44 KiB
| title | description | keywords |
|---|---|---|
| run | The run command description and usage | run, command, container |
run
Usage: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
Run a command in a new container
Options:
--add-host value Add a custom host-to-IP mapping (host:ip) (default [])
-a, --attach value Attach to STDIN, STDOUT or STDERR (default [])
--blkio-weight value Block IO (relative weight), between 10 and 1000
--blkio-weight-device value Block IO weight (relative device weight) (default [])
--cap-add value Add Linux capabilities (default [])
--cap-drop value Drop Linux capabilities (default [])
--cgroupns string Cgroup namespace to use
'host': Run the container in the Docker host's cgroup namespace
'private': Run the container in its own private cgroup namespace
'': Use the default Docker daemon cgroup namespace specified by the `--default-cgroupns-mode` option
--cgroup-parent string Optional parent cgroup for the container
--cidfile string Write the container ID to the file
--cpu-count int The number of CPUs available for execution by the container.
Windows daemon only. On Windows Server containers, this is
approximated as a percentage of total CPU usage.
--cpu-percent int Limit percentage of CPU available for execution
by the container. Windows daemon only.
The processor resource controls are mutually
exclusive, the order of precedence is CPUCount
first, then CPUShares, and CPUPercent last.
--cpu-period int Limit CPU CFS (Completely Fair Scheduler) period
--cpu-quota int Limit CPU CFS (Completely Fair Scheduler) quota
-c, --cpu-shares int CPU shares (relative weight)
--cpus NanoCPUs Number of CPUs (default 0.000)
--cpu-rt-period int Limit the CPU real-time period in microseconds
--cpu-rt-runtime int Limit the CPU real-time runtime in microseconds
--cpuset-cpus string CPUs in which to allow execution (0-3, 0,1)
--cpuset-mems string MEMs in which to allow execution (0-3, 0,1)
-d, --detach Run container in background and print container ID
--detach-keys string Override the key sequence for detaching a container
--device value Add a host device to the container (default [])
--device-cgroup-rule value Add a rule to the cgroup allowed devices list
--device-read-bps value Limit read rate (bytes per second) from a device (default [])
--device-read-iops value Limit read rate (IO per second) from a device (default [])
--device-write-bps value Limit write rate (bytes per second) to a device (default [])
--device-write-iops value Limit write rate (IO per second) to a device (default [])
--disable-content-trust Skip image verification (default true)
--dns value Set custom DNS servers (default [])
--dns-option value Set DNS options (default [])
--dns-search value Set custom DNS search domains (default [])
--domainname string Container NIS domain name
--entrypoint string Overwrite the default ENTRYPOINT of the image
-e, --env value Set environment variables (default [])
--env-file value Read in a file of environment variables (default [])
--expose value Expose a port or a range of ports (default [])
--group-add value Add additional groups to join (default [])
--health-cmd string Command to run to check health
--health-interval duration Time between running the check (ns|us|ms|s|m|h) (default 0s)
--health-retries int Consecutive failures needed to report unhealthy
--health-timeout duration Maximum time to allow one check to run (ns|us|ms|s|m|h) (default 0s)
--health-start-period duration Start period for the container to initialize before counting retries towards unstable (ns|us|ms|s|m|h) (default 0s)
--help Print usage
-h, --hostname string Container host name
--init Run an init inside the container that forwards signals and reaps processes
-i, --interactive Keep STDIN open even if not attached
--io-maxbandwidth string Maximum IO bandwidth limit for the system drive (Windows only)
(Windows only). The format is `<number><unit>`.
Unit is optional and can be `b` (bytes per second),
`k` (kilobytes per second), `m` (megabytes per second),
or `g` (gigabytes per second). If you omit the unit,
the system uses bytes per second.
--io-maxbandwidth and --io-maxiops are mutually exclusive options.
--io-maxiops uint Maximum IOps limit for the system drive (Windows only)
--ip string IPv4 address (e.g., 172.30.100.104)
--ip6 string IPv6 address (e.g., 2001:db8::33)
--ipc string IPC namespace to use
--isolation string Container isolation technology
--kernel-memory string Kernel memory limit
-l, --label value Set meta data on a container (default [])
--label-file value Read in a line delimited file of labels (default [])
--link value Add link to another container (default [])
--link-local-ip value Container IPv4/IPv6 link-local addresses (default [])
--log-driver string Logging driver for the container
--log-opt value Log driver options (default [])
--mac-address string Container MAC address (e.g., 92:d0:c6:0a:29:33)
-m, --memory string Memory limit
--memory-reservation string Memory soft limit
--memory-swap string Swap limit equal to memory plus swap: '-1' to enable unlimited swap
--memory-swappiness int Tune container memory swappiness (0 to 100) (default -1)
--mount value Attach a filesystem mount to the container (default [])
--name string Assign a name to the container
--network-alias value Add network-scoped alias for the container (default [])
--network string Connect a container to a network
'bridge': create a network stack on the default Docker bridge
'none': no networking
'container:<name|id>': reuse another container's network stack
'host': use the Docker host network stack
'<network-name>|<network-id>': connect to a user-defined network
--no-healthcheck Disable any container-specified HEALTHCHECK
--oom-kill-disable Disable OOM Killer
--oom-score-adj int Tune host's OOM preferences (-1000 to 1000)
--pid string PID namespace to use
--pids-limit int Tune container pids limit (set -1 for unlimited)
--privileged Give extended privileges to this container
-p, --publish value Publish a container's port(s) to the host (default [])
-P, --publish-all Publish all exposed ports to random ports
--pull string Pull image before running ("always"|"missing"|"never") (default "missing")
--read-only Mount the container's root filesystem as read only
--restart string Restart policy to apply when a container exits (default "no")
Possible values are : no, on-failure[:max-retry], always, unless-stopped
--rm Automatically remove the container when it exits
--runtime string Runtime to use for this container
--security-opt value Security Options (default [])
--shm-size bytes Size of /dev/shm
The format is `<number><unit>`. `number` must be greater than `0`.
Unit is optional and can be `b` (bytes), `k` (kilobytes), `m` (megabytes),
or `g` (gigabytes). If you omit the unit, the system uses bytes.
--sig-proxy Proxy received signals to the process (default true)
--stop-signal string Signal to stop a container (default "SIGTERM")
--stop-timeout int Timeout (in seconds) to stop a container
--storage-opt value Storage driver options for the container (default [])
--sysctl value Sysctl options (default map[])
--tmpfs value Mount a tmpfs directory (default [])
-t, --tty Allocate a pseudo-TTY
--ulimit value Ulimit options (default [])
-u, --user string Username or UID (format: <name|uid>[:<group|gid>])
--userns string User namespace to use
'host': Use the Docker host user namespace
'': Use the Docker daemon user namespace specified by `--userns-remap` option.
--uts string UTS namespace to use
-v, --volume value Bind mount a volume (default []). The format
is `[host-src:]container-dest[:<options>]`.
The comma-delimited `options` are [rw|ro],
[z|Z], [[r]shared|[r]slave|[r]private],
[delegated|cached|consistent], and
[nocopy]. The 'host-src' is an absolute path
or a name value.
--volume-driver string Optional volume driver for the container
--volumes-from value Mount volumes from the specified container(s) (default [])
-w, --workdir string Working directory inside the container
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".
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.
See also the docker cp command.
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
--deviceoption 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
--deviceoption is only supported on process-isolated Windows containers. This option fails if the container isolation ishypervor when running Linux Containers on Windows (LCOW).
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 createcommand.
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, thesoft limitis used for both values. If noulimitsare set, they are inherited from the defaultulimitsset on the daemon. Theasoption 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 SIGTERM if not specified.
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
processisolation, Windows will report the full memory of the host system, not the limit to applications running inside the containerPS 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
hypervisolation, 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=hostoption these sysctls are not allowed.
Network Namespace:
- Sysctls beginning with
net.* - If you use the
--network=hostoption using these sysctls are not allowed.