docker container create

Description

Create a new container

Usage

docker container create [OPTIONS] IMAGE [COMMAND] [ARG...]

Options

Parent command

Related commands

Extended description

Creates a writeable container layer over the specified image and prepares it for running the specified command. The container ID is then printed to STDOUT. This is similar to docker run -d except the container is never started. You can then use the **docker start ** command to start the container at any point.

The initial status of the container created with docker create is ‘created’.

OPTIONS

The CONTAINER-DIR must be an absolute path such as /src/docs. The HOST-DIR can be an absolute path or a name value. A name value must start with an alphanumeric character, followed by a-z0-9, _ (underscore), . (period) or - (hyphen). An absolute path starts with a / (forward slash).

If you supply a HOST-DIR that is an absolute path, Docker bind-mounts to the path you specify. If you supply a name, Docker creates a named volume by that name. For example, you can specify either /foo or foo for a HOST-DIR value. If you supply the /foo value, Docker creates a bind-mount. If you supply the foo specification, Docker creates a named volume.

You can specify multiple -v options to mount one or more mounts to a container. To use these same mounts in other containers, specify the –volumes-from option also.

You can add :ro or :rw suffix to a volume to mount it read-only or read-write mode, respectively. By default, the volumes are mounted read-write. See examples.

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 a 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.

By default bind mounted volumes are private. That means any mounts done inside container will not be visible on host and vice-a-versa. One can change this behavior by specifying a volume mount propagation property. Making a volume shared mounts done under that volume inside container will be visible on host and vice-a-versa. Making a volume slave enables only one way mount propagation and that is mounts done on host under that volume will be visible inside container but not the other way around.

To control mount propagation property of volume one can use :[r]shared, :[r]slave or :[r]private propagation flag. Propagation property can be specified only for bind mounted volumes and not for internal volumes or named volumes. For mount propagation to work source mount point (mount point where source dir is mounted on) has to have right propagation properties. For shared volumes, source mount point has to be shared. And for slave volumes, source mount has to be either shared or slave.

Use df <source-dir> to figure out the source mount and then use findmnt -o TARGET,PROPAGATION <source-mount-dir> to figure out propagation properties of source mount. If findmnt utility is not available, then one can look at mount entry for source mount point in /proc/self/mountinfo. Look at optional fields and see if any propagaion properties are specified. shared:X means mount is shared, master:X means mount is slave and if nothing is there that means mount is private.

To change propagation properties of a mount point use mount command. For example, if one wants to bind mount source directory /foo one can do mount --bind /foo /foo and mount --make-private --make-shared /foo. This will convert /foo into a shared mount point. Alternatively one can directly change propagation properties of source mount. Say / is source mount for /foo, then use mount --make-shared / to convert / into a shared mount.

Note: When using systemd to manage the Docker daemon’s start and stop, in the systemd unit file there is an option to control mount propagation for the Docker daemon itself, called MountFlags. The value of this setting may cause Docker to not see mount propagation changes made on the mount point. For example, if this value is slave, you may not be able to use the shared or rshared propagation on a volume.

To disable automatic copying of data from the container path to the volume, use the nocopy flag. The nocopy flag can be set on bind mounts and named volumes.

EXAMPLES

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. On Microsoft Windows, you can specify these values:

• default: Use the value specified by the Docker daemon’s --exec-opt . If the daemon does not specify an isolation technology, Microsoft Windows uses process as its default value.
• process: Namespace isolation only.
• hyperv: Hyper-V hypervisor partition-based isolation.

Specifying the --isolation flag without a value is the same as setting --isolation="default".

Examples

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. On Microsoft Windows, you can specify these values:

• default: Use the value specified by the Docker daemon’s --exec-opt . If the daemon does not specify an isolation technology, Microsoft Windows uses process as its default value.
• process: Namespace isolation only.
• hyperv: Hyper-V hypervisor partition-based isolation.

Specifying the --isolation flag without a value is the same as setting --isolation="default".

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