Knowledge Transfer

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==Docker== is a technology that allows you to build, run, test, and deploy distributed applications. It uses operating-system-level virtualization to deliver software in packages called containers.

Docker Entities

Image

It is a template for environment creation. It has everything your app needs: OS, Software, Code. And might be treated like Snapshot.

Container

Container is a running instance of image

graph LR
  A(IMAGE)-->|RUN| CONTAINER

These containers are isolated from each other and bundle their own tools, libraries, and configuration files. They can communicate with each other through well-defined channels. All containers are run by a single operating system kernel, and therefore use few resources.

Images can be created by either using a
Dockerfile (which contains all the necessary instructions for creating an image) or by using Docker commit, which takes an existing container and creates an image from it.

Ports

Through the port we can communicate with container.

Volumes

Volume creating - it is the way, how we can share files between host and container / between containers.

docker volume create --name volume-data - create our volume

docker run -d -v volume-data:/data --name nginx-test nginx:latest - mount in the container /data folder.

Dockerfile

Dockerfile it is an instruction how to build our container properly.

\#each line creates new layer, each layer have their cache
FROM node:latest
# Open or create dir where you will work
WORKDIR /app
# All further steps will be rerun(cache not used) if there are any changes in this file
ADD package*.json ./
# so all dependencies will be cached and not installed again if package.json not changed
RUN npm install
ADD . .
CMD npm start

FROM adoptopenjdk/openjdk11:jdk-11.0.11_9-alpine-slim
EXPOSE 8092
ARG JAR_FILE=build/libs/PostService-0.0.1-SNAPSHOT.jar
COPY ${JAR_FILE} /app.jar
ENTRYPOINT ["java", "-jar", "app.jar"]

Docker Registries

Highly scalable server side application that stores and lets you distribute Docker images.
Used in your CI/CD Pipeline
Run you applications

Commands


docker attach	Attach local standard input, output, and error streams to a running container
docker build	Build an image from a Dockerfile
docker builder	Manage builds
docker checkpoint	Manage checkpoints
docker commit	Create a new image from a container’s changes
docker config	Manage Docker configs
docker container	Manage containers
docker context	Manage contexts
docker cp	Copy files/folders between a container and the local filesystem
docker create	Create a new container
docker diff	Inspect changes to files or directories on a container’s filesystem
docker events	Get real time events from the server
docker exec	Run a command in a running container(-it for interaction)
docker export	Export a container’s filesystem as a tar archive
docker history	Show the history of an image
docker image	Manage images
docker images	List images
docker import	Import the contents from a tarball to create a filesystem image
docker info	Display system-wide information
docker inspect	Return low-level information on Docker objects
docker kill	Kill one or more running containers
docker load	Load an image from a tar archive or STDIN
docker login	Log in to a Docker registry
docker logout	Log out from a Docker registry
docker logs	Fetch the logs of a container
docker manifest	Manage Docker image manifests and manifest lists
docker network	Manage networks
docker node	Manage Swarm nodes
docker pause	Pause all processes within one or more containers
docker plugin	Manage plugins
docker port	List port mappings or a specific mapping for the container
docker ps	List containers
docker pull	Pull an image or a repository from a registry
docker push	Push an image or a repository to a registry
docker rename	Rename a container
docker restart	Restart one or more containers
docker rm	Remove one or more containers
docker rmi	Remove one or more images
docker run	Create and run a new container from an image
docker save	Save one or more images to a tar archive (streamed to STDOUT by default)
docker search	Search the Docker Hub for images
docker secret	Manage Docker secrets
docker service	Manage services
docker stack	Manage Docker stacks
docker start	Start one or more stopped containers
docker stats	Display a live stream of container(s) resource usage statistics
docker stop	Stop one or more running containers
docker swarm	Manage Swarm
docker system	Manage Docker
docker tag	Create a tag TARGET_IMAGE that refers to SOURCE_IMAGE
docker top	Display the running processes of a container
docker trust	Manage trust on Docker images
docker unpause	Unpause all processes within one or more containers
docker update	Update configuration of one or more containers
docker volume	Manage volumes
docker wait	Block until one or more containers stop, then print their exit codes

Docker Compose

version: '3.8'
services:
  redis:
    image: redis:6.2-alpine
    restart: always
    ports:
      - '6379:6379'
      - '8001:8001'
    command: redis-server --save 20 1 --loglevel warning --requirepass eYVX7EwVmmxKPCDmwMtyKVge8oLd2t81
    volumes: 
      - redis:/data
volumes:
  redis:
    driver: './redis'