Networking

What are Unix Domain Sockets and How They Work When we think about communication between applications, we often imagine TCP or UDP over the network. But sometimes, processes don’t need to leave the machine at all. That’s where Unix Domain Sockets (UDS) come in. What is a Unix Domain Socket? A Unix Domain Socket is a special type of inter-process communication (IPC) mechanism in Unix-like systems. Instead of using IP addresses and ports, processes talk to each other via a file path on the filesystem (e.g., /var/run/docker.sock). ...

What is WebSocket? Normally, web communication works via HTTP. A client sends a request, the server responds, and the connection ends. But what if you need real-time updates — like in chat apps, online games, or stock tickers? Opening a new HTTP request for every update would be too slow and heavy. That’s where WebSocket comes in. Key Idea WebSocket creates a persistent, two-way connection between client and server. Instead of “ask and reply”, both sides can send messages anytime. It starts as an HTTP request, then “upgrades” the connection to WebSocket. Why WebSocket? Real-time communication (chats, notifications, multiplayer games). Efficiency — no need to reopen connections all the time. Bi-directional — both client and server can send data. Example in JavaScript // Client-side WebSocket const socket = new WebSocket("ws://localhost:8080"); // When connection opens socket.onopen = () => { console.log("Connected to server"); socket.send("Hello Server!"); }; // When message is received socket.onmessage = (event) => { console.log("Message from server:", event.data); }; On the server side (Node.js example with ws): ...

Kubernetes Flag: max-endpoints-per-slice Explained When Kubernetes services scale to hundreds or thousands of pods, managing their network endpoints efficiently becomes critical. This is where EndpointSlices come in. And one of the key tuning knobs for EndpointSlices is the max-endpoints-per-slice flag. What Is max-endpoints-per-slice? By default, Kubernetes groups pod endpoints into EndpointSlices (instead of one big Endpoints object). Each slice holds up to N endpoints (default: 100). The flag --max-endpoints-per-slice defines that maximum number. In simple words: it controls how many pod addresses go into a single EndpointSlice. ...

What is NodePort in Kubernetes? When you deploy an application in Kubernetes, by default it’s only accessible inside the cluster. To make it available outside, you need to expose it. One of the simplest ways to do this is with a NodePort service. How NodePort Works Kubernetes opens a port (30000–32767) on each node of the cluster. Any request sent to <NodeIP>:<NodePort> is forwarded to the service and then to the pods. Under the hood, it still uses ClusterIP, but adds an external entry point. So you can access your app like: ...

What is MetalLB? If you run Kubernetes in a cloud (AWS, GCP, Azure), creating a LoadBalancer service gives you an external IP automatically. But what if your cluster is bare metal — your own servers, without cloud integration? That’s where MetalLB comes in. MetalLB is a load balancer implementation for bare-metal Kubernetes clusters. It allows you to expose services of type LoadBalancer without relying on cloud providers. How MetalLB Works MetalLB assigns external IPs to services in one of two modes: ...