Notes

1) Where do you store binaries in Git?
It’s generally not recommended to store binaries directly in Git repositories due to increased repository size and potential versioning issues. Instead, use Git LFS (Large File Storage) for managing large files like binaries.

2)Where do you store the source code?
In Git, the source code is typically stored in a repository. The repository can be hosted on platforms like GitHub, GitLab, Bitbucket, or it can be local on your machine. The actual source code files are organized within the repository’s directory structure.

3)What is git and why we need it?
Git is a distributed version control system used for tracking changes in source code during software development. It allows multiple developers to collaborate on a project by managing different versions of the codebase. Git provides features like branching, merging, and history tracking, enabling efficient collaboration, version management, and code stability. It’s essential for team-based development to maintain a structured and organized code development process.

4)What is git repository and what is branch and how many types of branches are there in git?
A Git repository is a version control system that tracks changes in files and manages collaborative development. A branch in Git is a parallel version of the code within a repository, allowing for independent development and experimentation.

There are two main types of branches in Git: local branches and remote branches. Local branches exist only on your local machine and are used for your personal development. Remote branches are stored on a remote repository and enable collaboration between team members.

Additionally, branches can be categorized into feature branches, release branches, and hotfix branches based on their purposes in the development workflow.

5)How can you restore your last 3rd committed version?
Restoring a specific version in version control systems like Git involves using the commit hash associated with that version. You can use the “git reset” or “git checkout” command followed by the commit hash to revert to the desired version. Make sure to create a backup or branch before making such changes to avoid data loss.

6)How to check the IP address, RAM, CLU utilisation, memory and how many files are associated with server?
To check the IP address, use the command “ifconfig” or “ipconfig” in the terminal or command prompt, depending on your operating system.

For RAM and CPU utilization, you can use the “top” or “htop” command on Unix-based systems (Linux, macOS) and “Task Manager” on Windows.

To check memory usage, you can use the “free” command on Unix-based systems or check the “Memory” tab in Task Manager on Windows.

To find the number of files associated with the server, you can use the “ls” command on Unix-based systems, or “dir” on Windows, within the directory you want to inspect. Additionally, tools like “find” can help recursively count files.

Keep in mind that specific commands might vary depending on your operating system and distribution.

7)How to get disk attached information in linux
You can use the lsblk command to list information about block devices, including disks and their partitions, in Linux. Additionally, you can use the fdisk -l command for a more detailed view of disk information.

8) Swap, ulimit, resource utilisation
Swapping occurs when the operating system moves data between RAM and the swap space on disk. “ulimit” is a command that sets or displays user-level resource limits. Monitoring resource utilization helps ensure optimal system performance.

9) Variables in docker and how to declare them
In Docker, you can use environment variables to configure and customize container behavior. You declare them in your Dockerfile or when running a container.

1. In Dockerfile:
• Use the ENV instruction to set environment variables.

ENV MY_VARIABLE=my_value


2. During Container Run:
• Use the -e option with docker run to set environment variables.

docker run -e MY_VARIABLE=my_value my_image


3. Docker Compose:
• In a docker-compose.yml file, use the environment key.

version: '3'
services:
my_service:
image: my_image
environment:
MY_VARIABLE: my_value



Environment variables provide a flexible way to configure containers without modifying the underlying image.

10)how to start multiple containers at a time?
To start multiple containers simultaneously, you can use the docker-compose tool. Here’s a basic example:

1. Create a docker-compose.yml file:

version: '3'
services:
web:
image: nginx:latest
ports:
- "8080:80"
db:
image: postgres:latest
environment:
POSTGRES_PASSWORD: example

1. This example defines two services (web and db).
2. Run the containers using docker-compose:

docker-compose up -d

2. The -d flag runs the containers in the background.

This will start both the web and db containers defined in the docker-compose.yml file. Adjust the file according to your specific needs and add more services as necessary.

Remember, you need to have Docker Compose installed. If it’s not installed, you can follow the instructions on the official Docker Compose installation guide.

11)What is docker Compose?
Docker Compose is a tool for defining and running multi-container Docker applications. It allows you to describe the services, networks, and volumes for a set of Docker containers in a YAML file, making it easier to manage and deploy complex applications with multiple components.

12)Where do you store docker files and images
Docker files, which are used to build Docker images, are typically stored in your project directory. Docker images are stored in a registry, such as Docker Hub, unless specified otherwise. During development, images may be stored locally on your machine.

13) How to integrate docker with Jenkins
To integrate Docker with Jenkins, you can follow these general steps:

1. Install Docker on Jenkins Server:
Ensure Docker is installed on the machine running Jenkins. You can install Docker using the official Docker installation guide.
2. Install Docker Plugin in Jenkins:
In the Jenkins web interface, navigate to “Manage Jenkins” > “Manage Plugins.” Install the “Docker” plugin. This plugin enables Jenkins to interact with Docker, allowing you to build and publish Docker images.
3. Configure Jenkins Global Tool Configuration:
In Jenkins, go to “Manage Jenkins” > “Global Tool Configuration.” Add Docker as a global tool, specifying the Docker installation location.
4. Create or Modify Jenkins Job:
Open or create a Jenkins job for your project. In the job configuration, you’ll need to set up the following:
• Source Code Management:
Configure your version control system (e.g., Git).
• Build Environment:
Check the “Build inside a Docker container” option. Specify the Docker image you want to use for the build. This image should include the necessary build dependencies.
• Build Steps:
Define build steps as needed, which may include Docker-related commands like building and pushing Docker images.
5. Configure Docker Credentials:
If your Jenkins job involves pushing Docker images to a registry, you’ll need to configure Docker credentials. Navigate to “Manage Jenkins” > “Manage Credentials” and add your Docker Hub or registry credentials.
6. Save and Run Jenkins Job:
Save your Jenkins job configuration and run the job. Jenkins should now build your project within a Docker container, allowing for consistency and reproducibility.

Ensure you have the necessary permissions and security considerations in place, especially when dealing with Docker credentials.

These are general steps, and details may vary based on your specific project requirements and Jenkins setup.

14) How to mount the volumes in container
To mount volumes in a Docker container, you can use the -v or --volume option when running the docker run command. Here’s a basic example:

docker run -v /host/path:/container/path -it my_image

Explanation:

• -v or --volume: Specifies the volume to mount.
• /host/path: The path on the host machine where the volume will be mounted.
• /container/path: The path inside the container where the volume will be mounted.
• -it: This option is used to run the container interactively.

For example, let’s say you have a directory called my_data on your host machine, and you want to mount it to /data inside the container. The command would look like this:

docker run -v /path/to/my_data:/data -it my_image

This will mount the my_data directory from your host machine into the /data directory inside the running container.

You can also use named volumes or anonymous volumes for more flexibility. Here’s an example using a named volume:

docker run -v my_volume:/data -it my_image

In this case, Docker will create a named volume called my_volume and mount it to /data inside the container.

Remember to adjust paths and volume names based on your specific setup and requirements.

15) Few commands in docker and explain them

Certainly! Here are a few common Docker commands along with brief explanations:

1. docker run:
• Usage: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
• Explanation: Creates and starts a new container based on the specified image. You can also provide additional options, environment variables, and specify the command to run inside the container.
2. docker ps:
• Usage: docker ps [OPTIONS]
• Explanation: Lists the running containers. The -a option can be added to show all containers, including those that are stopped.
3. docker build:
• Usage: docker build [OPTIONS] PATH | URL | -
• Explanation: Builds a Docker image from a Dockerfile located at the specified path or URL. The . at the end indicates the current directory.
4. docker images:
• Usage: docker images [OPTIONS] [REPOSITORY[:TAG]]
• Explanation: Lists the available Docker images on your machine. You can filter by repository and tag if needed.
5. docker pull:
• Usage: docker pull [OPTIONS] NAME[:TAG|@DIGEST]
• Explanation: Downloads a Docker image from a registry. If you try to run a container with an image that isn’t available locally, Docker will automatically pull it.
6. docker exec:
• Usage: docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
• Explanation: Runs a command inside a running container. Useful for executing commands or debugging within a running container.
7. docker stop:
• Usage: docker stop [OPTIONS] CONTAINER [CONTAINER...]
• Explanation: Stops one or more running containers. It sends a SIGTERM signal, allowing processes inside the container to gracefully shut down.
8. docker rm:
• Usage: docker rm [OPTIONS] CONTAINER [CONTAINER...]
• Explanation: Removes one or more containers. The -f option can be added to force removal, even if the container is running.
9. docker-compose up:
• Usage: docker-compose up [OPTIONS]
• Explanation: Uses a docker-compose.yml file to start services defined in the file. Useful for multi-container applications.
10. docker network ls:

• Usage: docker network ls [OPTIONS]
• Explanation: Lists Docker networks

16) What is ansible playbook

An Ansible playbook is a script that defines a set of tasks to be executed on remote systems managed by Ansible. Ansible is an open-source automation tool that simplifies configuration management, application deployment, and task automation. Playbooks are written in YAML format, making them easy to read and write.

Here are key components and characteristics of an Ansible playbook:

1. YAML Format:
• Playbooks are written in YAML (YAML Ain’t Markup Language) format, which is human-readable and requires minimal syntax. The structure is hierarchical, and indentation is crucial.
2. Play:
• A play is the highest-level structure in a playbook. It consists of a set of tasks to be executed on a defined set of hosts. A playbook can contain one or more plays.
3. Hosts:
• Specifies the target hosts or servers where the tasks in a play should be executed. You can define hosts using inventory files or dynamic inventories.
4. Tasks:
• Tasks are individual units of work in a playbook. Each task typically represents a specific action or command that should be executed on the target hosts.
5. Modules:
• Ansible modules are pre-built units of code that perform specific tasks. Playbook tasks use modules to interact with the target system. Modules are idempotent, meaning they have the same

17) why we need ansible playbook

Ansible playbooks are essential for several reasons in the context of IT automation and configuration management:

1. Automation:
• Playbooks allow you to automate complex and repetitive tasks, reducing the manual effort required for configuration, deployment, and maintenance of systems.
2. Consistency:
• Playbooks provide a consistent way to define and enforce configurations across multiple servers. This consistency helps avoid configuration drift and ensures that all systems are in the desired state.
3. Repeatability:
• By defining tasks in playbooks, you can reproduce the same configuration on multiple systems or environments. This repeatability is crucial for development, testing, and deployment processes.
4. Idempotence:
• Ansible modules, used within playbooks, are designed to be idempotent. This means that running the same playbook multiple times has the same result, ensuring predictable outcomes and minimizing unintended changes.
5. Scalability:
• Playbooks are scalable and can be applied to a single server or a large infrastructure. This makes them suitable for managing diverse environments, from small setups to complex, distributed systems.
6. Documentation:
• Playbooks serve as documentation of your infrastructure as code. By examining a playbook, you can understand the steps taken to configure a system, making it easier to collaborate with team members and troubleshoot issues.
7. Modularity:
• Playbooks support the use of roles, allowing you to organize and reuse code. This modularity enhances maintainability, as changes or updates can be made to individual roles without affecting the entire playbook.
8. Version Control:
• Playbooks can be version-controlled using tools like Git. This enables tracking changes over time, collaborating with others, and rolling back to previous versions if necessary.
9. Orchestration:
• Playbooks facilitate the orchestration of complex tasks across multiple servers. You can define dependencies between tasks, control the order of execution, and handle conditional scenarios.
10. Extensibility:
• Ansible playbooks are extensible and can integrate with various modules, plugins, and external scripts. This flexibility allows you to tailor your automation to specific requirements.

In summary, Ansible playbooks are a powerful tool for automating, managing, and documenting the configuration of IT infrastructure. They contribute to efficiency, reliability, and maintainability in the ever-evolving landscape of system administration and DevOps practices.

18) What is CI/CD

CI/CD stands for Continuous Integration and Continuous Delivery (or Continuous Deployment), and it refers to a set of modern software development practices that aim to improve the development, testing, and delivery of software.

1. Continuous Integration (CI):
• Objective: Frequently integrate code changes into a shared repository.
• Process:
• Developers regularly commit code changes to a version control system (e.g., Git).
• Automated builds and tests are triggered whenever new code is committed.
• Integration issues are identified and resolved early in the development process.
2. Continuous Delivery (CD):
• Objective: Ensure that software is always in a deployable state.
• Process:
• Automated deployment pipelines are set up to move code changes through various stages (e.g., development, testing, staging) automatically.
• Code is automatically tested at each stage, and if all tests pass, the software is considered deployable.
• Manual

19)How to integrate Bit bucket and jfrog to Jenkins

Integrating Jenkins with Bitbucket and JFrog Artifactory involves setting up webhooks, configuring credentials, and creating Jenkins jobs. Here are high-level steps for each integration:

Jenkins with Bitbucket Integration:

1. Install Jenkins:
• Install Jenkins on a server or machine. Follow the official Jenkins installation guide for your environment.
2. Install Jenkins Plugins:
• Install the necessary Jenkins plugins for Bitbucket integration. You may need plugins like “Bitbucket Branch Source” and “Bitbucket” or equivalent.
3. Create Jenkins Job:
• Create a new Jenkins job and configure it to use the Bitbucket repository as the source. Use the “Bitbucket Team/Project” source type if you want to build branches and pull requests automatically.
4. Webhook Configuration in Bitbucket:
• In Bitbucket, go to your repository settings.
• Set up a webhook that points to your Jenkins server. The webhook should trigger on events like pushes or pull requests.
5. Configure Jenkins Credentials:
• If your Jenkins job needs credentials to access the Bitbucket repository, configure them in Jenkins using the “Credentials” section.

Jenkins with JFrog Artifactory Integration:

1. Install JFrog Artifactory:
• Install JFrog Artifactory on a server. Follow the official Artifactory installation guide for your environment.
2. Install Jenkins Plugins:
• Install the necessary Jenkins plugins for Artifactory integration, like “Artifactory Plugin.”
3. Configure Jenkins Global Tool Configuration:
• In Jenkins, go to “Manage Jenkins” > “Global Tool Configuration.” Add the JFrog CLI tool if required by your build process.
4. Create Jenkins Job:
• Create a new Jenkins job and configure it to build your project. If you use Maven, Gradle, or another build tool, configure the build steps accordingly.
5. Configure Artifactory Integration:
• In your Jenkins job configuration, add the Artifactory server details, including the URL and credentials. Specify the repository where artifacts should be deployed.
6. Webhook Configuration in Artifactory:
• Optionally, you can set up webhooks in Artifactory to trigger events based on artifact uploads. This is useful for additional automation or notifications.

Remember to secure your Jenkins server and credentials appropriately. Always follow best practices for securing your CI/CD environment.

These steps are general guidelines, and specifics may vary based on your project requirements and tool versions. Refer to the official documentation for Jenkins, Bitbucket, and JFrog Artifactory for detailed and up-to-date instructions.
------------------------------------------------------------------------------------------------------------------------------
20) Jenkins Pipeline
A Jenkins pipeline is a suite of plugins that allow you to define the entire software delivery process as code. It provides a way to express the process for building, testing, and deploying your applications in Jenkins, using a script-like syntax written in Groovy.

Key concepts in Jenkins Pipeline:

1. Pipeline Script:
• A pipeline script is a Groovy script that defines the entire build process. It can include stages, steps, and other constructs to describe the entire software delivery lifecycle.
2. Declarative vs. Scripted Pipeline:
• Jenkins supports both declarative and scripted pipeline syntax. Declarative pipeline is a more structured and simplified way of defining pipelines, while scripted pipeline offers more flexibility and is based on Groovy scripting.
3. Stages:
• A pipeline is divided into stages, each representing a phase in the software delivery process. Stages can include building, testing, deploying, and other activities.
4. Steps:
• Steps are individual tasks or commands within a stage. Each step represents a single action, such as running a script, invoking a build tool, or deploying artifacts.
5. Parallel Execution:
• Pipeline allows parallel execution of stages or steps, enabling concurrent processing and reducing overall build time.
6. Post Actions:
• Post actions define steps that should be executed after the completion of the pipeline, such as sending notifications, archiving artifacts, or triggering downstream jobs.
7. Pipeline as Code:
• Jenkins Pipeline treats the entire build process as code, stored alongside your application source code. This approach promotes version control and makes the build process more transparent and reproducible.
8. Integration with Version Control:
• Pipeline scripts can be stored in version control systems (e.g., Git) along with your application code. This allows changes to the build process to be tracked, reviewed, and versioned.
9. Pipeline Visualization:
• Jenkins provides a visual representation of your pipeline, showing the progress and status of each stage and step. This visualization aids in monitoring and troubleshooting.
10. Shared Libraries:
• Jenkins Pipeline allows the creation of shared libraries, which are reusable scripts and functions that can be shared across multiple pipelines, promoting code reuse and maintainability.

Example of a Declarative Jenkins Pipeline:

pipeline {
agent any

stages {
stage('Build') {
steps {
// Build your application here
}
}
stage('Test') {
steps {
// Run tests
}
}
stage('Deploy') {
steps {
// Deploy artifacts
}
}
}

post {
always {
// Post-build actions
}
success {
// Actions to take on success
}
failure {
// Actions to take on failure
}
}
}

Jenkins Pipeline provides a powerful and flexible way to define, manage, and visualize your software delivery process within Jenkins, making it suitable for complex and automated CI/CD workflows.

21) How many times can you trigger the build

The number of times you can trigger a build in Jenkins is not inherently limited by Jenkins itself. You can trigger builds as often as needed based on your development workflow and requirements. However, the frequency of triggering builds might depend on several factors:

1. Polling or Webhooks:
• If you are using polling to check for changes in your version control system (e.g., Git, SVN), the frequency of polling will determine how often Jenkins detects changes and triggers builds. Alternatively, using webhooks can enable more real-time triggering based on repository events.
2. Scheduled Builds:
• You can set up scheduled builds in Jenkins using cron-like syntax. Scheduled builds allow you to trigger builds at specific times, which can be useful for regular nightly builds or other planned intervals.
3. Manual Triggering:
• Builds can also be triggered manually by users through the Jenkins web interface or using tools like the Jenkins CLI. This gives you the flexibility to initiate builds on-demand.
4. Trigger Conditions:
• You can configure Jenkins jobs to trigger builds based on specific conditions, such as changes in a specific branch, the success or failure of other builds, or the presence of specific environment variables. This provides fine-grained control over when builds are triggered.

While Jenkins itself does not impose a strict limit on the number of builds you can trigger, it’s essential to consider the impact on your build infrastructure, resources, and overall build pipeline efficiency. Frequent builds, especially if resource-intensive, might strain your build environment and affect overall system performance.

It’s recommended to strike a balance between triggering builds frequently enough to catch issues early in the development process and avoiding unnecessary builds that might strain resources. Continuous Integration (CI) practices often involve triggering builds automatically upon code changes, ensuring that new code is regularly integrated and tested.

22) Terraform

Terraform is an open-source Infrastructure as Code (IaC) tool created by HashiCorp. It enables users to define and provision infrastructure using a declarative configuration language. Here’s a brief overview of key concepts and features:

1. Infrastructure as Code (IaC):
• Terraform allows you to describe your infrastructure using a declarative configuration language. This configuration is written in HashiCorp Configuration Language (HCL) or JSON.
2. Declarative Syntax:
• With Terraform, you declare what infrastructure components you need, and Terraform figures out how to create and manage them. This is in contrast to imperative approaches where you specify step-by-step instructions.
3. Providers:
• Terraform supports a wide range of cloud providers (AWS, Azure, Google Cloud, etc.), as well as various on-premises and SaaS services. Providers are plugins that allow Terraform to interact with specific infrastructure platforms.
4. Resources:
• In Terraform, resources represent the infrastructure components you want to manage. Examples include virtual machines, networks, databases, and more. Resources are declared in the Terraform configuration.
5. State Management:
• Terraform keeps track of the infrastructure state, which is a record of the resources it manages. The state file helps Terraform understand the existing infrastructure and determine what changes need to be applied.
6. Execution Plans:
• Before making any changes to the infrastructure, Terraform generates an execution plan. This plan outlines what actions Terraform will take to achieve the desired state, allowing users to review and approve changes before applying them.
7. Modularity:
• Terraform configurations can be organized using modules, which are reusable units of Terraform code. Modules enable better organization, sharing, and abstraction of infrastructure components.
8. Versioning and Collaboration:
• Terraform configurations can be versioned using version control systems (e.g., Git). This facilitates collaboration among team members and provides a history of changes.
9. Community and Ecosystem:
• Terraform has a vibrant community, and the HashiCorp Terraform Registry contains numerous pre-built modules and configurations that can be reused. This ecosystem accelerates infrastructure provisioning and management.
10. Extensibility:
• Terraform is extensible, allowing users to create custom providers or provisioners to integrate with specific services or systems that may not be supported out of the box.

Using Terraform, infrastructure can be provisioned, updated, and managed with consistency and repeatability. It is widely adopted in DevOps practices for automating the creation and maintenance of infrastructure, providing a foundation for Infrastructure as Code.

24)can we start terraform services in docker

Yes, you can run Terraform within a Docker container, which provides an isolated environment for running Terraform commands. This approach is useful for maintaining consistent dependencies and ensuring that the Terraform version and required tools are isolated from the host system. Here are the basic steps to run Terraform in Docker:

1. Create a Dockerfile:
Create a Dockerfile that specifies the base image, installs Terraform, and sets up any additional dependencies you might need.

# Use a base image with the desired Linux distribution
FROM ubuntu:latest

# Install required dependencies and Terraform
RUN apt-get update &&
apt-get install -y curl unzip &&
curl -fsSL https://releases.hashicorp.com/terraform/0.14.0/terraform_0.14.0_linux_amd64.zip -o terraform.zip &&
unzip terraform.zip -d /usr/local/bin/ &&
rm -f terraform.zip

# Set the working directory
WORKDIR /app

# Entry point for the Docker container
ENTRYPOINT ["terraform"]

1. Adjust the version number in the URL to match the desired Terraform version.
2. Build the Docker Image:
Build the Docker image using the Dockerfile.

docker build -t my-terraform-image .


3. Run Terraform Commands in a Container:
Once the Docker image is built, you can use it to run Terraform commands.

# Run a Terraform command within the Docker container
docker run -v $(pwd):/app my-terraform-image init
docker run -v $(pwd):/app my-terraform-image plan
docker run -v $(pwd):/app my-terraform-image apply

3. The -v $(pwd):/app option mounts the current directory into the /app directory within the container.

This setup allows you to encapsulate Terraform and its dependencies within a Docker container, providing a consistent and reproducible environment for running Terraform commands. You can then use this Docker image across different environments without worrying about host system dependencies.

25) Flavours of k8s and can we install k8s on baremetal

Kubernetes (K8s) has several distributions, often referred to as “flavors,” that cater to different use cases and preferences. Some popular Kubernetes distributions include:

1. Vanilla Kubernetes:
• Also known as upstream Kubernetes, it is the original, unmodified Kubernetes project. Users can install, configure, and manage it directly. However, this may require more manual effort.
2. Google Kubernetes Engine (GKE):
• Managed Kubernetes service provided by Google Cloud. GKE abstracts much of the underlying infrastructure, making it easier for users to deploy and manage applications without dealing with the complexities of cluster operations.
3. Azure Kubernetes Service (AKS):
• Similar to GKE but provided by Microsoft Azure. AKS is a managed Kubernetes service that simplifies the deployment, management, and scaling of containerized applications using Kubernetes.
4. Amazon Elastic Kubernetes Service (EKS):
• AWS-managed Kubernetes service. EKS abstracts the control plane and provides integrations with other AWS services, simplifying the deployment and operation of Kubernetes clusters on AWS.
5. Red Hat OpenShift:
• Kubernetes-based container platform with additional developer and operational tools. OpenShift adds features like source-to-image builds, integrated CI/CD, and enhanced security, making it more than just a Kubernetes distribution.
6. Rancher:
• An open-source container management platform that provides Kubernetes management along with additional features for managing and deploying containers across multiple clusters and environments.
7. k3s:
• A lightweight Kubernetes distribution designed for resource-constrained environments, edge computing, or situations where a minimal footprint is desired. k3s is optimized for simplicity and ease of use.

Regarding installing Kubernetes on bare metal, yes, it is possible to deploy Kubernetes clusters on bare-metal servers. Several tools and approaches facilitate this:

• kubeadm:
• kubeadm is a tool that automates the process of bootstrapping a Kubernetes cluster. It can be used to set up a Kubernetes cluster on bare metal by installing the necessary components.
• Kubespray:
• An Ansible-based tool that simplifies the deployment and management of Kubernetes clusters. Kubespray can be used to deploy clusters on various platforms, including bare metal.
• Minikube:
• While Minikube is primarily used for local development, it can also be configured to run on bare metal. Minikube creates a single-node Kubernetes cluster, suitable for testing and development purposes.

• MetalLB:
• A load balancer designed for bare metal Kubernetes clusters. MetalLB enables services with type LoadBalancer to work on bare metal by providing a load balancing solution.

When deploying Kubernetes on bare metal, considerations such as network configuration, load balancing, and storage need to be addressed. Tools like those mentioned above help streamline the process and manage the complexities associated with deploying Kubernetes on non-cloud environments.

26) how to deploy container in k8s what would you do if system crashes and how to restore all clusters

To deploy a container in Kubernetes (K8s), you typically create a Kubernetes Deployment or Pod configuration that specifies the container image, desired replicas, and other settings. Here’s a basic example using a Deployment:

1. Create a Deployment YAML file (e.g., my-deployment.yaml):

apiVersion: apps/v1
kind: Deployment
metadata:
name: my-app
spec:
replicas: 3
selector:
matchLabels:
app: my-app
template:
metadata:
labels:
app: my-app
spec:
containers:
- name: my-container
image: your-container-image:tag

1. This example deploys three replicas of a containerized application.
2. Apply the Deployment:

kubectl apply -f my-deployment.yaml

2. This command instructs Kubernetes to create the Deployment based on the configuration in the YAML file.

Now, if a system crashes or if you need to restore all clusters, you can follow these general steps:

1. Backup Kubernetes Resources:
• Regularly back up your Kubernetes resources, including Deployments, Services, ConfigMaps, and other essential objects. You can use tools like kubectl or specialized backup solutions for Kubernetes.
2. Persist Data Outside the Cluster:
• If your applications store data, consider using external databases or storage solutions to persist data outside the cluster. This ensures that even if the cluster is lost, critical data is preserved.
3. Use Infrastructure as Code (IaC):
• If you’ve defined your infrastructure using Infrastructure as Code (IaC) tools such as Terraform, ensure that the IaC code is versioned and backed up. This makes it easier to recreate the infrastructure in case of a failure.
4. Recreate the Cluster:
• If the entire cluster needs to be restored, use your IaC tool or the original provisioning method to recreate the Kubernetes cluster. This may involve reapplying Terraform configurations or using cloud provider-specific tools.
5. Restore Kubernetes Resources:
• Apply the previously backed-up Kubernetes resource configurations to restore the state of your applications. Use kubectl apply or a similar mechanism to recreate Deployments, Services, and other objects.

kubectl apply -f backup/my-deployment-backup.yaml


6. Validate and Monitor:
• Ensure that the restored cluster is functioning correctly. Monitor logs, check the status of Deployments, and verify that applications are running as expected.

By following these steps, you can recover from a system crash and restore your Kubernetes clusters, along with the deployed applications and configurations. Regular backups and a well-defined recovery process are crucial for maintaining resilience in a Kubernetes environment.