On August 10, a video course on Docker started in Slurm , in which we analyze it in full - from basic abstractions to network parameters.
In this article, we'll talk about the history of Docker and its main abstractions: Image, Cli, Dockerfile. The lecture is designed for beginners, so it is unlikely to be of interest to experienced users. There will be no blood, no appendix and no deep diving. The very basics.
What is Docker
Let's take a look at the definition of Docker from Wikipedia.
Docker is software for automating the deployment and management of applications in containerized environments.
Nothing is clear from this definition. It is especially unclear what "containerization-enabled environments" mean. To understand, let's go back to the past. Let's start with the era that I conventionally call the "Monolithic era".
Monolithic era
— 2000-, , . . , . :
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: VMware, VirtualBox, Hyper-V, Qemu KVM . . , . , . — . — , , Nginx, Apache, MySQL. , . , . , .
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Networking Namespace / . Mount — . User — .
Control Groups: Memory, CPU, IOPS, Network — 12 . Cgroups («C-»).
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, : Capabilities, Copy-on-write .
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Docker
Docker :
- Docker Daemon — Container Engine; .
- Docker CLI — Docker.
- Dockerfile — , .
- Image — , .
- Container.
- Docker registry — .
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docker ps — , Docker-.
docker images — , .
docker search <> — registry.
docker pull <> — registry .
docker build <</path/to/dir>> — .
docker run <> — .
docker rm <> — .
docker logs <> —
docker start/stop/restart <> —
, , 70% Docker .
Dockerfile — . — . .
Dockerfile: , — . , ( Dockerfile), Image.
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Image Dockerfile. Dockerfile . .
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Container — , . Dockerfile , . , . — . , , Docker.
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: « Docker».
: , Kubernetes, Southbridge, .