Docker

What is Docker?

Docker is a platform for developing, shipping, and running applications. It allows developers to build, package, and distribute applications as containers. Containers are lightweight, standalone, and executable packages that include everything needed to run an application

Docker containers are similar to virtual machines, but they are more portable, efficient, and easy to use. They are isolated from each other and from the host system, and they share the same kernel.

What are the benefits of using Docker?

• Consistency: Docker containers provide a consistent environment for applications, regardless of the underlying infrastructure.
• Portability: Docker containers can run on any system that supports Docker, making it easy to move applications between environments.
• Scalability: Docker containers can be easily scaled up or down to meet the demands of the application.

What is a Docker image?

A Docker image is a lightweight, standalone, and executable package that includes everything needed to run an application. It contains the application code, runtime, libraries, and dependencies. Docker images are used to create Docker containers.

What is a Docker container?

A Docker container is a runtime instance of a Docker image. It is a lightweight, standalone, and executable package that includes everything needed to run an application. Docker containers are isolated from each other and from the host system, and they share the same kernel.

How to create a Docker image?

To create a Docker image, you need to write a Dockerfile, which is a text file that contains the instructions for building the image. The Dockerfile specifies the base image, the application code, runtime, libraries, and dependencies, and any other configuration settings.

Once you have written the Dockerfile, you can use the docker build command to build the image. For example:

docker build -t myapp .

This command builds the image using the Dockerfile in the current directory and tags it with the name myapp.

Kubernetes

What is Kubernetes?

Kubernetes is an open-source platform for automating, deploying, scaling, and managing containerized applications. It allows developers to build, ship, and run applications in a consistent and efficient manner.

Kubernetes provides a container-centric infrastructure that abstracts the underlying infrastructure and provides a consistent environment for applications. It automates the deployment, scaling, and management of applications, and it provides self-healing capabilities to ensure the availability and reliability of applications.

What are the benefits of using Kubernetes?

• Scalability: Kubernetes allows applications to be easily scaled up or down to meet the demands of the application.
• Availability: Kubernetes provides self-healing capabilities to ensure the availability and reliability of applications.
• Consistency: Kubernetes provides a consistent environment for applications, regardless of the underlying infrastructure.

What is a Kubernetes pod?

A Kubernetes pod is the smallest deployable unit in Kubernetes. It is a group of one or more containers that are deployed together on the same host. Pods are the basic building blocks of Kubernetes, and they are used to run, scale, and manage applications.

pod VS container

• A pod is a group of one or more containers that are deployed together on the same host.
• A container is a runtime instance of a Docker image.

What is a Kubernetes deployment?

A Kubernetes deployment is a resource object that provides declarative updates to applications. It allows you to define the desired state of the application, and Kubernetes will automatically manage the deployment to ensure that the application is running as expected.

How to deploy an Java application in Kubernetes?

To deploy an application in Kubernetes, you need to write a deployment configuration file, which is a YAML file that contains the specifications for the deployment. The deployment configuration file specifies the desired state of the application, including the number of replicas, the container image, and any other configuration settings.

Once you have written the deployment configuration file, you can use the kubectl apply command to apply the configuration to the Kubernetes cluster. For example:

kubectl apply -f deployment.yaml

helm chart

Helm is a package manager for Kubernetes that provides a way to define, install, and manage applications on Kubernetes. It allows you to define the desired state of the application, including the number of replicas, the container image, and any other configuration settings, and it provides a way to package and distribute applications as Helm charts. it’s an api object used to store non sensitive configuration

OpenShift

What is OpenShift?

OpenShift is a container platform that provides a developer-friendly environment for building, shipping, and running applications. It is built on top of Kubernetes and provides additional features and capabilities to simplify the development, deployment, and management of applications.

OpenShift provides a developer-friendly environment that abstracts the underlying infrastructure and provides a consistent environment for applications. It automates the deployment, scaling, and management of applications, and it provides self-healing capabilities to ensure the availability and reliability of applications.

What are the benefits of using OpenShift?

• Developer-friendly: OpenShift provides a developer-friendly environment for building, shipping, and running applications.
• Scalability: OpenShift allows applications to be easily scaled up or down to meet the demands of the application.

What is a OpenShift project?

A OpenShift project is a logical grouping of applications and resources within OpenShift. It provides a separate and isolated environment for applications, and it allows you to define the access control and resource quotas for the applications within the project.

What is a OpenShift deployment?

A OpenShift deployment is a resource object that provides declarative updates to applications. It allows you to define the desired state of the application, and OpenShift will automatically manage the deployment to ensure that the application is running as expected.

How to deploy an Java application in OpenShift?

To deploy an application in OpenShift, you need to write a deployment configuration file, which is a YAML file that contains the specifications for the deployment. The deployment configuration file specifies the desired state of the application, including the number of replicas, the container image, and any other configuration settings.