Mục Lục

docker run

Create and run a new container from an image

Usage

$
 
docker run [
OPTIONS] IMAGE [
COMMAND] [ARG...]

Refer to the options section for an overview of available OPTIONS for this command.

Description

The docker run command first creates a writeable container layer over the
specified image, and then starts it using the specified command. That is,
docker run is equivalent to the API /containers/create then
/containers/(id)/start. A stopped container can be restarted with all its
previous changes intact using docker start. See docker ps -a to view a list
of all containers.

For information on connecting a container to a network, see the “Docker network overview”.

For example uses of this command, refer to the examples section below.

Options

Name, shorthand
Default
Description

--add-host

Add a custom host-to-IP mapping (host:ip)

--attach , -a

Attach to STDIN, STDOUT or STDERR

--blkio-weight

Block IO (relative weight), between 10 and 1000, or 0 to disable (default 0)

--blkio-weight-device

Block IO weight (relative device weight)

--cap-add

Add Linux capabilities

--cap-drop

Drop Linux capabilities

--cgroup-parent

Optional parent cgroup for the container

--cgroupns

API 1.41+

Cgroup namespace to use (host|private)
‘host’: Run the container in the Docker host’s cgroup namespace
‘private’: Run the container in its own private cgroup namespace
‘’: Use the cgroup namespace as configured by the
default-cgroupns-mode option on the daemon (default)

--cidfile

Write the container ID to the file

--cpu-count

CPU count (Windows only)

--cpu-percent

CPU percent (Windows only)

--cpu-period

Limit CPU CFS (Completely Fair Scheduler) period

--cpu-quota

Limit CPU CFS (Completely Fair Scheduler) quota

--cpu-rt-period

Limit CPU real-time period in microseconds

--cpu-rt-runtime

Limit CPU real-time runtime in microseconds

--cpu-shares , -c

CPU shares (relative weight)

--cpus

Number of CPUs

--cpuset-cpus

CPUs in which to allow execution (0-3, 0,1)

--cpuset-mems

MEMs in which to allow execution (0-3, 0,1)

--detach , -d

Run container in background and print container ID

--detach-keys

Override the key sequence for detaching a container

--device

Add a host device to the container

--device-cgroup-rule

Add a rule to the cgroup allowed devices list

--device-read-bps

Limit read rate (bytes per second) from a device

--device-read-iops

Limit read rate (IO per second) from a device

--device-write-bps

Limit write rate (bytes per second) to a device

--device-write-iops

Limit write rate (IO per second) to a device

--disable-content-trust
true
Skip image verification

--dns

Set custom DNS servers

--dns-option

Set DNS options

--dns-search

Set custom DNS search domains

--domainname

Container NIS domain name

--entrypoint

Overwrite the default ENTRYPOINT of the image

--env , -e

Set environment variables

--env-file

Read in a file of environment variables

--expose

Expose a port or a range of ports

--gpus

API 1.40+

GPU devices to add to the container (‘all’ to pass all GPUs)

--group-add

Add additional groups to join

--health-cmd

Command to run to check health

--health-interval

Time between running the check (ms|s|m|h) (default 0s)

--health-retries

Consecutive failures needed to report unhealthy

--health-start-period

Start period for the container to initialize before starting health-retries countdown (ms|s|m|h) (default 0s)

--health-timeout

Maximum time to allow one check to run (ms|s|m|h) (default 0s)

--help

Print usage

--hostname , -h

Container host name

--init

Run an init inside the container that forwards signals and reaps processes

--interactive , -i

Keep STDIN open even if not attached

--io-maxbandwidth

Maximum IO bandwidth limit for the system drive (Windows only)

--io-maxiops

Maximum IOps limit for the system drive (Windows only)

--ip

IPv4 address (e.g., 172.30.100.104)

--ip6

IPv6 address (e.g., 2001:db8::33)

--ipc

IPC mode to use

--isolation

Container isolation technology

--kernel-memory

Kernel memory limit

--label , -l

Set meta data on a container

--label-file

Read in a line delimited file of labels

--link

Add link to another container

--link-local-ip

Container IPv4/IPv6 link-local addresses

--log-driver

Logging driver for the container

--log-opt

Log driver options

--mac-address

Container MAC address (e.g., 92:d0:c6:0a:29:33)

--memory , -m

Memory limit

--memory-reservation

Memory soft limit

--memory-swap

Swap limit equal to memory plus swap: ‘-1’ to enable unlimited swap

--memory-swappiness
-1
Tune container memory swappiness (0 to 100)

--mount

Attach a filesystem mount to the container

--name

Assign a name to the container

--network

Connect a container to a network

--network-alias

Add network-scoped alias for the container

--no-healthcheck

Disable any container-specified HEALTHCHECK

--oom-kill-disable

Disable OOM Killer

--oom-score-adj

Tune host’s OOM preferences (-1000 to 1000)

--pid

PID namespace to use

--pids-limit

Tune container pids limit (set -1 for unlimited)

--platform

Set platform if server is multi-platform capable

--privileged

Give extended privileges to this container

--publish , -p

Publish a container’s port(s) to the host

--publish-all , -P

Publish all exposed ports to random ports

--pull
missing
Pull image before running (always, missing, never)

--quiet , -q

Suppress the pull output

--read-only

Mount the container’s root filesystem as read only

--restart
no
Restart policy to apply when a container exits

--rm

Automatically remove the container when it exits

--runtime

Runtime to use for this container

--security-opt

Security Options

--shm-size

Size of /dev/shm

--sig-proxy
true
Proxy received signals to the process

--stop-signal

Signal to stop the container

--stop-timeout

Timeout (in seconds) to stop a container

--storage-opt

Storage driver options for the container

--sysctl

Sysctl options

--tmpfs

Mount a tmpfs directory

--tty , -t

Allocate a pseudo-TTY

--ulimit

Ulimit options

--user , -u

Username or UID (format: <name|uid>[:<group|gid>])

--userns

User namespace to use

--uts

UTS namespace to use

--volume , -v

Bind mount a volume

--volume-driver

Optional volume driver for the container

--volumes-from

Mount volumes from the specified container(s)

--workdir , -w

Working directory inside the container

Examples

Assign name and allocate pseudo-TTY (–name, -it)

$
 
docker run --name
 test
 -it debian

root@d6c0fe130dba:/#
 
exit 13
$
 
echo
 $?
13
$
 
docker ps -a
 | grep test
d6c0fe130dba        debian:7            "/bin/bash"         26 seconds ago      Exited (13) 17 seconds ago                         test

This example runs a container named test using the debian:latest
image. The -it instructs Docker to allocate a pseudo-TTY connected to
the container’s stdin; creating an interactive bash shell in the container.
In the example, the bash shell is quit by entering
exit 13. This exit code is passed on to the caller of
docker run, and is recorded in the test container’s metadata.

Capture container ID (–cidfile)

$
 
docker run --cidfile
 /tmp/docker_test.cid ubuntu echo
 "test"

This will create a container and print test to the console. The cidfile
flag makes Docker attempt to create a new file and write the container ID to it.
If the file exists already, Docker will return an error. Docker will close this
file when docker run exits.

Full container capabilities (–privileged)

$
 
docker run -t
 -i
 --rm ubuntu bash
root@bc338942ef20:/#
 
mount -t tmpfs none /mnt
mount: permission denied

This will not work, because by default, most potentially dangerous kernel
capabilities are dropped; including cap_sys_admin (which is required to mount
filesystems). However, the --privileged flag will allow it to run:

$
 
docker run -t
 -i
 --privileged ubuntu bash
root@50e3f57e16e6:/#
 
mount -t tmpfs none /mnt
root@50e3f57e16e6:/#
 
df
 -h
Filesystem      Size  Used Avail Use% Mounted on
none            1.9G     0  1.9G   0% /mnt

The --privileged flag gives all capabilities to the container, and it also
lifts all the limitations enforced by the device cgroup controller. In other
words, the container can then do almost everything that the host can do. This
flag exists to allow special use-cases, like running Docker within Docker.

Set working directory (-w, –workdir)

$
 
docker  run -w
 /path/to/dir/ -i
 -t
  ubuntu pwd

The -w lets the command being executed inside directory given, here
/path/to/dir/. If the path does not exist it is created inside the container.

Set storage driver options per container (–storage-opt)

$
 
docker run -it
 --storage-opt
 size
=120G fedora /bin/bash

This (size) will allow to set the container filesystem size to 120G at creation time.
This option is only available for the devicemapper, btrfs, overlay2,
windowsfilter and zfs graph drivers.
For the devicemapper, btrfs, windowsfilter and zfs graph drivers,
user cannot pass a size less than the Default BaseFS Size.
For the overlay2 storage driver, the size option is only available if the
backing filesystem is xfs and mounted with the pquota mount option.
Under these conditions, user can pass any size less than the backing filesystem size.

Mount tmpfs (–tmpfs)

$
 
docker run -d
 --tmpfs
 /run:rw,noexec,nosuid,size=65536k my_image

The --tmpfs flag mounts an empty tmpfs into the container with the rw,
noexec, nosuid, size=65536k options.

Mount volume (-v, –read-only)

$
 
docker  run  -v
 `
pwd
`
:`
pwd
`
 -w
 `
pwd
`
 -i
 -t
  ubuntu pwd

The -v flag mounts the current working directory into the container. The -w
lets the command being executed inside the current working directory, by
changing into the directory to the value returned by pwd. So this
combination executes the command using the container, but inside the
current working directory.

$
 
docker run -v
 /doesnt/exist:/foo -w
 /foo -i
 -t ubuntu bash

When the host directory of a bind-mounted volume doesn’t exist, Docker
will automatically create this directory on the host for you. In the
example above, Docker will create the /doesnt/exist
folder before starting your container.

$
 
docker run --read-only
 -v
 /icanwrite busybox touch /icanwrite/here

Volumes can be used in combination with --read-only to control where
a container writes files. The --read-only flag mounts the container’s root
filesystem as read only prohibiting writes to locations other than the
specified volumes for the container.

$
 
docker run -t
 -i
 -v
 /var/run/docker.sock:/var/run/docker.sock -v /path/to/static-docker-binary:/usr/bin/docker busybox sh

By bind-mounting the Docker Unix socket and statically linked Docker
binary (refer to get the Linux binary),
you give the container the full access to create and manipulate the host’s
Docker daemon.

On Windows, the paths must be specified using Windows-style semantics.

PS
 
C:\
>
 
docker
 
run
 
-v
 
c:\foo:c:\dest
 
microsoft/nanoserver
 
cmd
 
/s
 
/c
 
type
 
c:\dest\somefile.txt

Contents
 
of
 
file


PS
 
C:\
>
 
docker
 
run
 
-v
 
c:\foo:d:
 
microsoft/nanoserver
 
cmd
 
/s
 
/c
 
type
 
d:\somefile.txt

Contents
 
of
 
file

The following examples will fail when using Windows-based containers, as the
destination of a volume or bind mount inside the container must be one of:
a non-existing or empty directory; or a drive other than C:. Further, the source
of a bind mount must be a local directory, not a file.

net
 
use
 
z:
 
\\remotemachine\share

docker
 
run
 
-v
 
z:\foo:c:\dest
 
...

docker
 
run
 
-v
 
\\uncpath\to\directory:c:\dest
 
...

docker
 
run
 
-v
 
c:\foo\somefile.txt:c:\dest
 
...

docker
 
run
 
-v
 
c:\foo:c:
 
...

docker
 
run
 
-v
 
c:\foo:c:\existing-directory-with-contents
 
...

For in-depth information about volumes, refer to manage data in containers

Add bind mounts or volumes using the –mount flag

The --mount flag allows you to mount volumes, host-directories and tmpfs
mounts in a container.

The --mount flag supports most options that are supported by the -v or the
--volume flag, but uses a different syntax. For in-depth information on the
--mount flag, and a comparison between --volume and --mount, refer to
Bind mounts.

Even though there is no plan to deprecate --volume, usage of --mount is recommended.

Examples:

$
 
docker run --read-only
 --mount
 type
=
volume,target=
/icanwrite busybox touch /icanwrite/here

$
 
docker run -t
 -i
 --mount
 type
=
bind
,src=
/data,dst=/data busybox sh

Publish or expose port (-p, –expose)

$
 
docker run -p 127.0.0.1:80:8080/tcp ubuntu bash

This binds port 8080 of the container to TCP port 80 on 127.0.0.1 of the host
machine. You can also specify udp and sctp ports.
The Docker User Guide
explains in detail how to manipulate ports in Docker.

Note that ports which are not bound to the host (i.e., -p 80:80 instead of
-p 127.0.0.1:80:80) will be accessible from the outside. This also applies if
you configured UFW to block this specific port, as Docker manages its
own iptables rules. Read more

$
 
docker run --expose 80 ubuntu bash

This exposes port 80 of the container without publishing the port to the host
system’s interfaces.

Set the pull policy (–pull)

Use the --pull flag to set the image pull policy when creating (and running)
the container.

The --pull flag can take one of these values:

Value
Description

missing (default)
Pull the image if it was not found in the image cache, or use the cached image otherwise.

never
Do not pull the image, even if it’s missing, and produce an error if the image does not exist in the image cache.

always
Always perform a pull before creating the container.

When creating (and running) a container from an image, the daemon checks if the
image exists in the local image cache. If the image is missing, an error is
returned to the CLI, allowing it to initiate a pull.

The default (missing) is to only pull the image if it is not present in the
daemon’s image cache. This default allows you to run images that only exist
locally (for example, images you built from a Dockerfile, but that have not
been pushed to a registry), and reduces networking.

The always option always initiates a pull before creating the container. This
option makes sure the image is up-to-date, and prevents you from using outdated
images, but may not be suitable in situations where you want to test a locally
built image before pushing (as pulling the image overwrites the existing image
in the image cache).

The never option disables (implicit) pulling images when creating containers,
and only uses images that are available in the image cache. If the specified
image is not found, an error is produced, and the container is not created.
This option is useful in situations where networking is not available, or to
prevent images from being pulled implicitly when creating containers.

The following example shows docker run with the --pull=never option set,
which produces en error as the image is missing in the image-cache:

$
 
docker run --pull
=never hello-world
docker: Error response from daemon: No such image: hello-world:latest.

Set environment variables (-e, –env, –env-file)

$
 
docker run -e
 MYVAR1 --env
 MYVAR2
=
foo --env-file ./env.list ubuntu bash

Use the -e, --env, and --env-file flags to set simple (non-array)
environment variables in the container you’re running, or overwrite variables
that are defined in the Dockerfile of the image you’re running.

You can define the variable and its value when running the container:

$
 
docker run --env
 VAR1
=
value1 --env
 VAR2
=
value2 ubuntu env
 | grep VAR
VAR1=value1
VAR2=value2

You can also use variables that you’ve exported to your local environment:

export VAR1=value1
export VAR2=value2

$
 
docker run --env
 VAR1 --env
 VAR2 ubuntu env
 | grep VAR
VAR1=value1
VAR2=value2

When running the command, the Docker CLI client checks the value the variable
has in your local environment and passes it to the container.
If no = is provided and that variable is not exported in your local
environment, the variable won’t be set in the container.

You can also load the environment variables from a file. This file should use
the syntax <variable>=value (which sets the variable to the given value) or
<variable> (which takes the value from the local environment), and # for comments.

$
 
cat env.list
#
 This is a comment
VAR1=value1
VAR2=value2
USER

$
 
docker run --env-file
 env.list ubuntu env
 | grep
 -E
 'VAR|USER'
VAR1=value1
VAR2=value2
USER=jonzeolla

Set metadata on container (-l, –label, –label-file)

A label is a key=value pair that applies metadata to a container. To label a container with two labels:

$
 
docker run -l
 my-label --label
 com.example.foo=bar ubuntu bash

The my-label key doesn’t specify a value so the label defaults to an empty
string (""). To add multiple labels, repeat the label flag (-l or --label).

The key=value must be unique to avoid overwriting the label value. If you
specify labels with identical keys but different values, each subsequent value
overwrites the previous. Docker uses the last key=value you supply.

Use the --label-file flag to load multiple labels from a file. Delimit each
label in the file with an EOL mark. The example below loads labels from a
labels file in the current directory:

$
 
docker run --label-file ./labels ubuntu bash

The label-file format is similar to the format for loading environment
variables. (Unlike environment variables, labels are not visible to processes
running inside a container.) The following example illustrates a label-file
format:

com.example.label1="a label"

#
 this is a comment
com.example.label2=another\ label
com.example.label3

You can load multiple label-files by supplying multiple --label-file flags.

For additional information on working with labels, see Labels – custom
metadata in Docker in
the Docker User Guide.

Connect a container to a network (–network)

When you start a container use the --network flag to connect it to a network.
The following commands create a network named my-net, and adds a busybox container
to the my-net network.

$
 docker network create my-net
$
 
docker run -itd
 --network
=my-net busybox

You can also choose the IP addresses for the container with --ip and --ip6
flags when you start the container on a user-defined network.

$
 
docker run -itd
 --network
=
my-net --ip
=10.10.9.75 busybox

If you want to add a running container to a network use the docker network connect subcommand.

You can connect multiple containers to the same network. Once connected, the
containers can communicate easily using only another container’s IP address
or name. For overlay networks or custom plugins that support multi-host
connectivity, containers connected to the same multi-host network but launched
from different Engines can also communicate in this way.

Note

The default bridge network only allow containers to communicate with each other using
internal IP addresses. User-created bridge networks provide DNS resolution between
containers using container names.

You can disconnect a container from a network using the docker network disconnect command.

Mount volumes from container (–volumes-from)

$
 
docker run --volumes-from
 777f7dc92da7 --volumes-from
 ba8c0c54f0f2:ro -i
 -t
 ubuntu pwd

The --volumes-from flag mounts all the defined volumes from the referenced
containers. Containers can be specified by repetitions of the --volumes-from
argument. The container ID may be optionally suffixed with :ro or :rw to
mount the volumes in read-only or read-write mode, respectively. By default,
the volumes are mounted in the same mode (read write or read only) as
the reference container.

Labeling systems like SELinux require that proper labels are placed on volume
content mounted into a container. Without a label, the security system might
prevent the processes running inside the container from using the content. By
default, Docker does not change the labels set by the OS.

To change the label in the container context, you can add either of two suffixes
:z or :Z to the volume mount. These suffixes tell Docker to relabel file
objects on the shared volumes. The z option tells Docker that two containers
share the volume content. As a result, Docker labels the content with a shared
content label. Shared volume labels allow all containers to read/write content.
The Z option tells Docker to label the content with a private unshared label.
Only the current container can use a private volume.

Attach to STDIN/STDOUT/STDERR (-a, –attach)

The --attach (or -a) flag tells docker run to bind to the container’s
STDIN, STDOUT or STDERR. This makes it possible to manipulate the output
and input as needed.

$
 
echo
 "test"
 | docker run -i
 -a
 stdin ubuntu cat -

This pipes data into a container and prints the container’s ID by attaching
only to the container’s STDIN.

$
 
docker run -a
 stderr ubuntu echo test

This isn’t going to print anything unless there’s an error because we’ve
only attached to the STDERR of the container. The container’s logs
still store what’s been written to STDERR and STDOUT.

$
 
cat 
somefile | docker run -i
 -a stdin mybuilder dobuild

This is a way of using --attach to pipe a build file into a container.
The container’s ID will be printed after the build is done and the build
logs could be retrieved using docker logs. This is
useful if you need to pipe a file or something else into a container and
retrieve the container’s ID once the container has finished running.

Add host device to container (–device)

$
 
docker run -it
 --rm
 \
    --device
=
/dev/sdc:/dev/xvdc \
    --device
=
/dev/sdd \
    --device
=
/dev/zero:/dev/foobar \
    ubuntu ls
 -l
 /dev/{
xvdc,sdd,foobar}

brw-rw---- 1 root disk 8, 2 Feb  9 16:05 /dev/xvdc
brw-rw---- 1 root disk 8, 3 Feb  9 16:05 /dev/sdd
crw-rw-rw- 1 root root 1, 5 Feb  9 16:05 /dev/foobar

It is often necessary to directly expose devices to a container. The --device
option enables that. For example, a specific block storage device or loop
device or audio device can be added to an otherwise unprivileged container
(without the --privileged flag) and have the application directly access it.

By default, the container will be able to read, write and mknod these devices.
This can be overridden using a third :rwm set of options to each --device
flag. If the container is running in privileged mode, then the permissions specified
will be ignored.

$
 
docker run --device
=
/dev/sda:/dev/xvdc --rm
 -it ubuntu fdisk  /dev/xvdc

Command (m for help): q
$
 
docker run --device
=
/dev/sda:/dev/xvdc:r --rm
 -it ubuntu fdisk  /dev/xvdc
You will not be able to write the partition table.

Command (m for help): q

$
 
docker run --device
=
/dev/sda:/dev/xvdc:rw --rm
 -it ubuntu fdisk  /dev/xvdc

Command (m for help): q

$
 
docker run --device
=
/dev/sda:/dev/xvdc:m --rm
 -it ubuntu fdisk  /dev/xvdc
fdisk: unable to open /dev/xvdc: Operation not permitted

Note

The --device option cannot be safely used with ephemeral devices. Block devices
that may be removed should not be added to untrusted containers with --device.

For Windows, the format of the string passed to the --device option is in
the form of --device=<IdType>/<Id>. Beginning with Windows Server 2019
and Windows 10 October 2018 Update, Windows only supports an IdType of
class and the Id as a device interface class
GUID.
Refer to the table defined in the Windows container
docs
for a list of container-supported device interface class GUIDs.

If this option is specified for a process-isolated Windows container, all
devices that implement the requested device interface class GUID are made
available in the container. For example, the command below makes all COM
ports on the host visible in the container.

PS
 
C:\
>
 
docker
 
run
 
--device
=
class
/86E0D1E0-8089-11D0-9CE4-08003E301F73
 
mcr.microsoft.com/windows/servercore:ltsc2019

Note

The --device option is only supported on process-isolated Windows containers,
and produces an error if the container isolation is hyperv.

Using dynamically created devices (–device-cgroup-rule)

Devices available to a container are assigned at creation time. The
assigned devices will both be added to the cgroup.allow file and
created into the container once it is run. This poses a problem when
a new device needs to be added to running container.

One of the solutions is to add a more permissive rule to a container
allowing it access to a wider range of devices. For example, supposing
our container needs access to a character device with major 42 and
any number of minor number (added as new devices appear), the
following rule would be added:

$
 
docker run -d
 --device-cgroup-rule
=
'c 42:* rmw'
 -name my-container my-image

Then, a user could ask udev to execute a script that would docker exec my-container mknod newDevX c 42 <minor>
the required device when it is added.

Note: initially present devices still need to be explicitly added to the
docker run / docker create command.

Access an NVIDIA GPU

The --gpus flag allows you to access NVIDIA GPU resources. First you need to
install nvidia-container-runtime.
Visit Specify a container’s resources
for more information.

To use --gpus, specify which GPUs (or all) to use. If no value is provided, all
available GPUs are used. The example below exposes all available GPUs.

$
 
docker run -it
 --rm
 --gpus all ubuntu nvidia-smi

Use the device option to specify GPUs. The example below exposes a specific
GPU.

$
 
docker run -it
 --rm
 --gpus
 device
=GPU-3a23c669-1f69-c64e-cf85-44e9b07e7a2a ubuntu nvidia-smi

The example below exposes the first and third GPUs.

$
 
docker run -it
 --rm
 --gpus
 '"device=0,2"' nvidia-smi

Restart policies (–restart)

Use Docker’s --restart to specify a container’s restart policy. A restart
policy controls whether the Docker daemon restarts a container after exit.
Docker supports the following restart policies:

Policy
Result

no
Do not automatically restart the container when it exits. This is the default.

on-failure[:max-retries]
Restart only if the container exits with a non-zero exit status. Optionally, limit the number of restart retries the Docker daemon attempts.

unless-stopped
Restart the container unless it is explicitly stopped or Docker itself is stopped or restarted.

always
Always restart the container regardless of the exit status. When you specify always, the Docker daemon will try to restart the container indefinitely. The container will also always start on daemon startup, regardless of the current state of the container.

$
 
docker run --restart
=always redis

This will run the redis container with a restart policy of always
so that if the container exits, Docker will restart it.

More detailed information on restart policies can be found in the
Restart Policies (–restart)
section of the Docker run reference page.

Add entries to container hosts file (–add-host)

You can add other hosts into a container’s /etc/hosts file by using one or
more --add-host flags. This example adds a static address for a host named
docker:

$
 
docker run --add-host
=
docker:93.184.216.34 --rm
 -it alpine

/ #
 ping docker
PING docker (93.184.216.34): 56 data bytes
64 bytes from 93.184.216.34: seq=0 ttl=37 time=93.052 ms
64 bytes from 93.184.216.34: seq=1 ttl=37 time=92.467 ms
64 bytes from 93.184.216.34: seq=2 ttl=37 time=92.252 ms
^C
--- docker ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 92.209/92.495/93.052 ms

Sometimes you need to connect to the Docker host from within your
container. To enable this, pass the Docker host’s IP address to
the container using the --add-host flag. To find the host’s address,
use the ip addr show command.

The flags you pass to ip addr show depend on whether you are
using IPv4 or IPv6 networking in your containers. Use the following
flags for IPv4 address retrieval for a network device named eth0:

$
 
HOSTIP
=
`
ip -4
 addr show scope global dev eth0 | grep 
inet | awk
 '{print $2}'
 | cut
 -d
 / -f
 1 | sed
 -n
 1p`
$
 
docker run  --add-host
=
docker:${
HOSTIP
}
 --rm
 -it debian

For IPv6 use the -6 flag instead of the -4 flag. For other network
devices, replace eth0 with the correct device name (for example docker0
for the bridge device).

Set ulimits in container (–ulimit)

Since setting ulimit settings in a container requires extra privileges not
available in the default container, you can set these using the --ulimit flag.
--ulimit is specified with a soft and hard limit as such:
<type>=<soft limit>[:<hard limit>], for example:

$
 
docker run --ulimit
 nofile
=
1024:1024 --rm
 debian sh -c
 "ulimit -n"
1024

Note

If you do not provide a hard limit, the soft limit is used
for both values. If no ulimits are set, they are inherited from
the default ulimits set on the daemon. The as option is disabled now.
In other words, the following script is not supported:
$
 
docker run -it
 --ulimit
 as
=1024 fedora /bin/bash

The values are sent to the appropriate syscall as they are set.
Docker doesn’t perform any byte conversion. Take this into account when setting the values.

For `nproc` usage

Be careful setting nproc with the ulimit flag as nproc is designed by Linux to set the
maximum number of processes available to a user, not to a container. For example, start four
containers with daemon user:

$
 
docker run -d
 -u
 daemon --ulimit
 nproc
=3 busybox top

$
 
docker run -d
 -u
 daemon --ulimit
 nproc
=3 busybox top

$
 
docker run -d
 -u
 daemon --ulimit
 nproc
=3 busybox top

$
 
docker run -d
 -u
 daemon --ulimit
 nproc
=3 busybox top

The 4th container fails and reports “[8] System error: resource temporarily unavailable” error.
This fails because the caller set nproc=3 resulting in the first three containers using up
the three processes quota set for the daemon user.

Stop container with signal (–stop-signal)

The --stop-signal flag sets the system call signal that will be sent to the
container to exit. This signal can be a signal name in the format SIG<NAME>,
for instance SIGKILL, or an unsigned number that matches a position in the
kernel’s syscall table, for instance 9.

The default is defined by STOPSIGNAL
in the image, or SIGTERM if the image has no STOPSIGNAL defined.

Optional security options (–security-opt)

On Windows, this flag can be used to specify the credentialspec option.
The credentialspec must be in the format file://spec.txt or registry://keyname.

Stop container with timeout (–stop-timeout)

The --stop-timeout flag sets the number of seconds to wait for the container
to stop after sending the pre-defined (see --stop-signal) system call signal.
If the container does not exit after the timeout elapses, it is forcibly killed
with a SIGKILL signal.

If --stop-timeout is set to -1, no timeout is applied, and the daemon will
wait indefinitely for the container to exit.

The default is determined by the daemon, and is 10 seconds for Linux containers,
and 30 seconds for Windows containers.

Specify isolation technology for container (–isolation)

This option is useful in situations where you are running Docker containers on
Windows. The --isolation=<value> option sets a container’s isolation technology.
On Linux, the only supported is the default option which uses Linux namespaces.
These two commands are equivalent on Linux:

$
 
docker run -d busybox top
$
 
docker run -d
 --isolation default busybox top

On Windows, --isolation can take one of these values:

Value
Description

default
Use the value specified by the Docker daemon’s --exec-opt or system default (see below).

process
Shared-kernel namespace isolation.

hyperv
Hyper-V hypervisor partition-based isolation.

The default isolation on Windows server operating systems is process, and hyperv
on Windows client operating systems, such as Windows 10. Process isolation has better
performance, but requires that the image and host use the same kernel version.

On Windows server, assuming the default configuration, these commands are equivalent
and result in process isolation:

PS
 
C:\
>
 
docker
 
run
 
-d
 
microsoft/nanoserver
 
powershell
 
echo
 
process

PS
 
C:\
>
 
docker
 
run
 
-d
 
--isolation
 
default
 
microsoft/nanoserver
 
powershell
 
echo
 
process

PS
 
C:\
>
 
docker
 
run
 
-d
 
--isolation
 
process
 
microsoft/nanoserver
 
powershell
 
echo
 
process

If you have set the --exec-opt isolation=hyperv option on the Docker daemon, or
are running against a Windows client-based daemon, these commands are equivalent and
result in hyperv isolation:

PS
 
C:\
>
 
docker
 
run
 
-d
 
microsoft/nanoserver
 
powershell
 
echo
 
hyperv

PS
 
C:\
>
 
docker
 
run
 
-d
 
--isolation
 
default
 
microsoft/nanoserver
 
powershell
 
echo
 
hyperv

PS
 
C:\
>
 
docker
 
run
 
-d
 
--isolation
 
hyperv
 
microsoft/nanoserver
 
powershell
 
echo
 
hyperv

Specify hard limits on memory available to containers (-m, –memory)

These parameters always set an upper limit on the memory available to the container. On Linux, this
is set on the cgroup and applications in a container can query it at /sys/fs/cgroup/memory/memory.limit_in_bytes.

On Windows, this will affect containers differently depending on what type of isolation is used.

With process isolation, Windows will report the full memory of the host system, not the limit to applications running inside the container

  
PS
 
C:\
>
 
docker
 
run
 
-it
 
-m
 
2GB
 
--isolation
=
process
 
microsoft/nanoserver
 
powershell
 
Get-ComputerInfo
 
*
memory
*


  
CsTotalPhysicalMemory
      
:
 
17064509440

  
CsPhyicallyInstalledMemory
 
:
 
16777216

  
OsTotalVisibleMemorySize
   
:
 
16664560

  
OsFreePhysicalMemory
       
:
 
14646720

  
OsTotalVirtualMemorySize
   
:
 
19154928

  
OsFreeVirtualMemory
        
:
 
17197440

  
OsInUseVirtualMemory
       
:
 
1957488

  
OsMaxProcessMemorySize
     
:
 
137438953344

With hyperv isolation, Windows will create a utility VM that is big enough to hold the memory limit, plus the minimal OS needed to host the container. That size is reported as “Total Physical Memory.”

  
PS
 
C:\
>
 
docker
 
run
 
-it
 
-m
 
2GB
 
--isolation
=
hyperv
 
microsoft/nanoserver
 
powershell
 
Get-ComputerInfo
 
*
memory
*


  
CsTotalPhysicalMemory
      
:
 
2683355136

  
CsPhyicallyInstalledMemory
 
:

  
OsTotalVisibleMemorySize
   
:
 
2620464

  
OsFreePhysicalMemory
       
:
 
2306552

  
OsTotalVirtualMemorySize
   
:
 
2620464

  
OsFreeVirtualMemory
        
:
 
2356692

  
OsInUseVirtualMemory
       
:
 
263772

  
OsMaxProcessMemorySize
     
:
 
137438953344

Configure namespaced kernel parameters (sysctls) at runtime (–sysctl)

The --sysctl sets namespaced kernel parameters (sysctls) in the
container. For example, to turn on IP forwarding in the containers
network namespace, run this command:

$
 
docker run --sysctl
 net.ipv4.ip_forward=1 someimage

Note

Not all sysctls are namespaced. Docker does not support changing sysctls
inside of a container that also modify the host system. As the kernel
evolves we expect to see more sysctls become namespaced.

Currently supported sysctls

IPC Namespace:

kernel.msgmax, kernel.msgmnb, kernel.msgmni, kernel.sem,
kernel.shmall, kernel.shmmax, kernel.shmmni, kernel.shm_rmid_forced.
Sysctls beginning with fs.mqueue.*
If you use the --ipc=host option these sysctls are not allowed.