advantage

container advantage

1. easy to develop
2. easy to deploy

What is container？

1. Layers of images：only different layers are downloaded
2. Mostly Linux Base Image, small in size
3. Application image on top

Difference between Docker Image and Docker Container?

Docker Image

1. the actual package
2. artifact，that can be moved around
3. not running

Docker Container

1. actually start the application
2. container environment is created
3. running

Docker vs Virtual Machine

Application — OS Kernel — Hardware

Docker

1. Application layer, it uses host OS Kernel
2. docker image’s size smaller than VM
3. running speed faster

Virtual Machine

1. Both Application And its own OS kernel.
2. good Compatibility than Docker

Installing Docker

1. doc url (opens new window)
2. pre-requirement
3. docker-toolbox that brige enable OS to run docker

Common Command

1. docker pull [name]:[version] if no version, then will get the latest version.
2. docket images : show list images you have pulled
3. docker run [xxx]: to run an image ; -d daemon; -p bind host port to container port. —name：specify a name.

docker run -d -p6000:6379 —name redis redis

1. docker ps : show you have running containers; -a: show history you have running.
2. docker stop [containerId]：gracelly stop the running container.

Debug docker

1. docker log [containerId]/[container name]：show logs when docker running an images.
2. docker exec -it(inside terminal) [containerId/containerName] /bin/bash：check running container’s running state

docker log redis
docker exec -it redis /biin/bash

docker run vs docker start

docker run: create a new container
docker start: restart a stopped container

Docker compose

1. specify the docker run command in yaml file.
2. every config can map to the docker run command

Docker file

1. start by basing it on another image
2. optionally define environment variables（recommend）
3. run — execute any linux command
4. copy — execute command on the HOST machine
5. CMD[”node” , “server.js”] — execute node server.js command

• CMD = entrypoint command
• docker file is blueprint of any docker image, that means any docker image is on the docker hub should be built on its own docker file.
• when you adjust the Dockerfile, you MUST rebuild the Image

docker build -t name:tag

docker registry

author use A.W.S for example.

docker tag name:tage  xxx/cloudserver/name:tag  -- 重命名
docker push xxx/cloudserver/name:tag            -- 推送docker to docker repository     

Deploy containered image

The Server needs to login to pull from PRIVETE repository；Login not needed for PUBLIC DockerHub.

Docker Volumes

When do we need Docker Volumes?

Data is gone! When restarting or removing the container. The container has virtual file system which is mapping the host’s physical file system.

3 Volume Types

1. Host Volume：you decide where on the host file system the reference is made.

docker run -v host file dir : container file dir

2. Anonymous Volumes：for each container a folder is generated that gets mounted.

docker run -v /var/lib/mysql/data --> /var/lib/docker/volumes/random-hash/_data

3. Named Volumes：you can reference the volume by name; （👍👍👍）

docker run -v name:/var/lib/mysql/data

how to use it to persite docker data?

1. config it on docker-compose.yaml

version:'3'
services: 
	mongodb:
  images: mongo
	ports:
		- 27017:27017
	volumes:
		- mongo-data:/data/db [mysql:var/lib/mysql / postgres: var/lib/postgresql/data]
  xxx-other config
volumes:
	mongo-data:
	driver: local

2. Docker Volume Locations
   1. Windows：C:\ProgramData\docker\volumes
   2. Linux：/var/lib/docker/volumes
   3. Mac：/var/lib/docker/volumes