DEV Community: Yash Chaudhari

🤖 What is a Parameterized Job in Jenkins?

Yash Chaudhari — Sat, 02 Aug 2025 13:40:16 +0000

In Jenkins Parameterized Job is a type of job that allows us to select parameters while building the Jenkins Job.

There are various types of Parameters we can select.

For example - String, Choice, etc.

In this article, we are going to see how to make a Parameterized Jenkins Job.

1. Create a simple freestyle project.

2. Next, select the option - This project is parameterized, and click on Add Parameter.

3. Then, select the parameter type that you want to add.

4. Add the name of the parameter with a default value.

5. Next, in the Build steps section, select the Execute Shell option and add this command

echo $Param1

6. Click on save and Build the Project. You will see Build with Parameters option. Click on that.

7. After clicking on the Build with Parameters option. Add the parameter value that you want to pass. In my case, I have passed "This is a Parameterized Jenkins Job". After that, click on Build.

8. Check the Console Output of the Job.

Use Cases -

When we need to pass the values just before the job build, then we can pass the values.
For example, if we are installing different versions of the software. So, we can pass the version of the software as a parameter.
If there's a need that we have to pass the commands at run time. So, we can use this option.

Building Blocks of Docker: Understanding Images

Yash Chaudhari — Tue, 15 Apr 2025 13:53:33 +0000

Docker is widely used to containerize applications. There are also other containerization platforms such as Containerd, Rkt (Rocket), etc., but Docker is dominating the market.

In this article, we will see what is Docker image?, the layers of a Docker image, and how to write a custom Docker image.

• What is Docker Image?

Docker Image is like a readymade template. It contains predefined code, libraries that help you to create containers. All are combined in a single file. So, there's no need to create an explicitly environment because that Docker Image is providing you that type of environment. So just need to run the Docker Image that's it.

Remember 📝 -

The Docker Image is written in a file that does not have an extension, and the name of that file is Dockerfile.
Remember the hierarchy -

Dockerfile creates a Docker Image
Docker Image creates a container

Before going to understanding the layers of a Docker Image, let's see what exactly the Dockerfile looks like.

FROM openjdk:17-slim

WORKDIR ./app

COPY . .

RUN javac HelloWorld.java

CMD ["java", "HelloWorld"]

The above code is the simple Docker Image code, which will create a java image with the Hello World Program. So, when we create the container from this image, we will be able to see the output.

• What are layers in Docker Image

Every line in the Dockerfile acts as a layer for the Docker Image

From the above code, let's break it down.

FROM openjdk:17-slim

This line acts as a base layer for the Docker Image. On the above, those remaining lines will execute. In some Docker Images, the base layer is ubuntu also. In our case, it is OpenJDK.

WORKDIR ./app

This line is the working directory for the Dockerfile. It will create a working directory where all the files related to the Dockerfile will be stored. This line will act as a second layer for the Docker Image.

COPY . .

This line will copy all the files in the working directory that are required to create the Docker Image. This is the third layer for the Docker Image.

RUN javac HelloWorld.java

After copying all the files in the working directory, this line will execute, and the Docker Image will be created. This is the fourth layer for the Docker Image.

CMD ["java", "HelloWorld"]

This line will execute during container creation. It is the fifth layer for the Docker Image.

Now, let's create a Docker Image of the Simple Java Hello World Program from the code which is mentioned above.

Command to create a Docker Image

docker build -t java-image .

Docker Image has been created.

Lastly, let's create a container. So, we will be able to see the output of the Java Code.

In this way, we have seen each layer of the Docker Image.

Simple Pod YAML file in K8s for beginners

Yash Chaudhari — Tue, 15 Apr 2025 11:35:30 +0000

In Kubernetes, YAML files play a significant role not just in Kubernetes but also in Ansible, Docker Compose etc. Many beginners are in question about how to write YAML files for pods. In this article we will see how to write a simple YAML file for pods.

First of all, remember 4 things while writing YAML files for pods

What are they? 🤓

They are as follows -

apiVersion
kind
metadata
spec

1. apiVersion

In Kubernetes, there are many Kubernetes objects such as pod, deployment, cronjob, etc. So, apiVersion indicates the Kubernetes API version for creating pods. The image shown below displays different API versions for Kubernetes objects.

2. kind

The kind field denotes which Kubernetes object will create.

3. metadata

The metadata includes the data about Kubernetes objects which is going to be created, like name, labels, etc.

4. spec

The spec denotes what will be included inside the pods after creation.
For example - Containers.

Now, let's see a simple YAML file for creating pods.

apiVersion: v1
kind: Pod
metadata:
  name: first-pod-01
spec:
  containers:
    - name: nginx
      image: nginx

In the above YAML file, all the 4 things are mentioned, which we have seen above.

After running the kubectl apply -f <YAML file name>, the pod will be created.

Note - Image I have used to show API versions of different Kubernetes object from this link.

Step-by-Step Guide to Changing File Permissions in Linux 🐧

Yash Chaudhari — Fri, 11 Apr 2025 14:15:05 +0000

In Linux, there are many files and directories that belong to different users and different groups, but how to check permissions for those files? So, for this, there is a command that lists down the files and directories with their permissions and owners.

The command is -

ls -l

For example -

🤔 But again, there's a question what is written there before any filename or directory name?

The answer is that it denotes the type (is it file or directory) with their permissions such as users, groups and others

Let's break it down -

drwxr-xr-x 1 root root 4096 Apr 11 08:31 apt

First letter d means it is a directory and if it is file then it will be denoted with - sign

For example -

-rw-r--r-- 1 root root   98 Nov 22 03:45 shells.state

Now, the next 9 letters are divided into three categories

Owners, Groups and Others and that rwx letters indicates

r - read
w - write 
x - execute

For example -

Now, all permissions, such as read, write, and execute have their own Octal Coding System. It means they have assigned with octal codes

Permission   Symbol  Value
Read           r       4
Write          w       2
Execute        x       1

If we are assigning the permissions to users, groups or others with the help of octal values then we have to sum up their values.

For example, I want to assign full permission to users, groups and others then, the values will be -

4 (Read) + 2 (Write) + 1 (Execute) = 7 For Users

4 (Read) + 2 (Write) + 1 (Execute) = 7 For Groups

4 (Read) + 2 (Write) + 1 (Execute) = 7 For Others

Then, the final code will be 777.

2nd Example - I only want to assign read permission to users and groups then, the values will be -

4 (Read) + 0 (Write) + 0 (Execute) = 4 For Users

4 (Read) + 0 (Write) + 0 (Execute) = 4 For Groups

0 (Read) + 0 (Write) + 0 (Execute) = 0 For Others

Then, the final code will be 440

3rd Example - I want to assign execute permission to users and read permission to groups then, the values will be -

0 (Read) + 0 (Write) + 1 (Execute) = 1 For Users

4 (Read) + 0 (Write) + 0 (Execute) = 4 For Groups

0 (Read) + 0 (Write) + 0 (Execute) = 0 For Others

Then, the final code will be 140

Now, how to change the file permissions?

For example- The File shown below has some permission

-rw-r--r-- 1 root root 0 Apr 11 14:00 sample

I want to change the file permission and want to assign execute permission to groups and others

So, the Octal code will be -

0 (Read) + 0 (Write) + 0 (Execute) = 0 For Users

0 (Read) + 0 (Write) + 1 (Execute) = 1 For Groups

0 (Read) + 0 (Write) + 1 (Execute) = 1 For Others

The final code will be 011

Command to change file permissions -

chmod <octal_code> <filename/dir. name>

chmod 011 sample

After giving the command, the permissions have changed

------x--x 1 root root 0 Apr 11 14:00 sample