Basics of Docker Technology:
- Docker is a new container technology that is open-source and used for easy way of shipping and running web applications.
- Docker is considered as a best alternative to hypervisors or Virtual Mchines.
- Unlike Virtual Machines, Docker does not need entire host system resources to be used.
- Instead, Docker uses only the kernel and the libraries of the host system.
- Docker technology is of high-speed and offers convenient data storage and data transfer.
- The easy data access facility and light-weight nature of Docker is obtained using layers by Linux kernel.
Major Docker Elements:
The major elements of Docker are Docker container, Docker image and Docker registry.
- Docker image is used for creating Docker containers.
- The base image is used to form other Docker images.
- The Docker images can be obtained from Docker index.
- The Docker container must be run using Docker commands.
- The Docker registry is used to store and manage Docker images.
- The Docker image acts as building components of Docker.
- The Docker registry acts as storage component and the Docker container is the executing component of Docker.
- There are two various kinds of Docker registry namely public and private registry.
- The popular example for Docker registry is ‘Docker Hub’.
- This is used as both public and private registry for storage.
- The public storage allows any user to download and use the images published by other users whereas private registry allows only the user to use images only from own container.
How Docker Technology Works?
- Docker images are first formed from base image.
- Then the Docker container is built from this Docker image.
- The Docker container is used for executing various Docker commands.
- The formed images are then pushed into the Docker registry.
- The Docker images can be browsed from the Docker index.
- Docker image can be downloaded from other containers using ‘PULL’ command.
- PUSH command is used for inserting or sharing your image with other users.
Docker uses Linux technologies:
- Docker technology makes use of various Linux technologies.
- The recent technologies adopted by Docker are namespaces, cgroups and container format.
- Namespaces are used for creating a private workspace.
- Container groups allow secured access and container formats are used for storing various containers.
- The Union file system is adopted by Docker technology for file storage.
- This allows in providing a coherent file system.
- Various file formats can be integrated using this Union file system.
- Though Docker container is read-only, a read-write version is created using a layer on top of the Docker container by Linux kernel.