DOCKER(8) SEPTEMBER 2015 DOCKER(8)
NAME
dockerd - Enable daemon mode
SYNOPSIS
dockerd [--add-runtime[=[]]] [--allow-nondistributable-artifacts[=[]]]
[--api-cors-header=[=API-CORS-HEADER]] [--authorization-plugin[=[]]]
[-b|--bridge[=BRIDGE]] [--bip[=BIP]] [--cgroup-parent[=[]]]
[--cluster-store[=[]]] [--cluster-advertise[=[]]]
[--cluster-store-opt[=map[]]] [--config-file[=/etc/docker/daemon.json]]
[--containerd[=SOCKET-PATH]] [--data-root[=/var/lib/docker]]
[-D|--debug] [--default-gateway[=DEFAULT-GATEWAY]]
[--default-gateway-v6[=DEFAULT-GATEWAY-V6]]
[--default-address-pool[=DEFAULT-ADDRESS-POOL]]
[--default-runtime[=runc]] [--default-ipc-mode=MODE]
[--default-shm-size[=64MiB]] [--default-ulimit[=[]]] [--dns[=[]]]
[--dns-opt[=[]]] [--dns-search[=[]]] [--exec-opt[=[]]]
[--exec-root[=/var/run/docker]] [--experimental[=false]]
[--fixed-cidr[=FIXED-CIDR]] [--fixed-cidr-v6[=FIXED-CIDR-V6]]
[-G|--group[=docker]] [-H|--host[=[]]] [--help] [--icc[=true]]
[--init[=false]] [--init-path[=""]] [--insecure-registry[=[]]]
[--ip[=0.0.0.0]] [--ip-forward[=true]] [--ip-masq[=true]]
[--iptables[=true]] [--ipv6] [--isolation[=default]]
[-l|--log-level[=info]] [--label[=[]]] [--live-restore[=false]]
[--log-driver[=json-file]] [--log-opt[=map[]]] [--mtu[=0]]
[--max-concurrent-downloads[=3]] [--max-concurrent-uploads[=5]]
[--node-generic-resources[=[]]] [-p|--pidfile[=/var/run/docker.pid]]
[--raw-logs] [--registry-mirror[=[]]]
[-s|--storage-driver[=STORAGE-DRIVER]]
[--seccomp-profile[=SECCOMP-PROFILE-PATH]] [--selinux-enabled]
[--shutdown-timeout[=15]] [--storage-opt[=[]]]
[--swarm-default-advertise-addr[=IP|INTERFACE]] [--tls]
[--tlscacert[= /.docker/ca.pem]] [--tlscert[= /.docker/cert.pem]]
[--tlskey[= /.docker/key.pem]] [--tlsverify] [--userland-proxy[=true]]
[--userland-proxy-path[=""]] [--userns-remap[=default]]
DESCRIPTION
dockerd is used for starting the Docker daemon (i.e., to command the
daemon to manage images, containers etc). So dockerd is a server, as a
daemon.
To run the Docker daemon you can specify dockerd. You can check the
daemon options using dockerd --help. Daemon options should be
specified after the dockerd keyword in the following format.
dockerd [OPTIONS]
OPTIONS
--add-runtime=[]
Runtimes can be registered with the daemon either via the
configuration file or using the --add-runtime command line argument.
The following is an example adding 2 runtimes via the configuration:
{
"default-runtime": "runc",
"runtimes": {
"runc": {
"path": "runc"
},
"custom": {
"path": "/usr/local/bin/my-runc-replacement",
"runtimeArgs": [
"--debug"
]
}
}
}
This is the same example via the command line:
$ sudo dockerd --add-runtime runc=runc --add-runtime custom=/usr/local/bin/my-runc-replacement
Note: defining runtime arguments via the command line is not supported.
--allow-nondistributable-artifacts=[]
Push nondistributable artifacts to the specified registries.
List can contain elements with CIDR notation to specify a whole subnet.
This option is useful when pushing images containing nondistributable
artifacts to a registry on an air-gapped network so hosts on that
network can
pull the images without connecting to another server.
Warning: Nondistributable artifacts typically have restrictions on how
and where they can be distributed and shared. Only use this feature
to push
artifacts to private registries and ensure that you are in compliance
with
any terms that cover redistributing nondistributable artifacts.
--api-cors-header=""
Set CORS headers in the Engine API. Default is cors disabled. Give
urls like
" <http://foo>, <http://bar>, ...". Give "*" to allow all.
--authorization-plugin=""
Set authorization plugins to load
-b, --bridge=""
Attach containers to a pre-existing network bridge; use 'none' to
disable
container networking
--bip=""
Use the provided CIDR notation address for the dynamically created
bridge
(docker0); Mutually exclusive of -b
--cgroup-parent=""
Set parent cgroup for all containers. Default is "/docker" for fs
cgroup
driver and "system.slice" for systemd cgroup driver.
--cluster-store=""
URL of the distributed storage backend
--cluster-advertise=""
Specifies the 'host:port' or interface:port combination that this
particular daemon instance should use when advertising itself to the
cluster.
The daemon is reached through this value.
--cluster-store-opt=""
Specifies options for the Key/Value store.
--config-file="/etc/docker/daemon.json"
Specifies the JSON file path to load the configuration from.
--containerd=""
Path to containerd socket.
--data-root=""
Path to the directory used to store persisted Docker data such as
configuration for resources, swarm cluster state, and filesystem data
for
images, containers, and local volumes. Default is /var/lib/docker.
-D, --debug=true|false
Enable debug mode. Default is false.
--default-gateway=""
IPv4 address of the container default gateway; this address must be
part of
the bridge subnet (which is defined by -b or --bip)
--default-gateway-v6=""
IPv6 address of the container default gateway
--default-address-pool=""
Default address pool from which IPAM driver selects a subnet for the
networks.
Example: base=172.30.0.0/16,size=24 will set the default
address pools for the selected scope networks to
{172.30.[0-255].0/24}
--default-runtime="runc"
Set default runtime if there're more than one specified by
--add-runtime.
--default-ipc-mode="private|shareable"
Set the default IPC mode for newly created containers. The argument
can either be private or shareable.
--default-shm-size=64MiB
Set the daemon-wide default shm size for containers. Default is
64MiB.
--default-ulimit=[]
Default ulimits for containers.
--dns=""
Force Docker to use specific DNS servers
--dns-opt=""
DNS options to use.
--dns-search=[]
DNS search domains to use.
--exec-opt=[]
Set runtime execution options. See RUNTIME EXECUTION OPTIONS.
--exec-root=""
Path to use as the root of the Docker execution state files. Default
is
/var/run/docker.
--experimental=""
Enable the daemon experimental features.
--fixed-cidr=""
IPv4 subnet for fixed IPs (e.g., 10.20.0.0/16); this subnet must be
nested in
the bridge subnet (which is defined by -b or --bip).
--fixed-cidr-v6=""
IPv6 subnet for global IPv6 addresses (e.g., 2a00:1450::/64)
-G, --group=""
Group to assign the unix socket specified by -H when running in
daemon mode.
use '' (the empty string) to disable setting of a group. Default is
docker.
-H, --host=[unix:///var/run/docker.sock]: tcp://[host:port] to bind or
unix://[/path/to/socket] to use.
The socket(s) to bind to in daemon mode specified using one or more
tcp://host:port, unix:///path/to/socket, fd://* or fd://socketfd.
--help
Print usage statement
--icc=true|false
Allow unrestricted inter-container and Docker daemon host
communication. If
disabled, containers can still be linked together using the --link
option
(see docker-run(1)). Default is true.
--init
Run an init process inside containers for signal forwarding and
process
reaping.
--init-path
Path to the docker-init binary.
--insecure-registry=[]
Enable insecure registry communication, i.e., enable un-encrypted
and/or
untrusted communication.
List of insecure registries can contain an element with CIDR notation
to
specify a whole subnet. Insecure registries accept HTTP and/or accept
HTTPS
with certificates from unknown CAs.
Enabling --insecure-registry is useful when running a local registry.
However, because its use creates security vulnerabilities it should
ONLY be
enabled for testing purposes. For increased security, users should
add their
CA to their system's list of trusted CAs instead of using
--insecure-registry.
--ip=""
Default IP address to use when binding container ports. Default is
0.0.0.0.
--ip-forward=true|false
Enables IP forwarding on the Docker host. The default is true. This
flag
interacts with the IP forwarding setting on your host system's
kernel. If
your system has IP forwarding disabled, this setting enables it. If
your
system has IP forwarding enabled, setting this flag to
--ip-forward=false
has no effect.
This setting will also enable IPv6 forwarding if you have both
--ip-forward=true and --fixed-cidr-v6 set. Note that this may reject
Router Advertisements and interfere with the host's existing IPv6
configuration. For more information, please consult the documentation
about
"Advanced Networking - IPv6".
--ip-masq=true|false
Enable IP masquerading for bridge's IP range. Default is true.
--iptables=true|false
Enable Docker's addition of iptables rules. Default is true.
--ipv6=true|false
Enable IPv6 support. Default is false. Docker will create an
IPv6-enabled
bridge with address fe80::1 which will allow you to create
IPv6-enabled
containers. Use together with --fixed-cidr-v6 to provide globally
routable
IPv6 addresses. IPv6 forwarding will be enabled if not used with
--ip-forward=false. This may collide with your host's current IPv6
settings. For more information please consult the documentation about
"Advanced Networking - IPv6".
--isolation="default"
Isolation specifies the type of isolation technology used by
containers.
Note that the default on Windows server is process, and the default
on
Windows client is hyperv. Linux only supports default.
-l, --log-level="debug|info|warn|error|fatal"
Set the logging level. Default is info.
--label="[]"
Set key=value labels to the daemon (displayed in docker info)
--live-restore=false
Enable live restore of running containers when the daemon starts so
that they
are not restarted. This option is applicable only for docker daemon
running
on Linux host.
--log-driver="json-file|syslog|journald|gelf|fluentd|awslogs|splunk|etwlogs|gcplogs|none"
Default driver for container logs. Default is json-file.
Warning: docker logs command works only for json-file logging driver.
--log-opt=[]
Logging driver specific options.
--mtu=0
Set the containers network mtu. Default is 0.
--max-concurrent-downloads=3
Set the max concurrent downloads for each pull. Default is 3.
--max-concurrent-uploads=5
Set the max concurrent uploads for each push. Default is 5.
--node-generic-resources=[]
Advertise user-defined resource. Default is [].
Use this if your swarm cluster has some nodes with custom
resources (e.g: NVIDIA GPU, SSD, ...) and you need your services to
land on
nodes advertising these resources.
Usage example: --node-generic-resources "NVIDIA-GPU=UUID1"
--node-generic-resources "NVIDIA-GPU=UUID2"
-p, --pidfile=""
Path to use for daemon PID file. Default is /var/run/docker.pid
--raw-logs
Output daemon logs in full timestamp format without ANSI coloring. If
this
flag is not set, the daemon outputs condensed, colorized logs if a
terminal
is detected, or full ("raw") output otherwise.
--registry-mirror=<scheme>://<host>
Prepend a registry mirror to be used for image pulls. May be
specified
multiple times.
-s, --storage-driver=""
Force the Docker runtime to use a specific storage driver.
--seccomp-profile=""
Path to seccomp profile.
--selinux-enabled=true|false
Enable selinux support. Default is false.
--shutdown-timeout=15
Set the shutdown timeout value in seconds. Default is 15.
--storage-opt=[]
Set storage driver options. See STORAGE DRIVER OPTIONS.
--swarm-default-advertise-addr=IP|INTERFACE
Set default address or interface for swarm to advertise as its
externally-reachable address to other cluster members. This can be a
hostname, an IP address, or an interface such as eth0. A port cannot
be
specified with this option.
--tls=true|false
Use TLS; implied by --tlsverify. Default is false.
--tlscacert= /.docker/ca.pem
Trust certs signed only by this CA.
--tlscert= /.docker/cert.pem
Path to TLS certificate file.
--tlskey= /.docker/key.pem
Path to TLS key file.
--tlsverify=true|false
Use TLS and verify the remote (daemon: verify client, client: verify
daemon).
Default is false.
--userland-proxy=true|false
Rely on a userland proxy implementation for inter-container and
outside-to-container loopback communications. Default is true.
--userland-proxy-path=""
Path to the userland proxy binary.
--userns-remap=default|uid:gid|user:group|user|uid
Enable user namespaces for containers on the daemon. Specifying
"default"
will cause a new user and group to be created to handle UID and GID
range
remapping for the user namespace mappings used for contained
processes.
Specifying a user (or uid) and optionally a group (or gid) will cause
the
daemon to lookup the user and group's subordinate ID ranges for use
as the
user namespace mappings for contained processes.
STORAGE DRIVER OPTIONS
Docker uses storage backends (known as "graphdrivers" in the Docker
internals) to create writable containers from images. Many of these
backends use operating system level technologies and can be configured.
Specify options to the storage backend with --storage-opt flags. The
backends that currently take options are devicemapper, zfs and btrfs.
Options for devicemapper are prefixed with dm, options for zfs start
with zfs and options for btrfs start with btrfs.
Specifically for devicemapper, the default is a "loopback" model which
requires no pre-configuration, but is extremely inefficient. Do not
use it in production.
To make the best use of Docker with the devicemapper backend, you must
have a recent version of LVM. Use lvm to create a thin pool; for more
information see man lvmthin. Then, use --storage-opt dm.thinpooldev to
tell the Docker engine to use that pool for allocating images and
container snapshots.
Devicemapper options
dm.thinpooldev
Specifies a custom block storage device to use for the thin pool.
If using a block device for device mapper storage, it is best to use
lvm to create and manage the thin-pool volume. This volume is then
handed to Docker to exclusively create snapshot volumes needed for
images and containers.
Managing the thin-pool outside of Engine makes for the most
feature-rich method of having Docker utilize device mapper thin
provisioning as the backing storage for Docker containers. The
highlights of the lvm-based thin-pool management feature include:
automatic or interactive thin-pool resize support, dynamically changing
thin-pool features, automatic thinp metadata checking when lvm
activates the thin-pool, etc.
As a fallback if no thin pool is provided, loopback files are created.
Loopback is very slow, but can be used without any pre-configuration of
storage. It is strongly recommended that you do not use loopback in
production. Ensure your Engine daemon has a --storage-opt
dm.thinpooldev argument provided.
Example use:
$ dockerd \
--storage-opt dm.thinpooldev=/dev/mapper/thin-pool
dm.directlvm_device
As an alternative to manually creating a thin pool as above, Docker can
automatically configure a block device for you.
Example use:
$ dockerd \
--storage-opt dm.directlvm_device=/dev/xvdf
dm.thinp_percent
Sets the percentage of passed in block device to use for storage.
Example:
$ sudo dockerd \
--storage-opt dm.thinp_percent=95
dm.thinp_metapercent
Sets the percentage of the passed in block device to use for metadata
storage.
Example:
$ sudo dockerd \
--storage-opt dm.thinp_metapercent=1
dm.thinp_autoextend_threshold
Sets the value of the percentage of space used before lvm attempts to
autoextend the available space [100 = disabled]
Example:
$ sudo dockerd \
--storage-opt dm.thinp_autoextend_threshold=80
dm.thinp_autoextend_percent
Sets the value percentage value to increase the thin pool by when lvm
attempts to autoextend the available space [100 = disabled]
Example:
$ sudo dockerd \
--storage-opt dm.thinp_autoextend_percent=20
dm.basesize
Specifies the size to use when creating the base device, which limits
the size of images and containers. The default value is 10G. Note, thin
devices are inherently "sparse", so a 10G device which is mostly empty
doesn't use 10 GB of space on the pool. However, the filesystem will
use more space for base images the larger the device is.
The base device size can be increased at daemon restart which will
allow all future images and containers (based on those new images) to
be of the new base device size.
Example use: dockerd --storage-opt dm.basesize=50G
This will increase the base device size to 50G. The Docker daemon will
throw an error if existing base device size is larger than 50G. A user
can use this option to expand the base device size however shrinking is
not permitted.
This value affects the system-wide "base" empty filesystem that may
already be initialized and inherited by pulled images. Typically, a
change to this value requires additional steps to take effect:
$ sudo service docker stop
$ sudo rm -rf /var/lib/docker
$ sudo service docker start
Example use: dockerd --storage-opt dm.basesize=20G
dm.fs
Specifies the filesystem type to use for the base device. The supported
options are ext4 and xfs. The default is ext4.
Example use: dockerd --storage-opt dm.fs=xfs
dm.mkfsarg
Specifies extra mkfs arguments to be used when creating the base
device.
Example use: dockerd --storage-opt "dm.mkfsarg=-O ^has_journal"
dm.mountopt
Specifies extra mount options used when mounting the thin devices.
Example use: dockerd --storage-opt dm.mountopt=nodiscard
dm.use_deferred_removal
Enables use of deferred device removal if libdm and the kernel driver
support the mechanism.
Deferred device removal means that if device is busy when devices are
being removed/deactivated, then a deferred removal is scheduled on
device. And devices automatically go away when last user of the device
exits.
For example, when a container exits, its associated thin device is
removed. If that device has leaked into some other mount namespace and
can't be removed, the container exit still succeeds and this option
causes the system to schedule the device for deferred removal. It does
not wait in a loop trying to remove a busy device.
Example use: dockerd --storage-opt dm.use_deferred_removal=true
dm.use_deferred_deletion
Enables use of deferred device deletion for thin pool devices. By
default, thin pool device deletion is synchronous. Before a container
is deleted, the Docker daemon removes any associated devices. If the
storage driver can not remove a device, the container deletion fails
and daemon returns.
Error deleting container: Error response from daemon: Cannot destroy
container
To avoid this failure, enable both deferred device deletion and
deferred device removal on the daemon.
dockerd --storage-opt dm.use_deferred_deletion=true --storage-opt
dm.use_deferred_removal=true
With these two options enabled, if a device is busy when the driver is
deleting a container, the driver marks the device as deleted. Later,
when the device isn't in use, the driver deletes it.
In general it should be safe to enable this option by default. It will
help when unintentional leaking of mount point happens across multiple
mount namespaces.
dm.loopdatasize
Note: This option configures devicemapper loopback, which should not be
used in production.
Specifies the size to use when creating the loopback file for the
"data" device which is used for the thin pool. The default size is
100G. The file is sparse, so it will not initially take up this much
space.
Example use: dockerd --storage-opt dm.loopdatasize=200G
dm.loopmetadatasize
Note: This option configures devicemapper loopback, which should not be
used in production.
Specifies the size to use when creating the loopback file for the
"metadata" device which is used for the thin pool. The default size is
2G. The file is sparse, so it will not initially take up this much
space.
Example use: dockerd --storage-opt dm.loopmetadatasize=4G
dm.datadev
(Deprecated, use dm.thinpooldev)
Specifies a custom blockdevice to use for data for a Docker-managed
thin pool. It is better to use dm.thinpooldev - see the documentation
for it above for discussion of the advantages.
dm.metadatadev
(Deprecated, use dm.thinpooldev)
Specifies a custom blockdevice to use for metadata for a Docker-managed
thin pool. See dm.datadev for why this is deprecated.
dm.blocksize
Specifies a custom blocksize to use for the thin pool. The default
blocksize is 64K.
Example use: dockerd --storage-opt dm.blocksize=512K
dm.blkdiscard
Enables or disables the use of blkdiscard when removing devicemapper
devices. This is disabled by default due to the additional latency,
but as a special case with loopback devices it will be enabled, in
order to re-sparsify the loopback file on image/container removal.
Disabling this on loopback can lead to much faster container removal
times, but it also prevents the space used in /var/lib/docker directory
from being returned to the system for other use when containers are
removed.
Example use: dockerd --storage-opt dm.blkdiscard=false
dm.override_udev_sync_check
By default, the devicemapper backend attempts to synchronize with the
udev device manager for the Linux kernel. This option allows disabling
that synchronization, to continue even though the configuration may be
buggy.
To view the udev sync support of a Docker daemon that is using the
devicemapper driver, run:
$ docker info
[...]
Udev Sync Supported: true
[...]
When udev sync support is true, then devicemapper and udev can
coordinate the activation and deactivation of devices for containers.
When udev sync support is false, a race condition occurs between the
devicemapper and udev during create and cleanup. The race condition
results in errors and failures. (For information on these failures, see
docker#4036 <https://github.com/docker/docker/issues/4036>)
To allow the docker daemon to start, regardless of whether udev sync is
false, set dm.override_udev_sync_check to true:
$ dockerd --storage-opt dm.override_udev_sync_check=true
When this value is true, the driver continues and simply warns you the
errors are happening.
Note: The ideal is to pursue a docker daemon and environment that does
support synchronizing with udev. For further discussion on this topic,
see docker#4036 <https://github.com/docker/docker/issues/4036>.
Otherwise, set this flag for migrating existing Docker daemons to a
daemon with a supported environment.
dm.min_free_space
Specifies the min free space percent in a thin pool require for new
device creation to succeed. This check applies to both free data space
as well as free metadata space. Valid values are from 0% - 99%. Value
0% disables free space checking logic. If user does not specify a value
for this option, the Engine uses a default value of 10%.
Whenever a new a thin pool device is created (during docker pull or
during container creation), the Engine checks if the minimum free space
is available. If the space is unavailable, then device creation fails
and any relevant docker operation fails.
To recover from this error, you must create more free space in the thin
pool to recover from the error. You can create free space by deleting
some images and containers from tge thin pool. You can also add more
storage to the thin pool.
To add more space to an LVM (logical volume management) thin pool, just
add more storage to the group container thin pool; this should
automatically resolve any errors. If your configuration uses loop
devices, then stop the Engine daemon, grow the size of loop files and
restart the daemon to resolve the issue.
Example use:: dockerd --storage-opt dm.min_free_space=10%
dm.xfs_nospace_max_retries
Specifies the maximum number of retries XFS should attempt to complete
IO when ENOSPC (no space) error is returned by underlying storage
device.
By default XFS retries infinitely for IO to finish and this can result
in unkillable process. To change this behavior one can set
xfs_nospace_max_retries to say 0 and XFS will not retry IO after
getting ENOSPC and will shutdown filesystem.
Example use:
$ sudo dockerd --storage-opt dm.xfs_nospace_max_retries=0
dm.libdm_log_level
Specifies the maxmimum libdm log level that will be forwarded to the
dockerd log (as specified by --log-level). This option is primarily
intended for debugging problems involving libdm. Using values other
than the defaults may cause false-positive warnings to be logged.
Values specified must fall within the range of valid libdm log levels.
At the time of writing, the following is the list of libdm log levels
as well as their corresponding levels when output by dockerd.
+------------+-------+-------------+
|libdm Level | Value | --log-level |
+------------+-------+-------------+
|_LOG_FATAL | 2 | error |
+------------+-------+-------------+
|_LOG_ERR | 3 | error |
+------------+-------+-------------+
|_LOG_WARN | 4 | warn |
+------------+-------+-------------+
|_LOG_NOTICE | 5 | info |
+------------+-------+-------------+
|_LOG_INFO | 6 | info |
+------------+-------+-------------+
|_LOG_DEBUG | 7 | debug |
+------------+-------+-------------+
Example use:
$ sudo dockerd \
--log-level debug \
--storage-opt dm.libdm_log_level=7
ZFS options
zfs.fsname
Set zfs filesystem under which docker will create its own datasets. By
default docker will pick up the zfs filesystem where docker graph
(/var/lib/docker) is located.
Example use: dockerd -s zfs --storage-opt zfs.fsname=zroot/docker
Btrfs options
btrfs.min_space
Specifies the minimum size to use when creating the subvolume which is
used for containers. If user uses disk quota for btrfs when creating or
running a container with --storage-opt size option, docker should
ensure the size cannot be smaller than btrfs.min_space.
Example use: docker daemon -s btrfs --storage-opt btrfs.min_space=10G
CLUSTER STORE OPTIONS
The daemon uses libkv to advertise the node within the cluster. Some
Key/Value backends support mutual TLS, and the client TLS settings used
by the daemon can be configured using the --cluster-store-opt flag,
specifying the paths to PEM encoded files.
kv.cacertfile
Specifies the path to a local file with PEM encoded CA certificates to
trust
kv.certfile
Specifies the path to a local file with a PEM encoded certificate.
This certificate is used as the client cert for communication with the
Key/Value store.
kv.keyfile
Specifies the path to a local file with a PEM encoded private key.
This private key is used as the client key for communication with the
Key/Value store.
Access authorization
Docker's access authorization can be extended by authorization plugins
that your organization can purchase or build themselves. You can
install one or more authorization plugins when you start the Docker
daemon using the --authorization-plugin=PLUGIN_ID option.
dockerd --authorization-plugin=plugin1 --authorization-plugin=plugin2,...
The PLUGIN_ID value is either the plugin's name or a path to its
specification file. The plugin's implementation determines whether you
can specify a name or path. Consult with your Docker administrator to
get information about the plugins available to you.
Once a plugin is installed, requests made to the daemon through the
command line or Docker's Engine API are allowed or denied by the
plugin. If you have multiple plugins installed, each plugin, in order,
must allow the request for it to complete.
For information about how to create an authorization plugin, see access
authorization plugin
<https://docs.docker.com/engine/extend/plugins_authorization/> section
in the Docker extend section of this documentation.
RUNTIME EXECUTION OPTIONS
You can configure the runtime using options specified with the
--exec-opt flag. All the flag's options have the native prefix. A
single native.cgroupdriver option is available.
The native.cgroupdriver option specifies the management of the
container's cgroups. You can only specify cgroupfs or systemd. If you
specify systemd and it is not available, the system errors out. If you
omit the native.cgroupdriver option,cgroupfs is used.
This example sets the cgroupdriver to systemd:
$ sudo dockerd --exec-opt native.cgroupdriver=systemd
Setting this option applies to all containers the daemon launches.
HISTORY
Sept 2015, Originally compiled by Shishir Mahajan
<shishir.mahajan@redhat.com> based on docker.com source material and
internal work.
Shishir Mahajan Docker User Manuals DOCKER(8)