% DOCKER(1) Docker User Manuals % William Henry % APRIL 2014
docker - Docker image and container command line interface
docker [OPTIONS] COMMAND [arg...]
docker has two distinct functions. It is used for starting the Docker daemon and to run the CLI (i.e., to command the daemon to manage images, containers etc.) So docker is both a server, as a daemon, and a client to the daemon, through the CLI.
To run the Docker daemon you do not specify any of the commands listed below but must specify the -d option. The other options listed below are for the daemon only.
The Docker CLI has over 30 commands. The commands are listed below and each has its own man page which explain usage and arguments.
To see the man page for a command run man docker .
-h, --help Print usage statement
--api-cors-header="" Set CORS headers in the remote API. Default is cors disabled. Give urls like “http://foo, http://bar, ...”. Give “*” to allow all.
-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
-D, --debug=true|false Enable debug mode. Default is false.
-d, --daemon=true|false Enable daemon 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
--dns="" Force Docker to use specific DNS servers
-e, --exec-driver="" Force Docker to use specific exec driver. Default is native.
--exec-opt=[] Set exec driver options. See EXEC DRIVER OPTIONS.
--exec-root="" Path to use as the root of the Docker execdriver. Default is /var/run/docker.
--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.
-g, --graph="" Path to use as the root of the Docker runtime. Default is /var/lib/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.
--icc=true|false Allow unrestricted inter-container and Docker daemon host communication. If disabled, containers can still be linked together using --link option (see docker-run(1)). Default is true.
--ip="" Default IP address to use when binding container ports. Default is 0.0.0.0.
--ip-forward=true|false Docker will enable IP forwarding. Default is true. If --fixed-cidr-v6 is set. IPv6 forwarding will be activated, too. 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”.
-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)
--log-driver=“json-file|syslog|journald|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=VALUE Set the containers network mtu. Default is 0.
-p, --pidfile="" Path to use for daemon PID file. Default is /var/run/docker.pid
--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.
--selinux-enabled=true|false Enable selinux support. Default is false. SELinux does not presently support the BTRFS storage driver.
--storage-opt=[] Set storage driver options. See STORAGE DRIVER OPTIONS.
-tls=true|false Use TLS; implied by --tlsverify. Default is false.
-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.
-v, --version=true|false Print version information and quit. Default is false.
attach Attach to a running container See docker-attach(1) for full documentation on the attach command.
build Build an image from a Dockerfile See docker-build(1) for full documentation on the build command.
commit Create a new image from a container's changes See docker-commit(1) for full documentation on the commit command.
cp Copy files/folders from a container's filesystem to the host See docker-cp(1) for full documentation on the cp command.
create Create a new container See docker-create(1) for full documentation on the create command.
diff Inspect changes on a container's filesystem See docker-diff(1) for full documentation on the diff command.
events Get real time events from the server See docker-events(1) for full documentation on the events command.
exec Run a command in a running container See docker-exec(1) for full documentation on the exec command.
export Stream the contents of a container as a tar archive See docker-export(1) for full documentation on the export command.
history Show the history of an image See docker-history(1) for full documentation on the history command.
images List images See docker-images(1) for full documentation on the images command.
import Create a new filesystem image from the contents of a tarball See docker-import(1) for full documentation on the import command.
info Display system-wide information See docker-info(1) for full documentation on the info command.
inspect Return low-level information on a container or image See docker-inspect(1) for full documentation on the inspect command.
kill Kill a running container (which includes the wrapper process and everything inside it) See docker-kill(1) for full documentation on the kill command.
load Load an image from a tar archive See docker-load(1) for full documentation on the load command.
login Register or login to a Docker Registry See docker-login(1) for full documentation on the login command.
logout Log the user out of a Docker Registry See docker-logout(1) for full documentation on the logout command.
logs Fetch the logs of a container See docker-logs(1) for full documentation on the logs command.
pause Pause all processes within a container See docker-pause(1) for full documentation on the pause command.
port Lookup the public-facing port which is NAT-ed to PRIVATE_PORT See docker-port(1) for full documentation on the port command.
ps List containers See docker-ps(1) for full documentation on the ps command.
pull Pull an image or a repository from a Docker Registry See docker-pull(1) for full documentation on the pull command.
push Push an image or a repository to a Docker Registry See docker-push(1) for full documentation on the push command.
restart Restart a running container See docker-restart(1) for full documentation on the restart command.
rm Remove one or more containers See docker-rm(1) for full documentation on the rm command.
rmi Remove one or more images See docker-rmi(1) for full documentation on the rmi command.
run Run a command in a new container See docker-run(1) for full documentation on the run command.
save Save an image to a tar archive See docker-save(1) for full documentation on the save command.
search Search for an image in the Docker index See docker-search(1) for full documentation on the search command.
start Start a stopped container See docker-start(1) for full documentation on the start command.
stats Display a live stream of one or more containers' resource usage statistics See docker-stats(1) for full documentation on the stats command.
stop Stop a running container See docker-stop(1) for full documentation on the stop command.
tag Tag an image into a repository See docker-tag(1) for full documentation on the tag command.
top Lookup the running processes of a container See docker-top(1) for full documentation on the top command.
unpause Unpause all processes within a container See docker-unpause(1) for full documentation on the unpause command.
version Show the Docker version information See docker-version(1) for full documentation on the version command.
wait Block until a container stops, then print its exit code See docker-wait(1) for full documentation on the wait command.
Options to storage backend can be specified with --storage-opt flags. The only backend which currently takes options is devicemapper. Therefore use these flags with **-s=**devicemapper.
Here is the list of devicemapper options:
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 the empty case the larger the device is. Warning: This value affects the system-wide “base” empty filesystem that may already be initialized and inherited by pulled images.
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. Note that the file is sparse, so it will not initially take up this much space.
Specifies the size to use when creating the loopback file for the “metadadata” device which is used for the thin pool. The default size is 2G. Note that the file is sparse, so it will not initially take up this much space.
Specifies the filesystem type to use for the base device. The supported options are “ext4” and “xfs”. The default is “ext4”
Specifies extra mkfs arguments to be used when creating the base device.
Specifies extra mount options used when mounting the thin devices.
Specifies a custom blockdevice to use for data for the thin pool.
If using a block device for device mapper storage, ideally both datadev and metadatadev should be specified to completely avoid using the loopback device.
Specifies a custom blockdevice to use for metadata for the thin pool.
For best performance the metadata should be on a different spindle than the data, or even better on an SSD.
If setting up a new metadata pool it is required to be valid. This can be achieved by zeroing the first 4k to indicate empty metadata, like this:
dd if=/dev/zero of=/dev/metadata_dev bs=4096 count=1
Specifies a custom blocksize to use for the thin pool. The default blocksize is 64K.
Enables or disables the use of blkdiscard when removing devicemapper devices. This is enabled by default (only) if using loopback devices and is required to resparsify the loopback file on image/container removal.
Disabling this on loopback can lead to much faster container removal times, but will prevent the space used in /var/lib/docker directory from being returned to the system for other use when containers are removed.
Launching docker daemon with devicemapper backend with particular block devices for data and metadata:
docker -d -s=devicemapper \ --storage-opt dm.datadev=/dev/vdb \ --storage-opt dm.metadatadev=/dev/vdc \ --storage-opt dm.basesize=20G
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 thedevicemapper and udev during create and cleanup. The race condition results in errors and failures. (For information on these failures, see docker#4036)
To allow the docker daemon to start, regardless of whether udev sync is false, set dm.override_udev_sync_check to true:
$ docker -d --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. Otherwise, set this flag for migrating existing Docker daemons to a daemon with a supported environment.
Use the --exec-opt flags to specify options to the exec-driver. The only driver that accepts this flag is the native (libcontainer) driver. As a result, you must also specify **-s=**native for this option to have effect. The following is the only native option:
Specifies the management of the container's cgroups. You can specify cgroupfs or systemd. If you specify systemd and it is not available, the system uses cgroupfs.
For specific client examples please see the man page for the specific Docker command. For example:
man docker-run
April 2014, Originally compiled by William Henry (whenry at redhat dot com) based on docker.com source material and internal work.