Alex Xu’s Post

What is k8s (Kubernetes)? . . k8s is a container orchestration system. It is used for container deployment and management. Its design is greatly impacted by Google’s internal system Borg. A k8s cluster consists of a set of worker machines, called nodes, that run containerized applications. Every cluster has at least one worker node. The worker node(s) host the Pods that are the components of the application workload. The control plane manages the worker nodes and the Pods in the cluster. In production environments, the control plane usually runs across multiple computers and a cluster usually runs multiple nodes, providing fault-tolerance and high availability. 🔹 Control Plane Components 1. API Server The API server talks to all the components in the k8s cluster. All the operations on pods are executed by talking to the API server. 2. Scheduler The scheduler watches the workloads on pods and assigns loads on newly created pods. 3. Controller Manager The controller manager runs the controllers, including Node Controller, Job Controller, EndpointSlice Controller, and ServiceAccount Controller. 4. etcd etcd is a key-value store used as Kubernetes' backing store for all cluster data. 🔹 Nodes 1. Pods A pod is a group of containers and is the smallest unit that k8s administers. Pods have a single IP address applied to every container within the pod. 2. Kubelet An agent that runs on each node in the cluster. It ensures containers are running in a Pod. 3. Kube Proxy kube-proxy is a network proxy that runs on each node in your cluster. It routes traffic coming into a node from the service. It forwards requests for work to the correct containers. – Subscribe to our weekly newsletter to get a Free System Design PDF (158 pages): https://bit.ly/3KCnWXq #systemdesign #coding #interviewtips .

What do version numbers mean? . . Semantic Versioning (SemVer) is a versioning scheme for software that aims to convey meaning about the underlying changes in a release. 🔹 SemVer uses a three-part version number: MAJOR.MINOR.PATCH. - MAJOR version: Incremented when there are incompatible API changes. - MINOR version: Incremented when functionality is added in a backward-compatible manner. - PATCH version: Incremented when backward-compatible bug fixes are made. 🔹 Example Workflow 1 - Initial Development Phase Start with version 0.1.0. 2 - First Stable Release Reach a stable release: 1.0.0. 3 - Subsequent Changes Patch Release: A bug fix is needed for 1.0.0. Update to 1.0.1. Minor Release: A new, backward-compatible feature is added to 1.0.3. Update to 1.1.0. Major Release: A significant change that is not backward-compatible is introduced in 1.2.2. Update to 2.0.0. 4 - Special Versions and Pre-releases Pre-release Versions: 1.0.0-alpha, 1.0.0-beta, 1.0.0-rc.1. Build Metadata: 1.0.0+20130313144700. – Subscribe to our weekly newsletter to get a Free System Design PDF (158 pages): https://bit.ly/3KCnWXq #systemdesign #coding #interviewtips .

Cybersecurity 101 in one picture. . . 1. Introduction to Cybersecurity 2. The CIA Triad 3. Common Cybersecurity Threats 4. Basic Defense Mechanisms To combat these threats, several basic defense mechanisms are employed: - Firewalls: Network security devices that monitor and control incoming and outgoing network traffic. - Antivirus Software: Programs designed to detect and remove malware. - Encryption: The process of converting information into a code to prevent unauthorized access. 5. Cybersecurity Frameworks –  Subscribe to our weekly newsletter to get a Free System Design PDF (158 pages): https://bit.ly/3KCnWXq    #systemdesign #coding #interviewtips  .

FREE Big Archive for System Design - 2023 Edition (PDF) is available now The PDF contains 𝐚𝐥𝐥 𝐦𝐲 𝐭𝐞𝐜𝐡𝐧𝐢𝐜𝐚𝐥 𝐩𝐨𝐬𝐭𝐬 published in 2023.    What’s included in the PDF?   🔹 Netflix's Tech Stack   🔹 Top 5 common ways to improve API performance   🔹 Linux boot Process Explained   🔹 CAP, BASE, SOLID, KISS, What do these acronyms mean?   🔹 Explaining JSON Web Token (JWT) to a 10 year old Kid   🔹 Explaining 8 Popular Network Protocols in 1 Diagram   🔹 Top 5 Software Architectural Patterns   🔹 𝐀𝐧𝐝 100+ 𝐦𝐨𝐫𝐞    Subscribe to our newsletter to receive the PDF download link: https://lnkd.in/eX-CfqCY #systemdesign #coding #interviewtips  .

Git Merge vs. Rebase vs. Squash Commit!  .  .  What are the differences?    When we 𝐦𝐞𝐫𝐠𝐞 𝐜𝐡𝐚𝐧𝐠𝐞𝐬 from one Git branch to another, we can use ‘git merge’ or ‘git rebase’. The diagram below shows how the two commands work.    𝐆𝐢𝐭 𝐌𝐞𝐫𝐠𝐞  This creates a new commit G’ in the main branch. G’ ties the histories of both main and feature branches.    Git merge is 𝐧𝐨𝐧-𝐝𝐞𝐬𝐭𝐫𝐮𝐜𝐭𝐢𝐯𝐞. Neither the main nor the feature branch is changed.    𝐆𝐢𝐭 𝐑𝐞𝐛𝐚𝐬𝐞  Git rebase moves the feature branch histories to the head of the main branch. It creates new commits E’, F’, and G’ for each commit in the feature branch.    The benefit of rebase is that it has 𝐥𝐢𝐧𝐞𝐚𝐫 𝐜𝐨𝐦𝐦𝐢𝐭 𝐡𝐢𝐬𝐭𝐨𝐫𝐲.    Rebase can be dangerous if “the golden rule of git rebase” is not followed.    𝐓𝐡𝐞 𝐆𝐨𝐥𝐝𝐞𝐧 𝐑𝐮𝐥𝐞 𝐨𝐟 𝐆𝐢𝐭 𝐑𝐞𝐛𝐚𝐬𝐞  Never use it on public branches! –  Subscribe to our weekly newsletter to get a Free System Design PDF (158 pages): https://bit.ly/3KCnWXq    #systemdesign #coding #interviewtips  .

HTTPS, SSL Handshake, and Data Encryption Explained to Kids.    HTTPS: Safeguards your data from eavesdroppers and breaches. Understand how encryption and digital certificates create an impregnable shield.    SSL Handshake: Behind the Scenes — Witness the cryptographic protocols that establish a secure connection. Experience the intricate exchange of keys and negotiation.    Secure Data Transmission: Navigating the Tunnel — Journey through the encrypted tunnel forged by HTTPS. Learn how your information travels while shielded from cyber threats.    HTML's Role: Peek into HTML's role in structuring the web. Uncover how hyperlinks and content come together seamlessly. And why is it called HYPER TEXT.    Over to you: In this ever-evolving digital landscape, what emerging technologies do you foresee shaping the future of cybersecurity or the web? –  Subscribe to our weekly newsletter to get a Free System Design PDF (158 pages): https://bit.ly/3KCnWXq    #systemdesign #coding #interviewtips  .

How to store passwords safely in the database and how to validate a password? Let’s take a look.   𝐓𝐡𝐢𝐧𝐠𝐬 𝐍𝐎𝐓 𝐭𝐨 𝐝𝐨 🔹 Storing passwords in plain text is not a good idea because anyone with internal access can see them.   🔹 Storing password hashes directly is not sufficient because it is pruned to precomputation attacks, such as rainbow tables.    🔹 To mitigate precomputation attacks, we salt the passwords.    𝐖𝐡𝐚𝐭 𝐢𝐬 𝐬𝐚𝐥𝐭? According to OWASP guidelines, “a salt is a unique, randomly generated string that is added to each password as part of the hashing process”.   𝐇𝐨𝐰 𝐭𝐨 𝐬𝐭𝐨𝐫𝐞 𝐚 𝐩𝐚𝐬𝐬𝐰𝐨𝐫𝐝 𝐚𝐧𝐝 𝐬𝐚𝐥𝐭? 1️⃣ A salt is not meant to be secret and it can be stored in plain text in the database. It is used to ensure the hash result is unique to each password.   2️⃣ The password can be stored in the database using the following format: 𝘩𝘢𝘴𝘩( 𝘱𝘢𝘴𝘴𝘸𝘰𝘳𝘥 + 𝘴𝘢𝘭𝘵).   𝐇𝐨𝐰 𝐭𝐨 𝐯𝐚𝐥𝐢𝐝𝐚𝐭𝐞 𝐚 𝐩𝐚𝐬𝐬𝐰𝐨𝐫𝐝? To validate a password, it can go through the following process: 1️⃣ A client enters the password. 2️⃣ The system fetches the corresponding salt from the database. 3️⃣ The system appends the salt to the password and hashes it. Let’s call the hashed value H1. 4️⃣ The system compares H1 and H2, where H2 is the hash stored in the database. If they are the same, the password is valid.    Over to you: what other mechanisms can we use to ensure password safety? –  Subscribe to our weekly newsletter to get a Free System Design PDF (158 pages): https://bit.ly/3KCnWXq    #systemdesign #coding #interviewtips  .

The Big Archive for System Design - 2023 Edition (PDF) is available now. And it's completely FREE. The PDF contains 𝐚𝐥𝐥 𝐦𝐲 𝐭𝐞𝐜𝐡𝐧𝐢𝐜𝐚𝐥 𝐩𝐨𝐬𝐭𝐬 published in 2023. What’s included in the PDF? 🔹 Netflix's Tech Stack 🔹 Top 5 common ways to improve API performance 🔹 Linux boot Process Explained 🔹 CAP, BASE, SOLID, KISS, What do these acronyms mean? 🔹 Explaining JSON Web Token (JWT) to a 10 year old Kid 🔹 Explaining 8 Popular Network Protocols in 1 Diagram 🔹 Top 5 Software Architectural Patterns 🔹 OAuth 2.0 Flows 🔹 What does API gateway do? 🔹 Linux file system explained 🔹 18 Key Design Patterns Every Developer Should Know 🔹 Best ways to test system functionality 🔹 Top 6 Load Balancing Algorithms 🔹 Top 12 Tips for API Security 🔹 𝐀𝐧𝐝 100+ 𝐦𝐨𝐫𝐞 Like, follow and subscribe to our newsletter to receive the PDF download link: https://bit.ly/3KCnWXq #systemdesign #coding #interviewtips .