Shulou(Shulou.com)06/02 Report--

Container for sharing cloud computing training for good programmers: container is actually a kind of sandboxie technology. Sandboxie is the technology that can "load" your application like a container. In this way, applications and applications will not interfere with each other because of the boundary, and applications loaded into containers can also be moved around conveniently.

Question: what is the nature of a container?

The essence of a container is a process. The container image is the ".exe" installation package in this system.

.iso Image File-> (linux/wind/) docker- download images-run- > docker Container-Packaging-images--- to another Machine-run Image-Container

Docker-download the image imagesc7---jdk,tomcat-- package it into images---- and export it to another machine-- run-images--- container

Docker introduction:

Docker is an open source container engine project based on lightweight virtualization technology from Docker.Inc. The whole project is developed in Go language and conforms to the Apache 2.0 protocol. Through hierarchical image standardization and kernel virtualization technology, Docker enables application developers and operation engineers to publish applications across platforms in a unified way, and to provide a resource-isolated application running environment with almost no additional overhead.

Docker is an open source tool that makes it easy to create and manage Linux containers. * * containers are like lightweight virtual machines and can be started or stopped in seconds. **

Official website: docker.com

Docker.io-docker official library is also called docker-hub

When there is no container:

1.rd development products (need to configure the development environment) lamp

two。 Testing (need to configure the test environment)

3.op online (online environment is required)

Development, testing, operation and maintenance

After there is a container:

00001. Rd development products (need to configure the development environment in the docker container)

00002. Package the container into an image and give it to OPS. OPS's online Docker is different from the original tools: the traditional deployment mode is: install (package management tool or source package compilation)-> configure-> run; the deployment mode of Docker is: copy-> run. Changes brought about by Docker to server-side development / deployment: convenient and rapid deployment can greatly reduce the time and labor costs of deployment. Docker supports packaging applications into a portable container, redefining the process of application development, testing, and deployment. The core idea is Build once, Run anywhere 1) standardize application release, and docker containers include running environment and executable programs. Can be used across platforms and hosts 2) save time, rapid deployment and startup, VM startup is generally minutes, docker container startup is seconds; 3) it is convenient to build systems based on micro-service architecture, through service choreography, better loose coupling; 4) cost savings. Previously, a virtual machine needs at least a few gigabytes of disk space, and the docker container can be reduced to MB level.

Docker advantages:

1. Standardization of deliverables

Docker's standardized delivery is called "mirroring", which includes the application and the operating environment on which it depends, greatly simplifying the mode of application delivery.

2. Application isolation

Docker can isolate the interaction between different applications, but it is less expensive than virtual machines. In short, container technology deployment speed, development, testing more agile, improve system utilization, reduce resource costs.

3. Build once and deliver multiple times

Similar to the container "once packed, multiple shipped", Docker images can be "built once, delivered multiple times".

Metrics for Docker:

Docker is a lightweight virtual technology implemented by containers, which ensures isolation while saving resources. Docker's

Portability allows it to be built at once and run everywhere. Docker can be measured from the following four aspects:

1) isolation

Through the namespace of the kernel, the container's processes, networks, messages, file systems, and hostnames are isolated.

2) measurability

Docker mainly controls the measurement and allocation of resources through the cgroups control group.

3) portability

Docker uses AUFS to achieve rapid updates to containers.

AUFS is a file system that supports mounting different directories to the same virtual file system and supports the management of read and write permissions for each directory. AUFS has layers

The concept of each modification is to make incremental changes in the existing write-only layer, and the modified content will form a new file layer without affecting the original layer.

4) Security

Security can be divided into security between containers, and security between containers and managed hosts.

Security between containers is mainly ensured through namespaces and cgroups.

The security between the container and the managed host is mainly controlled by the kernel capability mechanism, which can prevent Docker from illegally invading the managed host.

The Docker container uses AUFS as the file system, which has the following advantages:

1) Save storage space

Multiple containers can share the same underlying image storage.

2) Rapid deployment

3) easy to upgrade

Upgrading a base image can affect all containers based on it. It should be noted that docker containers that are already running are not affected.

The main differences between containers and VM:

Surface differences:

The container occupies a small volume, while the virtual machine occupies a large volume.

Isolation: containers provide process-based isolation, while virtual machines provide complete isolation of resources.

Startup speed: the virtual machine may take a minute to start, while the container may only take a second or less.

The container uses the kernel of the host operating system, while the virtual machine uses a separate kernel. One of the limitations of Docker is that it can only be used on 64-bit operating systems.

Essential difference:

The container is an isolated process

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