Docker Basics for DevOps Engineers

Day 06 of #90DaysOfDevOps 🚀 Linux File I/O: A Core DevOps Skill Today I revisited the basics — this time thinking like an operator, not a student. Reading and writing files is part of daily DevOps work: → Tailing logs during an incident at 2 AM → Updating configs in deployments → Capturing script output for debugging → Managing YAML, Dockerfiles, and shell scripts What I practiced today: ✅ `echo "..." > file.txt` — overwrite with intention (one wrong `>` can wipe a config file) ✅ `echo "..." >> file.txt` — safe append for logs and configs ✅ `echo "..." | tee -a file.txt` — write AND display simultaneously ✅ `cat`, `head`, `tail` — inspect file contents at different granularities 💡 Command I'll use often: `tee` Perfect for scripts where output needs to be both visible and logged at the same time. 🔑 Key Insight: Every config, log, Dockerfile, and manifest is just text. Engineers who handle text efficiently troubleshoot faster and ship faster. #90DaysOfDevOps #DevOpsKaJosh #TrainWithShubham #Linux #DevOps

The First Step: Diving into Linux for DevOps! I am thrilled to share that I’ve officially taken my first step toward becoming a DevOps Engineer! 🚀 Understanding that Linux is the heartbeat of the cloud and automation, I’ve spent the last few weeks diving deep into its fundamentals. I want to give a huge shout-out to Technical Guftgu and Train with Shubham for their incredible content—your tutorials have made complex concepts so much easier to grasp! 🛠️ What I’ve been practicing: Beyond the basics, I’ve been getting comfortable with the CLI. Some of the essential commands I’ve mastered include: Navigation: pwd, ls, cd File Operations: mkdir, touch, cp, mv Viewing content: cat, less, head, tail Permissions: chmod, chown (Critical for security!) Data Processing: grep, awk, sed,find Process Management: top, ps, kill and many more commands 🔗 Deep Dive: Hard Links vs. Soft Links One of the most interesting concepts I explored was File Linking. Understanding the difference is a game-changer for managing system files: Soft Link (Symbolic Link): It’s like a shortcut in Windows. It points to the file name. If the original file is deleted, the link breaks (dangling link). Hard Link: It points directly to the inode (the physical data on the disk). Even if you delete the original file, the data remains accessible through the hard link. This is just the beginning. Up next: Shell Scripting and Git! 💻 #DevOps #Linux #TechJourney #CloudEngineering #LearningInPublic #OpenSource #ContinuousLearning Technical Guftgu TrainWithShubham

🚀 Day 7 of My 14 Days Docker Journey | Real DevOps Project: Log Monitoring System 🔥 After learning Docker fundamentals (Images, Dockerfile, Volumes, Networking), I built my first real DevOps-style project 💪 🧠 💡 Project: Log Monitoring System (Docker) In real-world systems, applications generate logs continuously. So I built a mini system where: 👉 One container generates logs 👉 Another container monitors logs in real-time 🧩 Architecture App Container → Volume → Viewer Container ✔ Shared storage using Docker Volumes ✔ Real-time log streaming using tail -f ✔ Multi-container communication 🛠️ What I Used ✔ Dockerfile (custom images) ✔ Docker Volumes (data persistence) ✔ Docker Networking (container communication) ✔ Linux scripting 🔥 Key Learning 💥 Containers are temporary, but data can persist using volumes 💥 Real-world systems separate: Log generation Log monitoring ⚡ Challenges I Faced ❌ Container execution error (exec ./app.sh) ❌ File format issues (Linux vs Windows) ✔ Debugged using: docker logs docker exec Container inspection 👉 This was a huge learning moment 🔥 🎯 Outcome ✔ Built a working multi-container system ✔ Logs generated & streamed in real-time ✔ Strong understanding of Docker internals GitHub Repo Link : https://lnkd.in/gXp7sPR6 💬 If you're learning DevOps, let’s connect & grow together! #Docker #DevOps #LearningInPublic #CloudComputing #AWS #Linux #Containers #BuildInPublic #TechJourney

🚫 DevOps Beginners: Stop Rushing into Kubernetes! ☸️ In my previous posts, I’ve shared how I break (and fix) complex bare-metal Talos setups, but I see many engineers trying to run before they can walk. The most common mistake I see beginners making? Trying to master Kubernetes simultaneously with Linux and Containers. You cannot skip the foundation. If you want to break into DevOps and follow industry best practices (ensuring you are not just "making it work," as I always say), you need to gain that deep knowledge of the fundamentals first. This is the order I always recommend: 1️⃣ Learn Linux First. It is the core operating system. You cannot properly secure cluster components or network access if you don’t understand the kernel they sit on. 2️⃣ Master Docker and Containers. K8s orchestrates containers. You must understand how to build, run, and manage them practically. 🐋 3️⃣ Then Tackle K8s. ☸️ The Book Recommendation for Today 📖 To help you bridge that gap and master step #2 (Containers), I want to recommend an excellent intro. The Ultimate Docker Container Book by Gabriel N. Schenker. This book is a fantastic resource. What stands out to me is that it moves beyond basic tutorials and provides the practical blueprints needed to properly "Build, ship, deploy, and scale containerized applications". It teaches you how to design stable stateful applications (which are always the scary part of K8s). It gives you the "expert insight" mandatory for understanding how stateful workloads and persistent volumes behave before you add the complexity of Kubernetes orchestration. Take the time to master the fundamentals first. Your future production cluster-and your sanity will thank you! 🚀 Huge thanks to Packt for publishing such accessible guides for bridging the gap between theory and messy real-world implementation and Deepak Kumar for sending me the digital copy! 👇 Let’s help the beginners out as the market is not the best right now! #DevOps #Kubernetes #k8s #Docker #Containers #Linux #ContinuousLearning #onlydevops #Packt

Below, I am sharing some practical insights that I have experienced. If you're new to Docker Hardened Images or experiencing the same issue as me, the information below will assist you. Please refer to the link below to view the available Docker hardened images :- https://lnkd.in/gy-QATjv DHI is utilized in production due to its ultra-lightweight nature and its foundation on Alpine and Debian Linux. The lightweight nature means it doesn't contain sh, apt, curl, sudo, or wget. For further details, check out the link below. https://lnkd.in/gXZ3Whk5 The command to access the DHI container terminal differs from the usual one of 'docker exec -it <unk> container-name> /bin/bash', but it is not effective. 'docker exec -it 'container-name> /bin/sh' is the command used for DHI. To use DHI, it is necessary to log in to 'dhi.io' using your system or cloud terminal, and then execute Compose, build, or pull the DHI image. Take a look at the other sections of the post that is similar to this one 1. https://lnkd.in/gNUXSCs7 2. https://lnkd.in/gHTYzUZ4 #Docker #DevOps #Containerization #LearnDevOps #coding [ Docker, DevOps, Containerization, LearnDevOps, coding ]

Below, I am sharing some practical insights that I have experienced. If you're new to Docker Hardened Images or experiencing the same issue as me, the information below will assist you. Please refer to the link below to view the available Docker hardened images :- https://lnkd.in/gy-QATjv DHI is utilized in production due to its ultra-lightweight nature and its foundation on Alpine and Debian Linux. The lightweight nature means it doesn't contain sh, apt, curl, sudo, or wget. For further details, check out the link below. https://lnkd.in/gXZ3Whk5 The command to access the DHI container terminal differs from the usual one of 'docker exec -it <unk> container-name> /bin/bash', but it is not effective. 'docker exec -it 'container-name> /bin/sh' is the command used for DHI. To use DHI, it is necessary to log in to 'dhi.io' using your system or cloud terminal, and then execute Compose, build, or pull the DHI image. Take a look at the other sections of the post that is similar to this one 1. https://lnkd.in/gBX6cGyw 2. https://lnkd.in/gNUXSCs7 #Docker #DevOps #Containerization #LearnDevOps #coding [ Docker, DevOps, Containerization, LearnDevOps, coding ]

🚀 From Zero to 10 Running Containers – My DevOps Hands-on Journey 🔥 Today I built a complete end-to-end Docker setup from scratch and scaled it like a pro 💪 🔹 Installed Docker on Linux VM 🔹 Pulled Nginx image 🔹 Cloned project from GitHub 🔹 Deployed custom app inside container 🔹 Created custom Docker image (streamflix) 🔹 Configured Docker Network 🔹 Exposed application via ports 🔹 Scaled application to 10 containers 🚀 💡 Faced real-world issues & learned: ❌ Permission denied (Docker socket) ❌ Wrong command syntax (network, commit) ❌ Network not found issue ❌ Container name conflicts ✅ Fixed everything step by step like real DevOps engineer 🔥 Final Result: 👉 10 containers running on ports 8081–8090 👉 Fully working scalable setup This is what real learning looks like – Not just theory, but solving real errors 💯 📌 Key Learning: "Errors are not failures, they are DevOps tutorials in disguise." #DevOps #Docker #Linux #Cloud #Azure #Kubernetes #LearningByDoing #100DaysOfDevOps#devopsinsiders

You’ve seen the roadmap. You’ve learned the basics. You know what to do. But most people still won’t start. Why? Because they wait. “I’ll start next week.” “I need more time.” “I’m not ready yet.” And 6 months later… Nothing changes. Here’s the truth: 👉 You don’t need more content 👉 You don’t need more tutorials 👉 You need to start Every DevOps engineer you admire… Started before they felt ready. If you want to change your career: ✔ Start learning Linux ✔ Practice daily ✔ Build real skills Because waiting won’t change anything. Action will. Save this as a reminder. Follow me if you want real DevOps skills (not tutorial knowledge). #DevOps #Linux #CareerGrowth #CloudComputing #Motivation

If you haven't subscribed to EverythingDevOps as a DevOps Engineer, you're missing out. A newsletter just meant for you. I learned new Linux commands today I've never heard of. Did you know you can use a line of command to convert documents into different formats, instead of going through the website converters online? This is not a paid advertisment by the way. This is just me pointing you in the right direction. #EverythingDevOps #devops #IT #informationtechnology #software #tech #linkedin #linkedinvoices

🚨 𝗔 𝘀𝗶𝗻𝗴𝗹𝗲 𝘄𝗿𝗼𝗻𝗴 𝗽𝗲𝗿𝗺𝗶𝘀𝘀𝗶𝗼𝗻 𝗰𝗮𝗻 𝗯𝗿𝗲𝗮𝗸 𝗮𝗻 𝗲𝗻𝘁𝗶𝗿𝗲 𝗽𝗿𝗼𝗱𝘂𝗰𝘁𝗶𝗼𝗻 𝘀𝘆𝘀𝘁𝗲𝗺. Sounds dramatic… but it happens more often than you think. While learning Linux for DevOps, I discovered that many real-world issues are not caused by bugs in code — they’re caused by 𝗶𝗻𝗰𝗼𝗿𝗿𝗲𝗰𝘁 𝗳𝗶𝗹𝗲 𝗽𝗲𝗿𝗺𝗶𝘀𝘀𝗶𝗼𝗻𝘀. 💡 𝘋𝘢𝘺 11 𝘰𝘧 𝘮𝘺 𝘋𝘦𝘷𝘖𝘱𝘴 𝘑𝘰𝘶𝘳𝘯𝘦𝘺 Today I explored two very important Linux commands: 🔐 `𝘤𝘩𝘮𝘰𝘥` 👤 `𝘤𝘩𝘰𝘸𝘯` These commands control 𝘄𝗵𝗼 𝗰𝗮𝗻 𝗮𝗰𝗰𝗲𝘀𝘀, 𝗺𝗼𝗱𝗶𝗳𝘆, 𝗼𝗿 𝗲𝘅𝗲𝗰𝘂𝘁𝗲 𝗳𝗶𝗹𝗲𝘀 𝗼𝗻 𝗮 𝘀𝘆𝘀𝘁𝗲𝗺. And in DevOps, this matters a lot. --- 📖 Imagine this scenario: An application is deployed successfully. But when the service starts… ❌ It cannot read a configuration file ❌ It cannot access a log directory ❌ It fails to start The problem? Not the code. Not the server. 👉 Just 𝘄𝗿𝗼𝗻𝗴 𝗽𝗲𝗿𝗺𝗶𝘀𝘀𝗶𝗼𝗻𝘀. --- 🔹 `𝗰𝗵𝗺𝗼𝗱` — 𝗖𝗵𝗮𝗻𝗴𝗲 𝗙𝗶𝗹𝗲 𝗣𝗲𝗿𝗺𝗶𝘀𝘀𝗶𝗼𝗻𝘀 This command controls what users can do with a file. Example: ``` 𝘤𝘩𝘮𝘰𝘥 755 𝘴𝘤𝘳𝘪𝘱𝘵.𝘴𝘩 ``` This means: ✔ Owner can read, write, execute ✔ Others can read and execute DevOps engineers use this when: • Making deployment scripts executable • Securing configuration files • Controlling access to directories --- 🔹 `𝗰𝗵𝗼𝘄𝗻` — 𝗖𝗵𝗮𝗻𝗴𝗲 𝗙𝗶𝗹𝗲 𝗢𝘄𝗻𝗲𝗿𝘀𝗵𝗶𝗽 Sometimes the issue is not permission… it's ownership. Example: ``` 𝘤𝘩𝘰𝘸𝘯 𝘶𝘣𝘶𝘯𝘵𝘶:𝘶𝘣𝘶𝘯𝘵𝘶 𝘢𝘱𝘱.𝘭𝘰𝘨 ``` This assigns the file to a specific user and group. Very common when working with: ✔ Docker containers ✔ Application logs ✔ Server directories --- 🔥 One thing I learned today: Security in Linux is 𝗻𝗼𝘁 𝗼𝗻𝗹𝘆 𝗮𝗯𝗼𝘂𝘁 𝗳𝗶𝗿𝗲𝘄𝗮𝗹𝗹𝘀 𝗼𝗿 𝗮𝘂𝘁𝗵𝗲𝗻𝘁𝗶𝗰𝗮𝘁𝗶𝗼𝗻. It also starts with 𝗰𝗼𝗿𝗿𝗲𝗰𝘁 𝗳𝗶𝗹𝗲 𝗽𝗲𝗿𝗺𝗶𝘀𝘀𝗶𝗼𝗻𝘀. --- 📌 My biggest takeaway: In DevOps, small details like permissions can decide whether an application runs smoothly… or crashes immediately. And that’s why mastering Linux fundamentals is so important. --- 💬 Quick question for DevOps engineers here: Which permission do you use the most? `𝘤𝘩𝘮𝘰𝘥 755` `𝘤𝘩𝘮𝘰𝘥 777` or something else? Let’s discuss 👇 --- #DevOps #Linux #LinuxPermissions #CloudComputing #DevOpsEngineer #SRE #TechLearning #OpenSource #ITCar