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A Public Subnet is a subnet that has a route to the internet through an Internet Gateway, allowing resources within it to be accessed from the internet. A Private Subnet, on the other hand, does not have a direct route to the internet, meaning resources in it cannot be accessed directly from the internet.

Auto Scaling is a feature in AWS that automatically adjusts the number of EC2 instances in a group based on demand, ensuring optimal performance and cost efficiency.

EC2, or Amazon Elastic Compute Cloud, is a web service that provides resizable compute capacity in the cloud, allowing users to run virtual servers and manage applications on-demand.

IAM (Identity and Access Management) in AWS is a service that allows you to manage users, groups, and permissions to securely control access to AWS resources.

AWS CLI (Amazon Web Services Command Line Interface) is a tool that allows users to interact with AWS services using command-line commands instead of the web-based console.

– **git add**: Stages changes in your working directory for the next commit.
– **git commit**: Records the staged changes in the repository's history with a message.
– **git push**: Uploads your local commits to a remote repository.

A commit in Git is a snapshot of changes made to the files in a repository. It contains the modified files, a unique identifier (hash), the author's information, a timestamp, and a commit message describing the changes.

`git fetch` downloads changes from the remote repository to your local repository but does not merge them into your working directory. `git pull` does both: it fetches the changes and then merges them into your current branch.

You can check the status of your Git repository by running the command `git status` in your terminal.

.gitignore is a file used in Git to specify which files or directories should be ignored by version control. It prevents certain files, like temporary files or sensitive information, from being tracked and included in commits.

A Pod in Kubernetes is the smallest deployable unit that can contain one or more containers, which share the same network namespace and storage resources.

A Service in Kubernetes is an abstraction that defines a logical set of Pods and a policy to access them. It enables communication between different components in a Kubernetes cluster.

The types of Services available in Kubernetes are:

1. **ClusterIP**: Exposes the Service on a cluster-internal IP. It is only accessible from within the cluster.
2. **NodePort**: Exposes the Service on each Node’s IP at a static port. It allows external access to the Service.
3. **LoadBalancer**: Creates an external load balancer in supported cloud providers, routing traffic to the NodePort.
4. **ExternalName**: Maps the Service to the contents of the externalName field (e.g., a DNS name), allowing access to external services.

Kubernetes handles networking and communication between pods using a flat network model where each pod gets its own IP address. Pods can communicate with each other directly using these IPs. Kubernetes also provides services, which are stable endpoints that can load balance traffic to pods, enabling communication between different services. Additionally, Kubernetes uses network plugins (CNI) to manage networking and enforce policies.

ConfigMaps and Secrets are Kubernetes objects used to manage configuration data.

– **ConfigMaps** store non-sensitive configuration data in key-value pairs, allowing applications to access configuration settings without hardcoding them in the application code. They can be used to inject environment variables, command-line arguments, or configuration files into pods.

– **Secrets** are similar to ConfigMaps but are specifically designed to store sensitive information, such as passwords, OAuth tokens, or SSH keys. Secrets are encoded and can be mounted as files or exposed as environment variables in pods, ensuring that sensitive data is handled securely.

Both are used to decouple configuration from application code, making applications more portable and easier to manage.

Kubernetes handles persistent storage using Persistent Volumes (PV), Persistent Volume Claims (PVC), and StorageClasses.

– **Persistent Volumes (PV)** are storage resources in the cluster that have been provisioned by an administrator or dynamically provisioned using StorageClasses.
– **Persistent Volume Claims (PVC)** are requests for storage by users, specifying size and access modes. When a PVC is created, Kubernetes finds a matching PV to bind to it.
– **StorageClasses** define different types of storage (like SSD or HDD) and allow dynamic provisioning of PVs based on the specified class.

This system allows for flexible and manageable storage solutions in Kubernetes.