Docker getting started

Dockers 

Why dockers?
    Docker provides environment to run applications in a container, which allow to isolate any OS dependencies or library dependencies.

Some useful links:
https://docs.docker.com/get-started/
https://linuxize.com/post/how-to-install-and-use-docker-on-centos-7/




Installation instructions For Centos:


## Un-install older docker versions.



sudo yum remove docker \

>                   docker-client \

>                   docker-client-latest \

>                   docker-common \

>                   docker-latest \

>                   docker-latest-logrotate \

>                   docker-logrotate \

>                   docker-engine

##Install these tool/libs before installing docker.
yum install -y yum-utils \ device-mapper-persistent-data \ lvm2
## Setup repository
yum-config-manager \ --add-repo \ https://download.docker.com/linux/centos/docker-ce.repo
## install docker CE ##
For latest docker
yum install docker-ce docker-ce-cli containerd.io


For particular version
yum install docker-ce-18.06.3.ce-3.el7 docker-ce-cli-18.06.3.ce-3.el7

start docker daemon boot:

sudo systemctl start docker
sudo systemctl enable docker

Check status

sudo systemctl status docker

Test your installation

docker run hello-world 

Example pulling official CentOS environment:

1. Create a directory for exmapl

"mkdir docker_test"

2. go to docker_test and create "Dockerfile"

This will have instructions on what to do like , ADD, RUN , COPY etc.

---

RUN rm -rf /etc/yum.repos.d/*.repo

COPY pkey-c /home/2.03-16/data/pkey-c 

RUN useradd -ms /bin/bash hsm

ADD https://github.com/krallin/tini/releases/download/v0.18.0/tini-static /tini

RUN chmod +x /tini

ADD bin /bin

ADD lib /lib

ADD opt /opt

ADD etc /etc

---

3. Now build "docker build ."

4. Now run the installation

docker image ls

[root@localhost composetest]# docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE friendlyhello latest 97ce9a216075 10 minutes ago 84.5MB python 3.4-alpine c06adcf62f6e 7 weeks ago 72.9MB hello-world latest fce289e99eb9 4 months ago 1.84kB

5. Now start running the image

docker run -it 9f38484d220f /bin/bash

6. To connect multiple cli sessions
docker exec -it ba02d5d832aa /bin/bash

7. To see which docker processes running
docker ps
8. Docker logs

docker logs | more

  EX:

docker logs 9e3284f1a9d0 | more

9. Docker stop : "docker stop "
10. Docker image remove
   ## This wil remove images whihc are dangling ##
  docker rmi $(sudo docker images --filter "dangling=true" -q --no-trunc)

  ## find the dependent images and remove . below goofy_easley was using centos##
  docker rm goofy_easley docker rmi 9f38484d220f

11. Copying files to running docker. 

 docker cp ../LiquidSecurity-NFBE-2.03-15.03.tgz   ba02d5d832aa:/root/

12. How do you rebuild docker?
13. How to start a process on docker start?

14.  Are docker images filling up your disk space. Following command will clean it up.

      "docker system prune -a --volumes"

15. Running Docker in non root mode. 

1.       $sudo groupadd dokcer
2.       $sudo usermod -AG docker
3.   Now logout and login
1.  run "docker run hello-wrold"