In the realm of DevOps, orchestrating seamless workflows is imperative, and Jenkins, with its extensibility, stands out as a powerhouse. 

In this comprehensive tutorial, we will delve into the integration of Docker and SSH for Jenkins agents, providing a step-by-step guide to enhance your CI/CD pipelines. You can see the previous guide, namely setup Jenkins on Kubernetes

Prerequisites 

Before embarking on this journey, ensure you have the following prerequisites in place:

  1.      A Jenkins server up and running.

 2.     Docker installed on both the Jenkins server and the machine you intend to use as a Docker host.

 3.     SSH access configured between the Jenkins server and the Docker host.

 4.    Java should be installed on your agent server.

Step 1: Set Up Jenkins

Open your Jenkins dashboard and navigate to "Manage Jenkins."

Click on "Manage Nodes "

Select "New Node" to create a new Jenkins agent.

Provide a name for the agent and choose "Permanent Agent."

In the configuration, specify the following:

•        Remote root directory: Choose a directory on the Docker host where Jenkins agents will be launched.

•        Labels: Assign labels to the agent for identification.

Related Article :  HOW TO INSTALL AND USE DOCKER : Getting Beginner

Select Manage Jenkins --> Credentials --> system --> Global unrestricted --> add credentials 

Input the ip addres of the  docker host

• Usage : Select Usage this is node much as possible  for node ssh
• Lauch Method : Select agent ssh for add node  docker with ssh agent
• Host  :  Input IP ADDRESS OR Hostname Docker Host 
• Credentials :   Select Credentials for docker host. 

 Save the configuration.

Related Articel :  How to Install Kubernetes on Ubuntu 20.04

Step 2 : Create user  jenkins  and install java for docker host

Add user jenkins in docker host

#  adduser jenkins

Add entri file  below this paragraph  in visudo

# Allow members of group sudo to execute any command

%sudo   ALL=(ALL:ALL) ALL

jenkins ALL=(ALL) NOPASSWD: ALL

# See sudoers(5) for more information on "@include" directives:

Install package java for  requiretment jenkins agent 

# sudo apt install default-jre -y

Verify java version 

# java --version

openjdk 11.0.21 2023-10-17

OpenJDK Runtime Environment (build 11.0.21+9-post-Ubuntu-0ubuntu122.04)

OpenJDK 64-Bit Server VM (build 11.0.21+9-post-Ubuntu-0ubuntu122.04, mixed mode, sharing)

Step 3 :  Install Docker  Plugin

 

In the Jenkins dashboard, navigate to "Manage Jenkins" > "Manage Plugins." >> Select Plugins --> Install

Select  Plugin this below : 

CloudBees Docker Build and Publish plugin Version 1.4.0

CloudBees Docker Custom Build Environment Plugin Version 1.7.3

CloudBees Docker Hub/Registry Notification Version 2.7.1

Docker

Step 4:  CI/CD : Automation Deploy Application HTML Using Jenkins

Fantastic! Adding a Docker node is a great step. Now, let's dive into deploying that simple HTML application via Jenkins. Here's a brief guide for you:

Prerequisites 

1. Docker Hub 
2. Jenkins Server is running 
3. Dockerfile
4. Jenkinsfile

Absolutely, adding Docker Hub credentials to Jenkins is a smart move for secure and seamless integration.

Add  Credentials for docker hub 

Example Dockerfile  

FROM nginx:latest

COPY ./html/. /usr/share/nginx/html/.

EXPOSE 80

Example Jenkinsfile 

pipeline {

    agent any

    stages{

        stage("checkout"){

            steps{

                checkout scm

            }

        }

        stage("Build Image"){

            steps{

                sh 'sudo docker build -t webserver-devopsgol-betahjomblo:1.0 .'

            }

        }

        stage('Docker Push') {

            steps {

                withCredentials([usernamePassword(credentialsId: 'docker_cred', passwordVariable: 'DOCKERHUB_PASSWORD', usernameVariable: 'DOCKERHUB_USERNAME')]) {

                    sh 'sudo docker login -u $DOCKERHUB_USERNAME -p $DOCKERHUB_PASSWORD'

                    sh 'sudo docker tag webserver-devopsgol-betahjomblo:1.0 adinugroho251/webserver-devopsgol-betahjomblo:1.0'

                    sh 'sudo docker push adinugroho251/webserver-devopsgol-betahjomblo:1.0'

                    sh 'sudo docker logout'

                }

            }

        }

      stage('Docker RUN') {

          steps {

           sh 'sudo docker run -d -p 80 --name webserver-betahjombloterus  adinugroho251/webserver-devopsgol-betahjomblo:1.0'

      }

    }

 }

}

    

For detail  projects simple html : https://github.com/devopsgol/apps-html

Add Job in Jenkins  for CI/CD 

Select Restrict where this project can be run  for remote docker host  and input label docker agent ssh. 

Select Source code Manangement  and  input source code project. example for a github.

Checklist  Pool  SCM  for automation deploy using jenkins. When there's a code change from the Source Code Management (SCM) like GitHub or the latest commit changes, Jenkins will trigger to perform the build and deploy.

Select  Build Steps --> Execute Shell 

Certainly! Here's the command to build the container:

imageName=web-devopsgol:${BUILD_NUMBER}

containerName=webserver-betahjombloterus 

sudo docker build -t $imageName .

sudo docker run -p 3000:3000 -d --name $containerName $imageName

Save Configuration  

Click Build Now  for running is job

Logs for job pipelines jenkins

Alhamdulilah container is running and successfuly curl in services application. 

Conlusion 

Congratulations! You have successfully integrated Docker and SSH for Jenkins agents, enhancing the scalability and flexibility of your CI/CD pipelines.

If you want to read more insightful tutorials and articles related to DevOps, feel free to visit The Insider's Views.

In this article, we will delve into Docker from the basics to becoming proficient.

Let's embark on our journey into the world of containerization with a deep understanding of Docker for beginners.

What is Docker?

Before we go any further, let's collectively understand what Docker actually is.

For beginners, Docker is an open-source platform that allows developers to package, ship, and run applications using containers.

These containers help ensure that applications run consistently across various environments.

 

Benefits of Using Docker for Beginners

 

It is essential for beginners to grasp the benefits of using Docker. From space efficiency to ensuring application portability, Docker provides a range of advantages that make it worthwhile to learn.

1.   Space Efficiency:

Docker enables users to package all application dependencies into a container, reducing file size and making application management more efficient.

   2. Incredible Portability:

One of the many reasons people switch to Docker is its incredible portability. Containerized applications can run in various environments without worrying about configuration.

 

Prasyarat

 To follow this tutorial, you'll need the following:

• Ubuntu 20.04 server configured by following the initial server setup guide for Ubuntu 20.04, including firewall configuration and a non-root sudo user.
• An above account is required Docker Hub if you want to create your own image and upload it to Docker Hub, as demonstrated in steps 7 and 8.

 

Step 1  - Install Package Docker

 

The Docker package is available in the official Ubuntu repositories but may not be the latest version. To get the latest Docker packages, we recommend using the official Docker repository.

To do this, we will add the latest package source, add the Docker GPG key to ensure valid downloads, then install the package.

First, update your existing package list;

Moving on, install some prerequisite packages using the apt command.:

Add the GPG key from the Docker official repository to your operating system.

Add repository docker 

After adding the repository, update all your packages first.

Now, installing package docker

Once you've successfully installed , you can verify it using the command docker version.

After successfully installing Docker, you can check whether the Docker service is running or not. You can use the command systemctl for this.

To ensure that the Docker service starts automatically when the server restarts, you can follow the command below:

Related Article : Navigating the DevOps Landscape: A Journey Through Essential Tools

Step 2 :  Use Command Docker without sudo

By default, Docker commands can only be executed by the root user or a user who has been added to the docker group. If you want to avoid typing sudo every time you run a Docker command, you can add your user to the docker group.

After successfully adding your user to the docker group, you can perform verification.

Step 3 :  Using Docker Command

Docker involves passing a series of options from a command followed by arguments. You can use the following command:

You can see the docker command

To be able to view information about Docker system-wide, you can use the following command: 

Let's explore some of these commands. We will start learning with pictures.

Step 4 :  Use Docker Images

Docker containers are created from Docker images. By default, Docker pulls images from Docker Hub as a Docker registry managed by Docker.  Anyone can host their Docker images on Docker Hub. Most applications and Linux distributions you need have images stored there.

To check if you can access and download images from Docker Hub, enter:

Initially, Docker couldn't find the local ubuntu image so it downloaded the image from Docker Hub, which is the default repository. Once the image is uploaded, Docker creates a container from the image and the application inside that container runs and displays a notification.

Run the following command to download the official Ubuntu image to your computer:

As you'll see later in this guide, the image you use to run your container can be modified and used to create a new image, which can then be uploaded (push is the technical term). algorithm) to Docker Hub or other Docker registries.

Let's take a closer look at how to run containers.

Step 5 : Running a Docker Containers

 The Ubuntu container you ran in the previous step is an example of a container that runs and exits after issuing a test message.  Containers can be much more useful than that, and they can be interactive. After all, they are similar to virtual machines but are more resource efficient.

For example, let's run a container using the latest Ubuntu image. Combining the -i and -t switches will give you interactive access to the shell in the container: 

Your command prompt will change to reflect the fact that you are now working inside the container and will look like this:

Note the container ID in the command prompt. In this example it is 837150bda6c1. You will later need this container ID to identify the container when you want to delete it. Now you can run any command inside the container. For example, check os-release inside the container:

Let's take a closer look at how to use external storage local.

Related Article : How to Install Kubernetes on Ubuntu 20.04

Step 6 :  Use External Storage

By default, data in Docker containers is not persistent. This means that when the container is destroyed, so is the data. There may be cases where you want to retain data beyond the life of the container, and this can be achieved using persistent data storage. 

The two persistent data storage options available with Docker are volumes and link mounts.

Volumes are preferred for persistent data management because it is created and managed by Docker , thus separate from the core functionality of the server.  Volumes can be stored in a Docker-managed portion of the host file system (/var/lib/docker/volumes/), on remote servers, or on cloud providers, and yield better performance than linked drives.

With linked drives, data on the server is mounted into a container. This process relies heavily on the host having a specific file structure, thus providing limited functionality compared to volumes. In the next sections, we will create volumes, Move data to these drives and mount or attach the drives to the enclosure.

 Create file example  for test storage persistent docker 

Running container with mounting the directory above on {mnt}

Output 

Let's take a closer look at how to use external storage NFS

Step 7 :  Use External Storage ( NFS ) 

So, you've decided to dive into the vast ocean of Docker, and now you're wondering how to hook up external storage using NFS, huh? Well, buckle up, my friend, because I'm about to guide you through this wild ride in the simplest way possible!

Setting the Stage

Before we get our hands dirty, make sure you have Docker installed and a basic understanding of what NFS is. Now, let's roll!

Step 1: Install NFS-Server

First things first, Install nfs-server and  configured path nfs

Configure path storage  for nfs-share 

Step 2 : Create Docker volume

Generate docker  volume with nfs-server  

Output  after generate  docker  volume nfs-server 

Create a container  for  testing docker  volume  whit storage nfs 

Container is running well

Access the container by logging in. Execute the 'touch' command to create a file. The file should be created at the specified path, which is /data. The testing is specifically for checking the functionality of the NFS (Network File System) storage.

Let's take a closer look at how to use DockerFile generate image  

Step 8 :  Use DockerFile

In the ever-evolving landscape of software development, the utilization of containerization has become paramount. Docker, a leading platform for containerization, empowers developers to encapsulate their applications and dependencies into portable units known as containers. One of the key elements driving this efficiency is the Dockerfile.

Understanding the Dockerfile

A Dockerfile is like a recipe for creating a container. It consists of a set of instructions that Docker follows to build a container image. Absolutely, let's dive into a simple example of a Dockerfile for a Nginx 

application:

Build image from dockerfile

Output to Image docker 

Create a container after successfully creating image from Dockerfile 

Ensuring Your Container is Up and Running

test connection port from container 

Conclusion: Venture with Confidence!

Docker might seem intimidating at first, but with perseverance and improved understanding, you can overcome all obstacles. So, venture into the Docker world with confidence, making your applications more efficient and manageable.

FAQs (Frequently Asked Questions)

What is Docker?

Docker is an open-source platform for packaging, shipping, and running applications using containers.

How do I install Docker?

Visit the official Docker website and follow the provided installation guide.

Why is Docker important for beginners?

Docker provides space efficiency and incredible application portability, making it important for beginners.

What are the main benefits of using Docker?

Key benefits include space efficiency and incredible application portability. How to overcome difficulty understanding container concepts?

With time and practice, understanding of container concepts will improve.