🧠 What is EXISTS? EXISTS is a logical operator in SQL that checks whether a subquery returns any rows. If the subquery returns at least one row, EXISTS evaluates to TRUE. If the subquery returns no rows, EXISTS evaluates to FALSE. It’s often used in a WHERE clause to test for the existence of…
Here’s a comprehensive guide to Docker container commands with explanations and examples. I’ll organize them by category so it’s easy to reference. 1. Running Containers CommandPurposeExampledocker run <image>Run a container from an imagedocker run nginxdocker run -d <image>Run container in detached mode (background)docker run -d nginxdocker run -it <image>Run container interactively with terminaldocker run…
Here’s a comprehensive list of Docker commands related to images, broken down by category, with explanations and examples: 1. Pulling and Searching Images CommandPurposeExampledocker pull <image>Download an image from a registry (e.g., Docker Hub)docker pull nginx:latestdocker search <image>Search for an image in Docker Hubdocker search postgres 2. Listing Images CommandPurposeExampledocker images or docker image…
A Secret in Kubernetes is an object that stores sensitive information such as passwords, tokens, SSH keys, or certificates, separate from application code. Unlike ConfigMaps, Secrets are intended for confidential data and can be handled more securely. ⚙️ Definition A Secret allows you to inject sensitive data into Pods without exposing it in container…
A ConfigMap in Kubernetes is an API object used to store non-confidential configuration data in key-value pairs, so you can separate configuration from application code. It allows you to dynamically configure your applications without rebuilding container images. ⚙️ Definition A ConfigMap provides a way to inject configuration data into Pods — such as environment…
A Kubernetes Ingress is an API object that manages external access to Services, typically HTTP and HTTPS traffic, providing routing, load balancing, SSL termination, and virtual hosting — all through a single external endpoint. Think of it as the entry point to your cluster’s web traffic. 🌐 ⚙️ Definition An Ingress exposes HTTP(S) routes…
A Service in Kubernetes is an abstraction that defines a stable network endpoint for accessing a set of Pods — even if those Pods change over time. Since Pods are ephemeral (they can be created, destroyed, or rescheduled), a Service provides a consistent way to reach them via a fixed IP address, DNS name,…
A Deployment in Kubernetes is a higher-level controller that manages ReplicaSets and provides declarative updates for Pods and applications. In simpler terms →👉 Deployment = Automated management + scaling + rolling updates for your Pods. ⚙️ Definition A Deployment defines the desired state of your application (like number of replicas, container image, etc.), and…
A ReplicaSet (RS) in Kubernetes ensures that a specified number of identical Pods are running at any given time.It’s one of the key controllers that manages Pod replication and availability. ⚙️ Definition A ReplicaSet is a Kubernetes controller that maintains a stable set of running Pods — it automatically adds or removes Pods to…
A Pod is the smallest and simplest deployable unit in Kubernetes. It represents one or more containers that share the same network, storage, and lifecycle. Let’s break it down clearly 👇 🧩 What Is a Pod? A Pod is a wrapper around one or more containers (usually Docker containers). Containers in a Pod: Share…