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Podman and Linux Namespaces
by Shan Desai
Understand how podman works with configured Linux User Namespaces and how to configure / update these namespaces for current users.
Tutorials
Deep dives into DevOps and Server Side topics where theory blends with hands-on examples. You can try out commands from each tutorial in the attached remote playground, either from the browser or via SSH access from your local terminal — no extra setup required.
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A Practical Guide to SSH Tunnels: Local and Remote Port Forwarding
SSH port forwarding explained in a clean and visual way. How to use local and remote port forwarding. What sshd settings may need to be adjusted. How to memorize the right flags.
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eBPF and WASM - Better Together
Learn how Inspektor Gadget pairs eBPF with WASM to process kernel events—and walk through the same idea yourself by implementing a minimal example.
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Combining 2FA and Public Key Authentication for a better Linux SSH security
by med unes
Take a stock Debian SSH server and harden it the way you would in production: replace passwords with public-key auth, disable root login, add a TOTP second factor with PAM, and move off port 22, then prove it works by logging in, all inside the playground.
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Native SSH Reverse Tunneling with Pomerium
by Nick Taylor
Use Pomerium's native SSH support to publish a local service through a standard reverse SSH tunnel, with OpenID Connect (OIDC) authentication and continuous authorization on every request. Reach services behind Network Address Translation (NAT) without firewall holes or custom agents, and control both who can use the service and who can open the tunnel. Application traffic stays on infrastructure you control.
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How Servers Work: A Hands-On Introduction to TCP Sockets
Learn how servers actually work by building a tiny TCP server and client from scratch. A hands-on introduction to sockets, TCP, and the network programming model every backend, DevOps, and platform engineer should go through at least once.
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Getting started with Valkey on Architect
Learn how to run Valkey on spot instances without losing state
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How Container Registries Work: Pushing and Pulling Images By Hand
Container registries look simple until you need to debug what was actually pushed, why a pull picked the wrong image, or why deleting a tag didn't remove anything. Learn how registries work by pushing, pulling, inspecting, and deleting image data directly through the Registry API.
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What Is a Standard Container: Diving Into the OCI Runtime Spec
Are all containers just Linux processes? How does the OCI runtime specification define a container? What platforms do OCI containers support? What is a Docker container? Linux containers vs. Virtual Machine containers.
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Native SSH Access with Pomerium
by Nick Taylor
Pomerium can be used as a native SSH reverse proxy, adding OAuth authentication and flexible Pomerium policy enforcement to standard SSH connections, without the need for tunnels, or custom clients or servers.
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Building an eBPF/XDP NAT-Based (Weighted) Round Robin Load Balancer from Scratch
In this lab, you’ll build a NAT-based eBPF/XDP load balancer from scratch and implement both round-robin and weighted round-robin backend selection. Along the way, you’ll learn how to manage state in eBPF maps and distribute traffic across backends based on simple and capacity-aware scheduling strategies.
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Building an eBPF/XDP NAT-Based (Weighted) Least Connection Load Balancer from Scratch
In this lab, you will extend the eBPF/XDP-based NAT load balancer implementation with the least-connections to a weighted least-connections algorithm that accounts for backend capacity.
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Accelerating Transparent Ingress Proxy with eBPF and Envoy
This lab teaches you how to use eBPF socket acceleration to speed up communication between processes on localhost and optimize a transparent Envoy proxy setup. You will implement techniques that bypass parts of the kernel networking stack, allowing data to be transferred more directly between sockets to improve throughput and reduce latency.
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Getting Started with VictoriaMetrics on Kubernetes
Deploy VictoriaMetrics on Kubernetes using the VM Operator, configure metrics scraping with CRDs, and query cluster metrics.
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Uncloud: How to Deploy a Django Web Application
Learn how to quickly deploy your Python Django-based application to a remote Linux server under your control. This hands-on tutorial covers preparing and packaging a Django application from source code on your local machine and then deploying it to an Uncloud-managed machine, along with the networking ingress configuration and without using any external image registry.
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How Container Images Actually Work: Layers, Configs, Manifests, Indexes, and More
A practical deep dive into container image internals that will help you build a clear mental model of how images are composed, identified, stored, and distributed across registries.
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Transparent Ingress Proxy with eBPF and Envoy
This lab shows how to use eBPF to transparently redirect inbound traffic through an Envoy proxy on the server side, without modifying the application or client. You’ll learn how eBPF can intercept and restore connections so the service remains unaware of the proxy in the network path.
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Transparent Egress Proxy with eBPF and Envoy
This lab teaches you how to use eBPF to transparently intercept and redirect a client's outgoing traffic to an Envoy proxy without requiring any changes to the application code. You will build a system that recovers original connection metadata via socket-level hooks and uses SO_MARK to prevent infinite routing loops, replacing traditional, complex iptables rules with a high-performance eBPF alternative.
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All The Ways To Loop and Iterate in eBPF
In this tutorial you will learn different ways to implement loops in eBPF, explaining how iteration evolved from manual loop unrolling to modern mechanisms like bounded loops, helper functions, and open-coded iterators. It walks through the limitations, kernel version requirements, and practical examples for each approach so you can choose the most appropriate looping method for your eBPF programs.
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How Kubernetes Reinvented Virtual Machines - In a Good Sense
How Virtual Machines were used to deploy services. What old problems containers solve and what new problems create. How Kubernetes used containers to recreate Virtual Machines in a better way?
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Different Ways To Deliver Kernel Events from eBPF to User Space
In this tutorial, you’ll learn how eBPF applications send kernel events into user space using perf buffer and ring buffer, exploring their design, trade-offs, and performance implications. You’ll also learn how moderns solutions like Jibril handle high-throughput event delivery.
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Building an eBPF/XDP IP-in-IP Direct Server Return Load Balancer from Scratch
In this tutorial, you will learn how to build a IPIP DSR load balancer using eBPF/XDP, where backends from arbitrary networks send responses directly back to clients bypassing the load balancer.
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Kubernetes RCE: Exploiting nodes/proxy GET
Exploit a Kubernetes RBAC authorization bypass where nodes/proxy GET permissions allow command execution in any Pod.
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Building an eBPF/XDP L2 Direct Server Return Load Balancer from Scratch
In this tutorial, you will learn how to build an Layer 2 DSR load balancer using eBPF/XDP, where backends send responses directly back to clients bypassing the load balancer.
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Hands-On Introduction to Unikernels
Learn what a unikernel is and how it compares to a Linux container. Build and run your first unikernel inside a playground box.
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Building an eBPF/XDP NAT-Based Layer 4 Load Balancer from Scratch
Learn how an eBPF/XDP-based NAT Layer 4 load balancer works by building one from scratch. We implement simple connection tracking, deterministic hashing, and IP/MAC rewriting with a small, easy-to-follow example.
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Building an eBPF-based Firewall with LPM Trie–Based IP Range Matching
Learn how to build an eBPF/XDP firewall that filters packets by IP ranges using BPF_MAP_TYPE_LPM_TRIE and longest-prefix matching.
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Uncloud: How to Set Up a New Cluster
Learn how to create and manage a multi-machine Uncloud cluster from scratch. This hands-on tutorial walks you through initializing a cluster, adding machines, managing contexts, and deploying your first containerized service.
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Hands-On with XDP: eBPF for High-Performance Networking
In this tutorial, you’ll learn the fundamentals of eBPF and XDP through example code that parses packets across different protocol layers, demonstrates how XDP actions work, and shows how these building blocks form the foundation for high-performance networking applications.
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Network Traffic Rate Limiting with eBPF/XDP
Learn how to implement a basic per-client ICMPv6 packet rate limiter using eBPF/XDP. This tutorial shows how to track client activity with eBPF maps and enforce limits directly in the kernel—without any user-space interaction.
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How Container Filesystem Works: Building a Docker-like Container From Scratch
Learn how Linux containers are built from the ground up. Starting with the mount namespace and a root filesystem, see why PID, cgroup, UTS, and network namespaces naturally follow - and how this foundation makes concepts like bind mounts, volumes, and persistence in Docker or Kubernetes much easier to grasp.
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Why Does My eBPF Program Work on One Kernel but Fail on Another?
In this tutorial, we look at why eBPF programs can fail across kernel versions due to changes in structs, tracepoints, and function layouts. We look at examples of how these differences cause portability issues and how BPF CO-RE, BTF and vmlinux.h address them.
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Building Truly Portable eBPF Programs and BTFHub
In this tutorial, you’ll learn how to make your eBPF programs portable across kernels that lack built-in BTF support.
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eBPF Tracepoints, Kprobes, or Fprobes: Which One Should You Choose?
In this tutorial, we’ll look at how different eBPF tracing mechanisms work in practice by focusing on a single use case: capturing execve system call events. We’ll start with tracepoints, move on to raw tracepoints, and then cover kprobes and fprobes, showing how each attaches to the kernel and what data they expose. Along the way, we’ll compare their trade-offs in terms of stability, performance, and portability.
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eBPF Verifier: Why the Kernel Can Safely Run eBPF Programs
In this tutorial, you’ll learn why it is safe to run eBPF code in the kernel, some of its advantages compared to kernel modules, and why the verifier is the most crucial component of eBPF.
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Inspecting and Monitoring eBPF Applications
In this tutorial, you’ll learn how to inspect eBPF programs and maps loaded into the kernel with bpftool, gaining deeper visibility into how your eBPF application runs. We’ll also explore bpftop, a top-like interface that lets you monitor eBPF program activity in real time.
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Storing Data in eBPF: Your First eBPF Map
In this tutorial, you’ll learn how to store and update data inside the kernel, turning a simple eBPF Hello World program into one that tracks useful state. We’ll also briefly learn a few basics of bpftool, a handy CLI tool that will allow us to list and inspect our eBPF map.
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From Zero to Your First eBPF Program
In this first tutorial, you’ll run a pre-coded eBPF program and see it in action without writing any code yourself. We’ll walk through the important parts of the program so you understand how eBPF hooks and runs in the kernel. The goal is to get familiar with the workflow and core concepts before you start writing your own eBPF programs.
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Kubernetes: Runtime Class
Learn how to configure and use Kubernetes Runtime Classes to specify different container runtimes for your workloads. Explore different OCI runtimes and their scheduling constraints.
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Docker Run, Attach, and Exec: How They Work Under the Hood (and Why It Matters)
Dive into the internals of the Docker run, attach, and exec commands by following this highly visual and hands-on tutorial.
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Papercompanion for APL Center of Geospace Storms
OpenScience Demo content: How to capture a massive piece of high-performance compute (HPC) code named Kaiju and Gamera in a Container
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Kubernetes: Admission Control
Dive deep into Kubernetes admission control with hands-on examples. Learn how admission controllers influence cluster behavior, apply default configurations, and enforce policies for consistency and compliance.
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Provisioning a Kubernetes Cluster with kubeadm
Learn how to set up a Kubernetes cluster from scratch using kubeadm.
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Auto Unseal OpenBao/Vault with the Transit Secrets Engine
Learn how to auto-unseal works by using OpenBao'/Vault's builtin mechanism.
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Getting Started with OpenBao/Vault
Learn how to get started with OpenBao/Vault by walking through the basics of initialization, unsealing, authentication, and secret management.
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An Introduction to Docker Security
by Rory McCune
In this tutorial, we'll dive into the world of Docker Security, look at the attack surface of a Docker installation and show some straightforward container breakouts
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Running Dagger Pipelines on GitHub Actions
Learn how to integrate Dagger into your existing CI pipelines on GitHub Actions.
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Testing and Releasing Helm Charts with Dagger
Learn how to test, package and release Helm charts using Dagger.
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Containers are processes
by Rory McCune
In this brief tutorial we'll explore the idea that Docker containers are just processes, from the perspective of the operating system. Based on this Securitylabs blog post https://securitylabs.datadoghq.com/articles/container-security-fundamentals-part-1/
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What's Inside Distroless Container Images: Taking a Closer Look
What are these distroless images, really? Why are they needed? What's the difference between a container image built from a distroless base and a container image built from scratch? Let's take a deeper look.
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KubeBlocks Tutorial 201 - Seamless Upgrades
by Bryce Yu
Learn how to run any database on Kubernetes with KubeBlocks!
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KubeBlocks Tutorial 301 - Backup & Restore
by Bryce Yu
Learn how to run any database on Kubernetes with KubeBlocks!
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KubeBlocks Tutorial 401 – Observability in Action
by Bryce Yu
Learn how to run any database on Kubernetes with KubeBlocks!
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KubeBlocks Tutorial 501 – Auto-Tuning for Optimal Performance
by Bryce Yu
Learn how to run any database on Kubernetes with KubeBlocks!
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KubeBlocks Tutorial 101 - Getting Started
by Bryce Yu
Learn how to run any database on Kubernetes with KubeBlocks!
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Building Container Images FROM Scratch: 6 Pitfalls That Are Often Overlooked
While "FROM scratch" containers may seem functional, they often lack essential components that programs expect to find in their execution environment. Discover the most common pitfalls of building container images "FROM scratch" and learn how to avoid them.
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How to Build Smaller Container Images: Docker Multi-Stage Builds
Learn how to build smaller, more secure Docker container images using Multi-Stage Builds. This guide explains common sources of image bloat, best practices for slimming down production images, and practical examples for Node.js, Go, Rust, and other application stacks. Start optimizing your containers today!
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A Deeper Look into Node.js Docker Images: Help, My Node Image Has Python!
Choosing the right base image for your Node.js application can drastically affect its security, size, and performance. This post breaks down popular options - from slim and distroless to full-sized images - helping you navigate the trade-offs and pick the best fit for your development, build, and production needs.
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Controlling Process Resources with Linux Control Groups
Learn how to limit process resources using Linux cgroups - from the most basic and labour-intensive cgroupfs manipulation to the handiest systemd-run command.
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Docker Container Commands Explained: Understand, Don't Memorize
When you are new to Docker, the number of commands to study might be truly overwhelming. This tutorial shows a way to internalize the most important Docker commands without the brute-force memorization.
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How To Extract Container Image Filesystem Using Docker
How to explore the filesystem of a container image using nothing but the standard Docker means (and without running any containers).
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How Container Networking Works: Building a Bridge Network From Scratch
Begin with the basics to understand Docker and Kubernetes networking: learn how to create and interconnect Linux network namespaces using only command-line tools.
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Exploring Tetragon - A Security Observability Tool for Kubernetes, Docker, and Linux
What is Tetragon, how it works, and how to use it to detect and react to security-significant events in your Kubernetes, Docker, or plain Linux environment.
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Docker Containers vs. Kubernetes Pods - Taking a Deeper Look
Can a Kubernetes Pod be created with plain Docker commands? Learn the difference between Containers and Pods by exploring how they are implemented under the hood.
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Making Sense Out of Native Sidecar Containers in Kubernetes
Understand the "native" sidecar containers, learn their difference from regular and init containers and discover their advantages in this focused and highly practical tutorial.
