Docker

what is the docker?

Docker is an open source engine that makes it easy to create a lightweight, portable, self-contained container for any application. Developers compile the test on the notebook through the container can be deployed in the production environment, including VMs (virtual machine), bare metal, OpenStack cluster and other basic application platform.

Why use docker

Faster delivery and deployment

Developers can use a standard mirror to build a development container, the development is completed, the operation and maintenance personnel can directly use the container to deploy the code. Docker can quickly create containers, quickly iterate the application, and make the whole process visible, so that other members of the team easier to understand how the application is created and working. Docker container is very light soon! Container start-up time is seconds, a lot of time to save development, testing, deployment time.

More efficient virtualization

The Docker container does not require additional hypervisor support, it is kernel-level virtualization, so you can achieve higher performance and efficiency.

Easier migration and extension

Docker containers can run on almost any platform, including physical machines, virtual machines, public clouds, private clouds, personal computers, servers and so on. This compatibility allows users to migrate an application directly from one platform to another.

Isolation

Docker ensures that your application is separated from the resources.

safety

Docker ensures that applications running in the container and other applications in the container are completely separate and isolated, giving you complete control over traffic traffic and management. The Docker container can not spy on processes that run in other containers. From an architectural point of view, each container uses only its own resources (from process to network stack).

docker basic use

Image

Is a read-only template that runs the Docker container.

Container

Responsible for the operation of the application, including the operating system, the user to add the file and metadata
A container is a run instance created from a mirror. It can be started, started, stopped, deleted. Each container is isolated from each other to ensure a safe platform.

Note: The mirror is read-only, and the container creates a writeable layer as the uppermost layer at startup.

Repository

The warehouse is a place where the image files are stored centrally.

Warehouse is divided into public warehouse (Public) and private warehouse (Private) two forms.

The relationship between the image and the container is like a class and an instance of an object-oriented program. The mirror is a static definition, and the container is a mirror runtime entity. The container can be created, started, stopped, deleted, paused, and so on

Mirror
Basic command
Login, log out to a Docker mirror repository, if not specified mirror storage address, the default for the official warehouse Docker Hub
docker login [OPTIONS] [SERVER]
docker logout [OPTIONS] [SERVER]
Extract or update the specified mirror from the mirror repository
docker pull [OPTIONS] NAME [: TAG | @DIGEST]
Upload the local image to the mirror repository and log in to the mirror repository
docker push [OPTIONS] NAME [: TAG]
Search docker image
docker search [OPTIONS] TERM
View the mirror details
docker inspect [image-id]
List the local image
docker images [OPTIONS] [REPOSITORY [: TAG]]
Delete one or more mirrors locally
docker rmi [OPTIONS] IMAGE [IMAGE ...]
Mark the local image, put it in a warehouse
docker tag [OPTIONS] IMAGE [: TAG] [REGISTRYHOST /] [USERNAME /] NAME [: TAG]
Create a mirror using Dockerfile
docker build [OPTIONS] PATH | URL |
Save the specified image as a tar archive
docker save [OPTIONS] IMAGE [IMAGE ...]

container
Containers can be divided into two types:
Interactive container: the front run, you can interact with the container through the console. If the terminal that created the container is closed, the container becomes a stop state. In addition, entering exit in the container console or docker stop or docker kill can also terminate the container.
Background container: the background to run, after the creation of the boot has nothing to do with the terminal, and need to use docker stop or docker kill to terminate.
Basic command
Create a new container and run a command
docker run [OPTIONS] IMAGE [COMMAND] [ARG ...]
Create a new container but do not start it
docker create [OPTIONS] IMAGE [COMMAND] [ARG ...]
Start, stop, restart, kill one or more containers that have been stopped
docker start [OPTIONS] CONTAINER [CONTAINER ...]
docker stop [OPTIONS] CONTAINER [CONTAINER ...]
docker restart [OPTIONS] CONTAINER [CONTAINER ...]
docker kill [OPTIONS] CONTAINER [CONTAINER ...]
Delete one or more containers
docker rm [OPTIONS] CONTAINER [CONTAINER ...]
List containers
docker ps [OPTIONS]
Lists the port mapping for the specified container
docker port [OPTIONS] CONTAINER [PRIVATE_PORT [/ PROTO]]
Create a new image from the container
docker commit [OPTIONS] CONTAINER [REPOSITORY [: TAG]]
Used for a copy of the data between the container and the host
docker cp [OPTIONS] CONTAINER: SRC_PATH DEST_PATH | -
docker cp [OPTIONS] SRC_PATH | - CONTAINER: DEST_PATH

Upload image
Local mirror production using the commit command and the preparation of Dockerfile two ways.
docker login (docker hub account)
docker commit [container-id] [dockerhub_name / name]
docker push [dockerhub_name / name]

Dockerfile is a more transparent and repeatable way of making, because we do not manually perform the operation, but all the operations with Docker commands and syntax provided to the Dockerfile. Command name all uppercase, commonly used Dockerfile command are:
FROM: Specifies which parent mirror to extend from.
RUN: Execute the command to modify the mirror. Such as RUN apt-get update and RUN ["apt-get", "update"]. The former executes the command in / bin / sh, which is executed directly using the system call exec.
EXPOSE: Specifies the port that is open to the container. You can also use the -p parameter to open some ports that are not listed in the Dockerfile when the container starts.
ADD: Add the host host file, folder, or URL to specify the resource to the mirror.
ENV: Sets the environment variable for the container to run.
USER: Specifies the user for the operation of the container and the commands following the Dockerfile.
WORKDIR: specify the working directory (the last one will be working as a container after the start of the directory)
VOLUME: Mount the file
CMD and ENTRYPOINT: Specifies the command to be executed after the container is started
ONBUILD: Specifies that some commands are not executed when the current mirror is built, but is fired when the submirror is constructed.

Build image
docker build -t [dockerhub_name / name] [dockerfile path] (.)