Provided by: docker.io_24.0.5-0ubuntu1~20.04.1_amd64 bug

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[=[]]]  [--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-restore[=false]] [--log-driver[=json-file]]
       [--log-opt[=map[]]]   [--mtu[=0]]   [--max-concurrent-downloads[=3]]    [--max-concurrent-
       uploads[=5]]      [--max-download-attempts[=5]]      [--no-proxy[""]]     [--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]] [--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 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.

       --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 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(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  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  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 LevelValue--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 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  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.commailto:shishir.mahajan@redhat.com⟩ based on docker.com source material and internal work.