Installing Docker in CentOS

sudo yum install -y yum-utils
sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo
sudo yum install docker-ce --allowerasing
sudo systemctl enable docker && systemctl start docker

For other OS, you may refer the official documentation here https://docs.docker.com/engine/install/

Verify if docker command works

sudo systemctl status docker 

Finding details about your docker installation

docker info

Listing docker images in the local docker registry

docker images

Downloading images from Docker Hub Remote Registry

docker pull hello-world:latest
docker pull ubuntu:16.04

Deleting unwanted images from local docker registry

docker rmi hello-world:latest

Creating containers

docker run hello-world:latest

Listing the containers

docker ps -a

Listing only running containers

docker ps

Creating a ubuntu container interactively

docker run -it --name ubuntu1 --hostname ubuntu1 ubuntu:16.04 /bin/bash

Installing ifconfig utility inside container

root@ubuntu1:/# apt update && apt install -y net-tools
root@ubuntu1:/# ifconfig

The expected output is

root@ubuntu1:/# ifconfig
eth0      Link encap:Ethernet  HWaddr 02:42:ac:11:00:02  
          inet addr:172.17.0.2  Bcast:172.17.255.255  Mask:255.255.0.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2877 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2336 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:19712773 (19.7 MB)  TX bytes:130632 (130.6 KB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

root@ubuntu1:/# 

Listing the running containers from another terminal(tab)

docker ps

Exiting the container from within interactive container shell

root@ubuntu1:/# exit

At this point ubuntu1 container has exited

docker ps

Starting the stopped container

docker start ubuntu1`

Opening a second shell inside the already running container

docker exec -it ubuntu1 /bin/bash
root@ubuntu1:/# exit

Exiting the second shell we launched using the above exec command will not exit the container.

Stopping a container

docker stop ubuntu1
docker stop ubuntu2 ubuntu3

Remove running containers graciously

docker stop ubuntu1 
docker rm ubuntu1

Removing containers forcibly

docker rm -f ubuntu2

Stopping and Removing multiple containers

docker stop $(docker ps -q)
docker rm $(docker ps -aq)

Removing multiple containers abruptly

docker rm -f $(docker ps -aq)

Restarting a container

docker restart ubuntu1

Installing JDK 11

sudo yum install -y java-11-openjdk-devel

Verify if JDK is installed properly

java -version
javac -version

Installing Maven

cd ~/Downloads
wget https://mirrors.estointernet.in/apache/maven/maven-3/3.8.2/binaries/apache-maven-3.8.2-bin.tar.gz
tar xvfz apache-maven-3.8.2-bin.tar.gz

Adding Maven into environment settings

cd ~/Downloads
cd apache-maven-3.8.2
pwd

Cloning TekTutor Jenkins repository (Do it as rps user)

cd ~
git clone https://github.com/tektutor/jenkins-aug-2021.git

Building Hello java application and run the automated test cases

cd jenkins-aug-2021/Day1/Hello
mvn clean test

Set up JFrog artifactory using Docker

docker run -d --name artifactory --hostname artifactory -p 8081:8081 jfrog-docker-reg2.bintray.io/jfrog/artifactory-oss:4.1.0

See if the artifactory container runs properly

docker psThis time c1 will be able to ping c2

If you are able to see the artifactory container running, you may access the artifactory web page at http://localhost:8081

Login Credentials

User - admin
Password - password

Creating custom network in docker

docker network create my-network-1
docker network create my-network-2

Listing docker networks

docker network ls

Creating a container c1 and adding the container to our custom network

docker run -dit --name c1 --hostname c1 --network my-network-1 ubuntu:16.04 bash

Creating a container c2 and adding the container to our custom network

docker run -dit --name c2 --hostname c2 --network my-network-2 ubuntu:16.04 bash

Ascii diagram of c1 and c2 connected to two different custom networks

+-----------------------------------------+               +-----------------------------------------+
|                                         |               |                                         |
|                                         |               |                                         |
|                                         |               |                                         |
|                                         |               |                                         |
|                                         |               |                                         |
|           +-----------------+           |               |          +-----------------+            |
|           |                 |           |               |          |                 |            |
|           |                 |           |               |          |   Container     |            |
|           |     Container   |           |               |          |      C2         |            |
|           |        C1       |           |               |          |   172.19.0.2    |            |
|           |     172.18.0.2  |           |               |          |                 |            |
|           +-----------------+           |               |          +-----------------+            |
|                                         |               |                                         |
|             172.18.0.0/16               |               |             172.19.0.0/16               |
|             my-network-1                |               |             my-network-2                |
|                                         |               |                                         |
|                                         |               |                                         |
|                                         |               |                                         |
+-----------------------------------------+               +-----------------------------------------+

Get inside c1 shell

docker exec -it c1 bash
apt update && apt install -y net-tools iputils-ping

Find the ip address of c1 from within c1 shell

hostname -i

Get inside c2 shell in another terminal

docker exec -it c2 bash
apt update && apt install -y net-tools iputils-ping

Find the IP address of c2 from within c2

hostname -i

Ping c1 from c2

ping 172.18.0.2

As you can notice, c1 won't be able to ping c2 as they are in two different networks.

Ping c2 from c1

ping 172.19.0.2

As you can notice, c2 won't be able to ping c1 as they are in two different networks.

Now let's connect c1 to my-network-2

docker network connect my-network-2 c1
docker inspect c1 | grep IPA

Now c1 container will have two IPs as it is connected to two different networks.

Get inside c1 and verify if c1 can ping c2

docker exec -it c1 bash
ping 172.19.0.2

This time c1 will be able to ping c2

Get inside c2 and verify if c2 can ping c1

docker exec -it c2 bash
ping 172.19.0.3

This time c2 will be able to ping c1