mirror of https://github.com/docker/docs.git
370 lines
20 KiB
YAML
370 lines
20 KiB
YAML
amd64: |
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AMD64 is AMD's 64-bit extension of Intel's x86 architecture, and is also
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referred to as x86_64 (or x86-64).
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aufs: |
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aufs (advanced multi layered unification filesystem) is a Linux [filesystem](#filesystem) that
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Docker supports as a storage backend. It implements the
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[union mount](http://en.wikipedia.org/wiki/Union_mount) for Linux file systems.
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base image: |
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An image that has no parent is a **base image**.
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boot2docker: |
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[boot2docker](http://boot2docker.io/) is a lightweight Linux distribution made
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specifically to run Docker containers. The boot2docker management tool for Mac
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and Windows was deprecated and replaced by [`docker-machine`](#machine) which
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you can install with the Docker Toolbox.
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btrfs: |
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btrfs (B-tree file system) is a Linux [filesystem](#filesystem) that Docker
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supports as a storage backend. It is a [copy-on-write](http://en.wikipedia.org/wiki/Copy-on-write)
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filesystem.
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build: |
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build is the process of building Docker images using a [Dockerfile](#dockerfile).
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The build uses a Dockerfile and a "context". The context is the set of files in the
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directory in which the image is built.
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cgroups: |
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cgroups is a Linux kernel feature that limits, accounts for, and isolates
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the resource usage (CPU, memory, disk I/O, network, etc.) of a collection
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of processes. Docker relies on cgroups to control and isolate resource limits.
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*Also known as : control groups*
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cluster: |
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A cluster is a group of machines that work together to run workloads and provide high availability.
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collection: |
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A collection is a group of swarm resources that Docker Engine - Enterprise uses for role-based
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access control. Collections enable organizing permissions for resources like
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nodes, services, containers, volumes, networks, and secrets. [Learn how to manage collections](/datacenter/ucp/2.2/guides/access-control/manage-access-with-collections/).
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Compose: |
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[Compose](https://github.com/docker/compose) is a tool for defining and
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running complex applications with Docker. With Compose, you define a
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multi-container application in a single file, then spin your
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application up in a single command which does everything that needs to
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be done to get it running.
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*Also known as : docker-compose, fig*
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copy-on-write: |
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Docker uses a
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[copy-on-write](/engine/userguide/storagedriver/imagesandcontainers/#/the-copy-on-write-strategy)
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technique and a [union file system](#union file system) for both images and
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containers to optimize resources and speed performance. Multiple copies of an
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entity share the same instance and each one makes only specific changes to its
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unique layer.
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Multiple containers can share access to the same image, and make
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container-specific changes on a writable layer which is deleted when
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the container is removed. This speeds up container start times and performance.
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Images are essentially layers of filesystems typically predicated on a base
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image under a writable layer, and built up with layers of differences from the
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base image. This minimizes the footprint of the image and enables shared
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development.
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For more about copy-on-write in the context of Docker, see [Understand images,
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containers, and storage
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drivers](/engine/userguide/storagedriver/imagesandcontainers/).
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container: |
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A container is a runtime instance of a [docker image](#image).
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A Docker container consists of
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- A Docker image
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- An execution environment
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- A standard set of instructions
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The concept is borrowed from Shipping Containers, which define a standard to ship
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goods globally. Docker defines a standard to ship software.
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Docker: |
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The term Docker can refer to
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- The Docker project as a whole, which is a platform for developers and sysadmins to
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develop, ship, and run applications
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- The docker daemon process running on the host which manages images and containers
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(also called Docker Engine)
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Docker Enterprise: |
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Docker Enterprise is a platform to build, ship, and run
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containerized applications, that you can deploy in the cloud or on-premise. It
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includes a tested and certified version of Docker, web UIs for managing
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your app resources, and support.
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Docker Desktop for Mac: |
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[Docker Desktop for Mac](/docker-for-mac/) is an easy-to-install, lightweight
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Docker development environment designed specifically for the Mac. A native
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Mac application, Docker Desktop for Mac uses the macOS Hypervisor
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framework, networking, and filesystem. It's the best solution if you want
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to build, debug, test, package, and ship Dockerized applications on a
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Mac. Docker Desktop for Mac supersedes [Docker Toolbox](#toolbox) as
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state-of-the-art Docker on macOS.
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Docker Desktop for Windows: |
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[Docker Desktop for Windows](/docker-for-windows/) is an
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easy-to-install, lightweight Docker development environment designed
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specifically for Windows 10 systems that support Microsoft Hyper-V
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(Professional, Enterprise and Education). Docker Desktop for Windows uses Hyper-V for
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virtualization, and runs as a native Windows app. It works with Windows Server
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2016, and gives you the ability to set up and run Windows containers as well as
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the standard Linux containers, with an option to switch between the two. Docker
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for Windows is the best solution if you want to build, debug, test, package, and
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ship Dockerized applications from Windows machines. Docker Desktop for Windows
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supersedes [Docker Toolbox](#toolbox) as state-of-the-art Docker on Windows.
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Docker Hub: |
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The [Docker Hub](https://hub.docker.com/) is a centralized resource for working with
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Docker and its components. It provides the following services:
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- Docker image hosting
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- User authentication
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- Automated image builds and work-flow tools such as build triggers and web hooks
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- Integration with GitHub and Bitbucket
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Dockerfile: |
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A Dockerfile is a text document that contains all the commands you would
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normally execute manually in order to build a Docker image. Docker can
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build images automatically by reading the instructions from a Dockerfile.
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ENTRYPOINT: |
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In a Dockerfile, an `ENTRYPOINT` is an optional definition for the first part
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of the command to be run. If you want your Dockerfile to be runnable without
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specifying additional arguments to the `docker run` command, you must specify
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either `ENTRYPOINT`, `CMD`, or both.
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- If `ENTRYPOINT` is specified, it is set to a single command. Most official
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Docker images have an `ENTRYPOINT` of `/bin/sh` or `/bin/bash`. Even if you
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do not specify `ENTRYPOINT`, you may inherit it from the base image that you
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specify using the `FROM` keyword in your Dockerfile. To override the
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`ENTRYPOINT` at runtime, you can use `--entrypoint`. The following example
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overrides the entrypoint to be `/bin/ls` and sets the `CMD` to `-l /tmp`.
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```bash
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$ docker run --entrypoint=/bin/ls ubuntu -l /tmp
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```
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- `CMD` is appended to the `ENTRYPOINT`. The `CMD` can be any arbitrary string
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that is valid in terms of the `ENTRYPOINT`, which allows you to pass
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multiple commands or flags at once. To override the `CMD` at runtime, just
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add it after the container name or ID. In the following example, the `CMD`
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is overridden to be `/bin/ls -l /tmp`.
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```bash
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$ docker run ubuntu /bin/ls -l /tmp
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```
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In practice, `ENTRYPOINT` is not often overridden. However, specifying the
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`ENTRYPOINT` can make your images more flexible and easier to reuse.
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filesystem: |
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A file system is the method an operating system uses to name files
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and assign them locations for efficient storage and retrieval.
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Examples :
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- Linux : ext4, aufs, btrfs, zfs
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- Windows : NTFS
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- macOS : HFS+
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grant: |
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A grant enables role-based access control for managing how users and
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organizations access Docker Engine - Enterprise swarm resources. A grant is made up of a
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subject, a role, and a collection. For more about grants and role-based access
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control, see [Grant permissions to users based on roles](/datacenter/ucp/2.2/guides/access-control/grant-permissions/).
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image: |
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Docker images are the basis of [containers](#container). An Image is an
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ordered collection of root filesystem changes and the corresponding
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execution parameters for use within a container runtime. An image typically
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contains a union of layered filesystems stacked on top of each other. An image
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does not have state and it never changes.
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Kitematic: |
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A legacy GUI, bundled with [Docker Toolbox](#toolbox), for managing Docker
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containers. We recommend upgrading to [Docker Desktop for Mac](#docker for Mac) or
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[Docker Desktop for Windows](#docker for Windows), which have superseded Kitematic.
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layer: |
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In an image, a layer is modification to the image, represented by an instruction in the
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Dockerfile. Layers are applied in sequence to the base image to create the final image.
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When an image is updated or rebuilt, only layers that change need to be updated, and
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unchanged layers are cached locally. This is part of why Docker images are so fast
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and lightweight. The sizes of each layer add up to equal the size of the final image.
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libcontainer: |
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libcontainer provides a native Go implementation for creating containers with
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namespaces, cgroups, capabilities, and filesystem access controls. It allows
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you to manage the lifecycle of the container performing additional operations
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after the container is created.
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libnetwork: |
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libnetwork provides a native Go implementation for creating and managing container
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network namespaces and other network resources. It manages the networking lifecycle
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of the container performing additional operations after the container is created.
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link: |
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links provide a legacy interface to connect Docker containers running on the
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same host to each other without exposing the hosts' network ports. Use the
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Docker networks feature instead.
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Machine: |
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[Machine](https://github.com/docker/machine) is a Docker tool which
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makes it really easy to create Docker hosts on your computer, on
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cloud providers and inside your own data center. It creates servers,
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installs Docker on them, then configures the Docker client to talk to them.
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*Also known as : docker-machine*
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namespace: |
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A [Linux namespace](http://man7.org/linux/man-pages/man7/namespaces.7.html)
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is a Linux kernel feature that isolates and virtualizes system resources. Processes which restricted to
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a namespace can only interact with resources or processes that are part of the same namespace. Namespaces
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are an important part of Docker's isolation model. Namespaces exist for each type of
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resource, including `net` (networking), `mnt` (storage), `pid` (processes), `uts` (hostname control),
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and `user` (UID mapping). For more information about namespaces, see [Docker run reference](/engine/reference/run/)
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and [Introduction to user namespaces](https://success.docker.com/KBase/Introduction_to_User_Namespaces_in_Docker_Engine).
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node: |
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A [node](/engine/swarm/how-swarm-mode-works/nodes/) is a physical or virtual
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machine running an instance of the Docker Engine in swarm mode.
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**Manager nodes** perform swarm management and orchestration duties. By default
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manager nodes are also worker nodes.
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**Worker nodes** execute tasks.
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overlay network driver: |
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Overlay network driver provides out of the box multi-host network connectivity
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for docker containers in a cluster.
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overlay storage driver: |
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OverlayFS is a [filesystem](#filesystem) service for Linux which implements a
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[union mount](http://en.wikipedia.org/wiki/Union_mount) for other file systems.
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It is supported by the Docker daemon as a storage driver.
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parent image: |
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An image's **parent image** is the image designated in the `FROM` directive
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in the image's Dockerfile. All subsequent commands are applied to this parent
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image. A Dockerfile with no `FROM` directive has no parent image, and is called
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a **base image**.
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persistent storage: |
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Persistent storage or volume storage provides a way for a user to add a persistent layer to the running container's file system. This persistent layer could live on the container host or an external device. The lifecycle of this persistent layer is not connected to the life cycle of the container, allowing a user to retain state.
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registry: |
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A Registry is a hosted service containing [repositories](#repository) of [images](#image)
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which responds to the Registry API.
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The default registry can be accessed using a browser at [Docker Hub](#docker hub)
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or using the `docker search` command.
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repository: |
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A repository is a set of Docker images. A repository can be shared by pushing it
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to a [registry](#registry) server. The different images in the repository can be
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labeled using [tags](#tag).
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Here is an example of the shared [nginx repository](https://hub.docker.com/_/nginx/)
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and its [tags](https://hub.docker.com/r/library/nginx/tags/).
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role: |
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A role is a set of permitted API operations on a collection of Docker Engine - Enterprise swarm
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resources. As part of a grant, a role is assigned to a subject (a user, team, or
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organization) and a collection. For more about roles, see [Roles and
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permission levels](/datacenter/ucp/2.2/guides/access-control/permission-levels/).
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role-based access control: |
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Role-based access control enables managing how Docker Engine - Enterprise users can access
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swarm resources. UCP administrators create grants to control how users access
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resource collections. A grant is made up of a subject, a role, and a collection.
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A grant defines who (subject) has how much access (role) to a set of resources
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(collection). For more about role-based access control, see
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[Authentication](/datacenter/ucp/2.2/guides/access-control/).
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SSH: |
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SSH (secure shell) is a secure protocol for accessing remote machines and applications.
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It provides authentication and encrypts data communication over insecure networks such
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as the Internet. SSH uses public/private key pairs to authenticate logins.
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service: |
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A [service](/engine/swarm/how-swarm-mode-works/services/) is the definition of how
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you want to run your application containers in a swarm. At the most basic level
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a service defines which container image to run in the swarm and which commands
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to run in the container. For orchestration purposes, the service defines the
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"desired state", meaning how many containers to run as tasks and constraints for
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deploying the containers.
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Frequently a service is a microservice within the context of some larger
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application. Examples of services might include an HTTP server, a database, or
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any other type of executable program that you wish to run in a distributed
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environment.
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service discovery: |
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Swarm mode [service discovery](/engine/swarm/networking/#use-swarm-mode-service-discovery) is a DNS component
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internal to the swarm that automatically assigns each service on an overlay
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network in the swarm a VIP and DNS entry. Containers on the network share DNS
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mappings for the service via gossip so any container on the network can access
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the service via its service name.
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You don’t need to expose service-specific ports to make the service available to
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other services on the same overlay network. The swarm’s internal load balancer
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automatically distributes requests to the service VIP among the active tasks.
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subject: |
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A subject represents a user, team, or organization in Docker Enterprise. A subject is
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granted a role for access to a collection of swarm resources.
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For more about role-based access, see [Authentication](/datacenter/ucp/2.2/guides/access-control/).
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swarm: |
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A [swarm](/engine/swarm/) is a cluster of one or more Docker Engines running in [swarm mode](#swarm mode).
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Docker Swarm: |
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Do not confuse [Docker Swarm](https://github.com/docker/swarm) with the [swarm mode](#swarm mode) features in Docker Engine.
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Docker Swarm is the name of a standalone native clustering tool for Docker.
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Docker Swarm pools together several Docker hosts and exposes them as a single
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virtual Docker host. It serves the standard Docker API, so any tool that already
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works with Docker can now transparently scale up to multiple hosts.
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*Also known as : docker-swarm*
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swarm mode: |
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[Swarm mode](/engine/swarm/) refers to cluster management and orchestration
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features embedded in Docker Engine. When you initialize a new swarm (cluster) or
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join nodes to a swarm, the Docker Engine runs in swarm mode.
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tag: |
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A tag is a label applied to a Docker image in a [repository](#repository).
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Tags are how various images in a repository are distinguished from each other.
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*Note : This label is not related to the key=value labels set for docker daemon.*
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task: |
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A [task](/engine/swarm/how-swarm-mode-works/services/#/tasks-and-scheduling) is the
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atomic unit of scheduling within a swarm. A task carries a Docker container and
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the commands to run inside the container. Manager nodes assign tasks to worker
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nodes according to the number of replicas set in the service scale.
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The diagram below illustrates the relationship of services to tasks and
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containers.
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Toolbox: |
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[Docker Toolbox](/toolbox/overview/) is a legacy
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installer for Mac and Windows users. It uses Oracle VirtualBox for
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virtualization.
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For Macs running OS X El Capitan 10.11 and newer macOS releases, [Docker Desktop for
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Mac](/docker-for-mac/) is the better solution.
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For Windows 10 systems that support Microsoft Hyper-V (Professional, Enterprise
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and Education), [Docker Desktop for
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Windows](/docker-for-windows/) is the better solution.
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Union file system: |
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Union file systems implement a [union
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mount](https://en.wikipedia.org/wiki/Union_mount) and operate by creating
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layers. Docker uses union file systems in conjunction with
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[copy-on-write](#copy-on-write) techniques to provide the building blocks for
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containers, making them very lightweight and fast.
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For more on Docker and union file systems, see [Docker and AUFS in
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practice](/engine/userguide/storagedriver/aufs-driver/),
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[Docker and Btrfs in
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practice](/engine/userguide/storagedriver/btrfs-driver/),
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and [Docker and OverlayFS in
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practice](/engine/userguide/storagedriver/overlayfs-driver/).
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Example implementations of union file systems are
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[UnionFS](https://en.wikipedia.org/wiki/UnionFS),
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[AUFS](https://en.wikipedia.org/wiki/Aufs), and
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[Btrfs](https://btrfs.wiki.kernel.org/index.php/Main_Page).
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virtual machine: |
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A virtual machine is a program that emulates a complete computer and imitates dedicated hardware.
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It shares physical hardware resources with other users but isolates the operating system. The
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end user has the same experience on a Virtual Machine as they would have on dedicated hardware.
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Compared to containers, a virtual machine is heavier to run, provides more isolation,
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gets its own set of resources and does minimal sharing.
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*Also known as : VM*
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volume: |
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A volume is a specially-designated directory within one or more containers
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that bypasses the Union File System. Volumes are designed to persist data,
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independent of the container's life cycle. Docker therefore never automatically
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delete volumes when you remove a container, nor will it "garbage collect"
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volumes that are no longer referenced by a container.
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*Also known as: data volume*
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There are three types of volumes: *host, anonymous, and named*:
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- A **host volume** lives on the Docker host's filesystem and can be accessed from within the container.
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- A **named volume** is a volume which Docker manages where on disk the volume is created,
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but it is given a name.
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- An **anonymous volume** is similar to a named volume, however, it can be difficult, to refer to
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the same volume over time when it is an anonymous volumes. Docker handle where the files are stored.
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x86_64: |
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x86_64 (or x86-64) refers to a 64-bit instruction set invented by AMD as an
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extension of Intel's x86 architecture. AMD calls its x86_64 architecture,
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AMD64, and Intel calls its implementation, Intel 64.
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