Docker advance1
- 2. TOPICS • Docker Installation • Docker Network • Docker Volume • Dockerfile
- 3. DOCKER INSTALLATION • Docker comes in 2 editions Docker CE (Community edition) and Docker EE (Enterprise Edition). Stable – gives you latest releases for general availability. Test – gives pre-releases that are ready for testing before general availability. Nightly – gives you the latest builds of work in progress for the next major release.
- 4. INSTALL DOCKER ENGINE ON CENTOS • SET UP THE REPOSITORY $ sudo yum install -y yum-utils $ sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo $ sudo yum-config-manager --enable docker-ce-nightly $ sudo yum-config-manager --enable docker-ce-test $ sudo yum-config-manager --disable docker-ce-nightly Install the latest version of Docker Engine $ sudo yum install docker-ce docker-ce-cli containerd.io $ sudo systemctl start docker $ sudo docker run hello-world
- 5. CONT.. • Uninstall old versions $ sudo yum remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine
- 6. DOCKER NETWORKING • One of the reasons Docker containers and services are so powerful is that you can connect them together, or connect them to non-Docker workloads. • Network drivers 1. Bridge 2. Host 3. Overlay 4. Macvlan
- 7. BRIDGE • The default network driver. • If you don’t specify a driver, this is the type of network you are creating. • Bridge networks are usually used when your applications run in standalone containers that need to communicate.
- 9. TYPES OF BRIDGE • User-defined bridges • Default bridge
- 10. USER-DEFINED BRIDGES • User-defined bridges provide automatic DNS resolution between containers: Containers on the default bridge network can only access each other by IP addresses, unless you use the --link option, which is considered legacy. On a user-defined bridge network, containers can resolve each other by name or alias. • User-defined bridges provide better isolation: All containers without a --network specified, are attached to the default bridge network. This can be a risk, as unrelated stacks/services/containers are then able to communicate.
- 11. CONT… • Containers can be attached and detached from user-defined networks on the fly: During a container’s lifetime, you can connect or disconnect it from user-defined networks on the fly. To remove a container from the default bridge network, you need to stop the container and recreate it with different network options. • Each user-defined network creates a configurable bridge: If your containers use the default bridge network, you can configure it, but all the containers use the same settings, such as MTU and iptables rules. In addition, configuring the default bridge network happens outside of Docker itself, and requires a restart of Docker.
- 12. COMMAND • $ docker network create my-net new network bridge creation • $ ifconfig To verify the bridge configuration • docker create --name my-nginx --network my-net --publish 8080:80 nginx:latest docker network connect my-net my-nginx docker network disconnect my-net my-nginx docker network rm my-net Remove the newly created bridge
- 13. DOCKER VOLUMES • Volumes are the preferred mechanism for persisting data generated by and used by Docker containers. • Volumes are easier to back up or migrate than bind mounts. • You can manage volumes using Docker CLI commands or the Docker API. • Volumes work on both Linux and Windows containers. • Volumes can be more safely shared among multiple containers. • Volume drivers let you store volumes on remote hosts or cloud providers, to encrypt the contents of volumes, or to add other functionality. • New volumes can have their content pre-populated by a container. • Command Flags –v or --mount
- 14. CREATE AND MANAGE VOLUMES • Create a volume: docker volume create my-vol • List volumes: docker volume ls • Inspect a volume: docker volume inspect my-vol • Remove a volume: docker volume rm my-vol
- 15. START A CONTAINER WITH A VOLUME • With flag --mount docker run -d --name devtest --mount source=myvol2,target=/app nginx:latest • With Flag –v docker run -d --name devtest -v myvol2:/app nginx:latest
- 16. CONT… • Run the CMD, docker inspect devtest Check the parameters • Removing CMD, docker container stop devtest docker container rm devtest docker volume rm myvol2
- 17. START A SERVICE WITH VOLUMES docker service create -d --replicas=4 --name devtest-service --mount source=myvol2,target=/app nginx:latest $ docker service ps devtest-service docker inspect nginxtest docker service rm devtest-service
- 18. READ-ONLY VOLUME docker run -d --name=nginxtest -v nginx-vol:/usr/share/nginx/html:ro nginx:latest docker run -d --name=nginxtest --mount source=nginx- vol,destination=/usr/share/nginx/html,readonly nginx:latest docker inspect nginxtest
- 19. DOCKERFILE • A Dockerfile is a script/text configuration file that contains collections of commands and instructions that will be automatically executed in sequence in the docker environment for building a new docker image.This file is written in a popular, human-readable Markup Language called YAML. • The docker build command processes this file generating a Docker Image in your Local Image Cache, which you can then start-up using the docker run command, or push to a permanent Image Repository.
- 20. COMPONENTS OF DOCKERFILE • FROM FROM php:5.6-apache The first part is the FROM command, which tells us what image to base this off of. This is the multi-layered approach that makes Docker so efficient and powerful. In this instance, it’s using the php:5.6-apache Docker image, which again references a Dockerfile to automate the build process. • MAINTAINER The MAINTAINER instruction sets the Author field of the generated images. • RUN RUN a2enmod rewrite The next set of calls are the RUN commands. This is what runs within the container at build time. From the calls, you can see that ModRewrite is enabled (RUN a2enmod rewrite), and it then installs the php-gd and libraries required to run it.
- 21. CONT… • VOLUME VOLUME /var/www/html This is the default volume we overrode in the last article. Specifying it in the Dockerfile allows it to be externally mounted via the host itself or a Docker data container. • ENV ENV WORDPRESS_VERSION 4.2.2 This sets the environment variables, which can be used in the Dockerfile and any scripts that it calls. These are persistent with the container too, so they can be referenced at any time. • COPY COPY docker-entrypoint.sh /entrypoint.sh The COPY command is simply as it sounds. It can copy a file (in the same directory as the Dockerfile) to the container. You can do this for things like custom configuration files or like in this instance, a file to run commands after the container has been set up.
- 22. CONT… • ENTRYPOINT The ENTRYPOINT specifies a command that will always be executed when the container starts. • CMD The CMD specifies arguments that will be fed to the ENTRYPOINT.
- 23. DOCKERFILE BUILD • Example From ubuntu Maintainer "Debashis" RUN apt-get update RUN apt-get install vim -y CMD /bin/echo "Hello! Welcome to docker Tutorial!!!“ • Build sudo docker build -t demo:image01 . sudo docker image ls sudo docker run c2a181f68d62
- 24. DOCKER IMAGE PUSH • Create the Repo in hub.docker.com • docker login • docker build -t nathdeb006/demo-image:image02 . • docker image ls • docker push nathdeb006/demo-image:image02 • Go to Docker hub and check