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Tuesday, August 2, 2016

Docker basic operations demo

Installing and Configuring Docker



Video




Main Tasks


1.Install Docker

2.Install CONTAINER

3.Starting CONTAINER


4. Copying files to & from CONTAINER

5. Installing webserver in CONTAINER and 

     acccessing it

6. Saving Docker image

7. Building Docker image

8.Exporting and importing docker images






1.1 Add docker repo
    vi /etc/yum.repos.d/docker.repo


File should be like :


A. For centos , similar to RHL distribution


[dockerrepo]


name=Docker Repository

baseurl=https://yum.dockerproject.org/repo/main/centos/7/

enabled=1

gpgcheck=1

gpgkey=https://yum.dockerproject.org/gpg




B. For Ubuntu : deb distribution



    sudo apt-get install apt-transport-https ca-certificates
  1. sudo apt-get install apt-transport-https ca-certificates
  2. sudo vi /etc/apt/sources.list.d/docker.list


docker.list should contains

deb https://apt.dockerproject.org/repo ubuntu-xenial main



    sudo apt-get update
    sudo apt-get purge lxc-docker
    sudo apt-cache policy docker-engine
  1. sudo apt-get install linux-image-extra-$(uname -r)
  2. sudo apt-get install docker.io





1.2 Install via yum
    yum install docker-engine


1.3 Add init.d for server to come up automatically after reboot

    chkconfig docker on

          in Ubuntu

    sudo systemctl enable docker

          



1.4 Start the docker process

    service docker start






2. Install docker CONTAINER

2.1 : Pull the latest centos
    docker pull centos

SnapShot :


Using default tag: latest

latest: Pulling from library/centos

3d8673bd162a: Pull complete

Digest: 

sha256:a66ffcb73930584413de83311ca11a4cb4938c9b2521d331026dad970c19adf4

Status: Downloaded newer image for centos:latest


3.Starting CONTAINER


3.1 start the container process
    docker run -it centos




[root@localhost ~]# docker run -it centos

[root@8b173a99e5f7 /]#

[root@8b173a99e5f7 /]# uname -a

Linux 8b173a99e5f7 3.10.0-327.el7.x86_64 #1 SMP Thu 

Nov 19 22:10:57 UTC 2015 x86_64 x86_64 x86_64 

GNU/Linux

[root@8b173a99e5f7 /]#


4. Copying files to & from CONTAINER










From Host OS to CONTAINER (push )


    docker cp <Container>:/root/Fromdocker.tiff .




From CONTAINER to Host

    docker cp <Container>:/root/Fromdocker.tiff /home/oracle








5. Installing webserver in CONTAINER and acccessing it .


In container

5.1
    yum install httpd


Create simple cgi script
    vi /var/www/cgi-bin/date.cgi


#!/bin/bash
echo "Content-type: text/html"
echo ""
echo "<html><head><title>SERVER STATUS "
echo "</title></head><body>"
echo "<h1> SERVER PINGS </h1>"
echo "</body></html>"




Start the http process in CONTAINER



    /usr/sbin/httpd


This will show the ip address
AH00558: httpd: Could not reliably 

determine the server's fully qualified 
domain name, using 172.17.0.2. Set the 

'ServerName' directive globally to 

suppress this message




Other method is in host server run



    docker inspect 8b173a99e5f7 | grep IPAddress


Access http server from Host
    wget http://172.17.0.2/cgi-bin/date.cgi




To access outside of HOST OS , you need to SSH tunnening



    ssh -N -L <OUTSIDEPORT>:<CONTAINERIP:PORT> username@<HOSTOS>


Example : ssh -N -L 8080:172.17.0.2:80 root@172.16.102.142




Another option is save the image and start with port forwarding .


6. Saving Docker image


6.1
    docker images


docker images


REPOSITORY TAG IMAGE ID CREATED SIZE

centos latest 970633036444 16 hours ago 196.7 MB


6.2

docker comit <CONTAINER> repo:TAG
    docker commit 8b173a99e5f7 centos:httpd









docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
centos httpd 77e976c360ed 4 seconds ago 664.1 MB
centos latest 970633036444 16 hours ago 196.7 MB








6.3

stoping CONTAINER
    docker stop 8b173a99e5f7


docker ps


shows all running CONTAINER


6.4 starting docker with httpd process



    docker run -d -p 80:80 centos:httpd /usr/sbin/httpd -D FOREGROUND


after this web server can be access via host server 

port .


7. Building Docker image




7.1 Creating docker file

    vi Dockerfile


FROM centos:httpd
MAINTAINER A D Ministator email: user@master.company.com


EXPOSE 80


ENTRYPOINT /usr/sbin/httpd -D FOREGROUND




Expose 80 , it will open port 80 from container


Entry point command to in docker, in foreground


7.2 Bulding image

Option A

    docker build -t centos:httpd  .


Sending build context to Docker daemon 2.048 kB

Step 1 : FROM centos:httpd

---> ea0a5995178a

Step 2 : MAINTAINER A D Ministator email: 

user@master.company.com

---> Running in 1237e8916daa

---> 60c37cb46920

Removing intermediate container 1237e8916daa

Step 3 : EXPOSE 80

---> Running in fc4ca921a05b

---> d39d12367bfa

Removing intermediate container fc4ca921a05b

Step 4 : ENTRYPOINT /usr/sbin/httpd -D 

FOREGROUND

---> Running in f04320581760

---> cee47177f39f

Removing intermediate container f04320581760

Successfully built cee47177f39f




7.3.1 Starting options

    docker run -it centos:httpd


this will start process in foreground , and promt will be open and no access to server .


[root@localhost httpd]# docker run -it centos:httpd

AH00558: httpd: Could not reliably determine the 

server's fully qualified domain name, using 

172.17.0.2. Set the 'ServerName' directive globally to 

suppress this message




Clt+C is required to stop the process .




7.3.2 with using -d -P option , this will run in back 

ground with opening new port is host to access it



    docker run -it -d -P centos:httpd


[root@localhost httpd]# docker run -it -d -P 

centos:httpd

44ef230f4eb2d127194ad6983d740516312c87781fd2bb61c60148556c49c84d






[root@localhost httpd]# docker ps

CONTAINER ID IMAGE COMMAND CREATED 

STATUS PORTS NAMES

44ef230f4eb2 centos:httpd "/bin/sh -c '/usr/sbi" About 

a minute ago Up About a minute 0.0.0.0:32771->80/tcp determined_hugle




Outside of Host can be access this via port 32771 .

To stop this get the docker CONTAINER ID and stop 

it


Option B : To start the httpd server and get 

interactive mode to work 

Change the Docker file


7.4

    vi Dockerfile


FROM centos:httpd

MAINTAINER A D Ministator email: 

user@master.company.com


RUN echo "/usr/sbin/httpd" >> /root/.bashrc


EXPOSE 80




ENTRYPOINT /bin/bash




7.5

    docker build -t centos:httpd


Sending build context to Docker daemon 2.048 kB


Step 1 : FROM centos:httpd


---> e16e66235220

Step 2 : MAINTAINER A D Ministator email: 

user@master.company.com

---> Running in b4b55bb424b6

---> 7a2872939817

Removing intermediate container b4b55bb424b6

Step 3 : RUN echo "/usr/sbin/httpd" >> /root/.bashrc

---> Running in 8ea971955893

---> 954b2ffbefa3

Removing intermediate container 8ea971955893

Step 4 : EXPOSE 80

---> Running in 798f8f742615

---> 39484e2d99b3

Removing intermediate container 798f8f742615

Step 5 : ENTRYPOINT /bin/bash

---> Running in 25568d2988f0

---> 519165f43eda

Removing intermediate container 25568d2988f0

Successfully built 519165f43eda




7.6 to start




    docker run -it centos:httpd


[root@localhost httpd]# docker run -it centos:httpd


AH00558: httpd: Could not reliably determine the 

server's fully qualified domain name, using 

172.17.0.2. Set the 'ServerName' directive globally to 

suppress this message


[root@f86f2c71b543 /]#

[root@f86f2c71b543 /]# exit

exit




8.Exporting and importing docker images


8.1 exporting

    docker save centos:httpd > http.tar

 ls -l -h http.tar

-rw-r--r--. 1 root root 643M Jul 30 06:52 http.tar


Copy this to other docker server


Import


8.2 importing

    docker load < http.tar








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