Linux & DevOPS.: Orchestration

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<a href="https://1.bp.blogspot.com/-299-axy3ef0/Xddd0rknA-I/AAAAAAAADfA/DwGscRMI7Ew5CaVmbY6SLoKA6QI5lfjoACPcBGAYYCw/s1600/Docker.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="225" data-original-width="225" height="200" src="https://1.bp.blogspot.com/-299-axy3ef0/Xddd0rknA-I/AAAAAAAADfA/DwGscRMI7Ew5CaVmbY6SLoKA6QI5lfjoACPcBGAYYCw/s200/Docker.jpg" width="200" /></a>Basic Docker tutorial | Docker Cheet Sheet | Docker Guide | Learn Docker </h3>
 
 
 
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Docker Introduction</h4>
Docker tool was introduced in order to make it easier for you to create, deploy, and run applications by using containers. Containers provision you the packaging of your application with all the important components it requires, like libraries and other dependencies, and ship them all out as one package. Due to which you as a developer can be assured that your application will run on any other machine. 
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Docker Architecture</h4>
We will start from understanding Docker’s Architecture and main aspects in it, then we will continue with the important commands required for docker installation, build, push, run, ship etc. operations. 
DevOps architecture consists of these 5 main entities which are Registry, Images, Containers, Docker Daemon and Client. 
 
 
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<li>Registry: It hosts the public and official images, docker registry that we use is Dockerhub.</li>
<li>Images: It can be downloaded from the registry directly or implicitly when starting a container.</li>
<li>Containers: They are basically instances of the images, multiple containers for a single image is possible.</li>
<li>Docker daemon: Daemon creates, runs and monitors the containers along with building and storing the images.</li>
<li>Client: Client talks to daemon via http.</li>
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Docker Orchestrate</h4>
Orchestration is used for managing the container’s lifecycle especially in dynamic environments. 
It is used for controlling and automating many tasks for the container. There are many Docker Orchestration tools like Docker Swarm, Kubernetes etc, and we’re using Docker Swarm commands below, let’s check the commands used for Docker Orchestration. 
 
Commands: 
 
    To initialize swarm mode and listen to a specific interface. 
 
       #  Docker swarm init --advertise-addr 10.1.0.2 
 
    Join an existing swarm as manager node 
 
        Docker swarm join --token<manager-token> 10.1.0.2:2377 
 
    Join a swarm as a worker node 
 
        Docker swarm join --token<worker-token> 10.1.0.2:2377 
 
    List all the nodes in the swarm 
 
        Docker node ls 
 
    Create a service from an image on the existing port and deploy 3 instances 
 
        Docker service create --replicas 3 -p 80:80 name -webngix 
 
    List services running in swarm 
 
       #  docker service ls 
 
    Scale a service 
 
        # docker service scale web=5 
 
    List tasks of a service 
 
        # docker service ps web 
 
 
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Docker Build</h4>

Build command is used for building images from a docker file. Let’s check some of essential docker build commands. 
Commands: 
 
    To build the image from the docker file and tag image 
 
        Docker build -t myapp :1.0 
 
    List all images that are locally stored 
 
        Docker images 
 
    Delete an image from the docker store 
 
        Docker rmi alpine: 3.4 
 
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Docker Run</h4>
Run command is used for creating a container from a specified image. Check these run commands for your reference. 
Commands: 
 
    To create and run a command: 
        Docker run –name container_name docker_image 
    Flags used: 
        -d detach container on start 
        -rm remove container once it stops 
        -p publish host ip and host port to the container por 
        -v define and share volume across containers 
        –read-only sets it to read only permission 
       
Docker Ship 
 
Docker gives you the capability of shipping your application container anywhere, on any platform, let’s check some commands for it. 
Commands: 
 
    To pull an image from the registry 
        Docker pull alpine:3.4. 
    Retag a local image with a new image name 
        Docker tag alpine:3.4 myrepo/ myalpine:3.4 
    Log in to a registry 
        Docker login my.registry.com:8000 
    Push an image to a registry 
        Docker push myrepo/ myalpine:3.4 
 
 
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Docker Clean up</h4>
To prevent from wasting the resources, you must know how to clean, we are providing few essential commands for same. 
Commands: 
 
    To clean unused/dangling images: 
        Docker image prune 
    To remove images not used in containers 
        Docker image prune -a 
    To prune the entire system 
        Docker system prune 
    To leave a swarm 
        Docker swarm leave 
    To remove a swarm 
        Docker stack rm stack_name 
    To kill all running containers 
        Docker kill $ (docker ps -q) 
    To delete all stopped containers 
        docker rm $(docker ps -a -q) 
    To delete all images 
        docker rmi $(docker images -q) 
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Docker  Services</h4>
Let’s take a sneak peek over the commands used for viewing the running services, run the services, to view all service logs and to scale the services. 
Commands: 
 
    List of all services running in a swarm 
        Docker service ls 
    To see all running services 
        Docker stack services stack_name 
    To see all service logs 
        Docker service logs stack_name service_names 
    To scale service across qualified nodes 
        Docker service scale stack_name_service_name= replicas 
        
        
Interaction with a container 
 
Let’s check how to make an interaction with a container 
 
    Run a command in the container 
        Docker exe -ti container_name command.sh 
    Follow the container logs 
        Docker logs -ft container name 
    Save a running container as an image 
        Docker commit -m “commit message” -a “author” container_name username/image_name: tag 
 
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Docker Important terms</h4>
Some of the important terms while using docker container. 
 
 
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<li>    Docker Layer: Read-only files to provision the system</li>
<li>    Docker Image: Read only layer that is the base of the image</li>
<li>    Docker Container: A runnable instance of the image</li>
<li>    Docker Registry/hub: Central place where images live</li>
<li>    Docker machine: A VM to run docker containers</li>
<li>    Docker compose: A VM to run multiple containers as a system.</li>
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Docker Basic Tutorial

Basic Docker tutorial | Docker Cheet Sheet | Docker Guide | Learn Docker Docker Introduction Docker tool was introduced in order to ...