openvswitch kernel modules if they are not already loaded.
       This operation also occurs as part of the start command. The motivation for providing  the
       load-kmod  command  is to allow errors when loading modules to be handled separatetly from
       other errors that may occur when running the start command.

       By default the load-kmod command attempts to load the openvswitch kernel module.

The ``enable-protocol'' command

       The enable-protocol command checks for rules  related  to  a  specified  protocol  in  the
       system's  iptables(8)  configuration.   If there are no rules specifically related to that
       protocol, then it inserts a rule to accept the specified protocol.

       More specifically:

       •      If iptables is not installed or not enabled, this command  does  nothing,  assuming
              that lack of filtering means that the protocol is enabled.

       •      If  the  INPUT  chain  has  a  rule  that matches the specified protocol, then this
              command does nothing, assuming that whatever rule is installed reflects the  system
              administrator's decisions.

       •      Otherwise,  this  command  installs  a  rule  that accepts traffic of the specified
              protocol.

       This command normally completes successfully, even if it does nothing.  Only  the  failure
       of  an  attempt  to  insert a rule normally causes it to return an exit code other than 0.
       The following options control the protocol to be enabled:

       --protocol=protocol
              The name of the IP protocol to be enabled, such as gre or tcp.  The default is gre.

       --sport=sport
       --dport=dport
              TCP or UDP source or destination port to match.  These  are  optional  and  allowed
              only with --protocol=tcp or --protocol=udp.

The ``delete-transient-ports'' command

       Deletes all ports that have the other_config:transient value set to true.

The ``help'' command

       Prints a usage message and exits successfully.

OPTIONS

       In  addition  to  the  options  listed  for  each command above, these options control the
       behavior of several of ovs-ctl's commands.

       By default, ovs-ctl will control the  ovsdb-server,  and  the  ovs-vswitchd  daemons.  The
       following options restrict that control to exclude one or the other:

       --no-ovsdb-server
              Specifies  that the ovs-ctl commands start, stop, and restart should not modify the
              running status of ovsdb-server.

       --no-ovs-vswitchd
              Specifies that the ovs-ctl commands start, stop, and restart should not modify  the
              running  status  of  ovs-vswitchd.   It is an error to include this option with the
              force-reload-kmod command.

EXIT STATUS

       ovs-ctl exits with status 0 on success and nonzero  on  failure.   The  start  command  is
       considered to succeed if OVS is already started; the stop command is considered to succeed
       if OVS is already stopped.

ENVIRONMENT

       The following environment variables affect ovs-ctl:

       PATH   ovs-ctl does not hardcode the location  of  any  of  the  programs  that  it  runs.
              ovs-ctl  will  add  the sbindir and bindir that were specified at configure time to
              PATH, if they are not already present.

       OVS_LOGDIR
       OVS_RUNDIR
       OVS_DBDIR
       OVS_SYSCONFDIR
       OVS_PKGDATADIR
       OVS_BINDIR
       OVS_SBINDIR
              Setting one  of  these  variables  in  the  environment  overrides  the  respective
              configure  option,  both for ovs-ctl itself and for the other Open vSwitch programs
              that it runs.

FILES

       ovs-ctl uses the following files:

       ovs-lib
              Shell function library used internally by ovs-ctl.  It must  be  installed  in  the
              same directory as ovs-ctl.

       logdir/daemon.log
              Per-daemon logfiles.

       rundir/daemon.pid
              Per-daemon pidfiles to track whether a daemon is running and with what process ID.

       pkgdatadir/vswitch.ovsschema
              The  OVS  database  schema  used  to  initialize  the  database (use --db-schema to
              override this location).

       dbdir/conf.db
              The OVS database (use --db-file to override this location).

       rundir/openvswitch/db.sock
              The Unix  domain  socket  used  for  local  communication  with  ovsdb-server  (use
              --db-sock to override this location).

       sysconfdir/openvswitch/system-id.conf
              The persistent system UUID created and read by --system-id=random.

       sysconfdir/openvswitch/system-type.conf
       sysconfdir/openvswitch/system-version.conf
              The  system-type   and  system-version values stored in the database's Open_vSwitch
              table when not specified as a command-line option.

EXAMPLE

       The files debian/openvswitch-switch.init and xenserver/etc_init.d_openvswitch in the  Open
       vSwitch source distribution are good examples of how to use ovs-ctl.