DOCKERD(8)                                              Docker User Manuals                                              DOCKERD(8)

NAME
       dockerd - Enable daemon mode

SYNOPSIS
       dockerd  [--add-runtime[=[]]] [--allow-nondistributable-artifacts[=[]]] [--api-cors-header=[=API-CORS-HEADER]] [--authoriza‐
       tion-plugin[=[]]] [-b|--bridge[=BRIDGE]] [--bip[=BIP]] [--cgroup-parent[=[]]] [--config-file[=path]]  [--containerd[=SOCKET-
       PATH]]  [--data-root[=/var/lib/docker]]  [-D|--debug] [--default-cgroupns-mode[=host]] [--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]  [--http-proxy[""]] [--https-proxy[""]]
       [--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-re‐
       store[=false]] [--log-driver[=json-file]] [--log-opt[=map[]]]  [--mtu[=0]]  [--max-concurrent-downloads[=3]]  [--max-concur‐
       rent-uploads[=5]]      [--max-download-attempts[=5]]     [--no-proxy[""]]     [--node-generic-resources[=[]]]     [-p|--pid‐
       file[=/var/run/docker.pid]]  [--raw-logs]  [--registry-mirror[=[]]]  [-s|--storage-driver[=STORAGE-DRIVER]]  [--seccomp-pro‐
       file[=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[=de‐
       fault]] [--validate]

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 argu‐
       ment.

       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.

       --config-file="/etc/docker/daemon.json"
         Specifies the JSON file path to load the configuration from. Default is
         /etc/docker/daemon.json.

       --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-cgroupns-mode="host|private"
         Set the default cgroup namespace mode for newly created containers. The argument
         can either be host or private. If unset, this defaults to host on cgroup v1,
         or private on cgroup v2.

       --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="runtime"
         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=size
         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

       --http-proxy""
         Proxy URL for HTTP requests unless overridden by NoProxy.

       --https-proxy""
         Proxy URL for HTTPS requests unless overridden by NoProxy.

       --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 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. Default is 3.

       --max-concurrent-uploads=5
         Set the max concurrent uploads. Default is 5.

       --max-download-attempts=5
         Set the max download attempts for each pull. Default is 5.

       --no-proxy="""
         Comma-separated values specifying hosts that should be excluded from proxying.

       --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"
         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=://
         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=seconds
         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.

       --validate
         Validate daemon configuration and exit.

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 inef‐
       ficient.  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(8) to create a
       thin pool; for more information, see lvmthin(7).  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 in‐
       clude: 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 dae‐
       mon 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 = dis‐
       abled]

       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 hap‐
       pens 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 de‐
       fault 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 depre‐
       cated.

   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  addi‐
       tional 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 discus‐
       sion 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 under‐
       lying 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 e.g. 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

Access authorization
       Docker's access authorization can be extended by authorization plugins that your organization can purchase  or  build  them‐
       selves.  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 avail‐
       able to you.

       Once a plugin is installed, requests made to the daemon through the command line or Docker's Engine API are allowed  or  de‐
       nied  by  the  plugin.  If you have multiple plugins installed, each plugin, in order, must allow the request for it to com‐
       plete.

       For information about how to create an authorization plugin, see access  authorization  plugin  ⟨https://docs.docker.com/en‐
       gine/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 pre‐
       fix. 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  sys‐
       temd.  If  you  specify  systemd  and  it  is  not available, the system errors out. If you omit the native.cgroupdriver op‐
       tion,cgroupfs is used on cgroup v1 hosts, systemd is used on cgroup v2 hosts with systemd available.

       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  ⟨mailto:shishir.mahajan@redhat.com⟩  based  on
       docker.com source material and internal work.

Docker Community                                           SEPTEMBER 2015                                                DOCKERD(8)