Contents

Docker

How to Run a Command on a Docker Image Stored in AWS ECR

• 💚 How to Run a Command on a Docker Image Stored in AWS ECR
  • 💛 Authenticate Docker with ECR
    • 🤍 Example
  • 💛 Pull the Image From ECR
  • 💛 Run the Image With a Command
  • 💛 Start an Interactive Shell

What is Docker Mount

• 💚 What Is Docker Mount?
  • 💛 Basic Syntax
  • 💛 Example
    • 🤍 What It Means:
  • 💛 Why Use This?
  • 💛 Other Mount Use Cases
  • 💛 Reference

How to Check Environment Variables in a Docker Container

• 💚 How to Check Environment Variables in a Docker Container
  • 💛 1. While Running a Container
    • 🤍 Option A: Use ‘docker exec’
    • 🤍 Option B: Use a Shell
• or
• or
  • 💛 2. When Creating a Container
  • 💛 3. From ‘docker inspect’
  • 💛 References

OCI and Registries

• 💚 OCI (Open Container Images) and Registries
  • 💛 What is OCI?
  • 💛 OCI Images
  • 💛 OCI Registries
  • 💛 Helm + OCI
    • 🤍 Why Use OCI for Helm Charts?
  • 💛 References

How to Sign in Docker with AWS SSO

• 💚 Command
• 💚 Explain
  • 💛 Sign in Docker with Terminal
  • 💛 Sign in Docker by AWS Profile
• 💚 Reference

GitHubActions

How to Configure GitHub on Your Terminal

• 💚 How to Configure Git on Your Terminal
  • 💛 1. Set Your Identity (Required)
  • 💛 2. Check Your Config
  • 💛 3. Set Credential Helper (avoid typing password/PAT every time)
    • 🤍 macOS
    • 🤍 Linux (simple store)
  • 💛 4. Set Editor (Optional)
    • 🤍 Vim
  • 💛 5. Enable Colored Output (Pretty UI)
  • 💛 7. Setup SSH Instead of Password
• Hi eeeemune! You've successfully authenticated, but GitHub does not provide shell access.
  • 💛 Example Full Setup (Quick Copy)
  • 💛 References

How to set a team as Auto-Assigned Reviewers

• 💚 How to set a team as Auto-Assigned Reviewers
  • 💛 Make Sure You Have a GitHub Team
  • 💛 Create or Edit a File
• All files will be reviewed by the backend team
• All files in the frontend folder will be reviewed by the frontend team - 💛 Enable CODEOWNERS Auto-Assignment in Settings - 💛 Things to Note

How to Pull a Specific Branch from a Remote Git Repository

• 💚 How to Pull a Specific Branch from a Remote Git Repository
  • 💛 1. Check Remote Branches
  • 💛 2. Pull a Specific Branch (first time)
  • 💛 3. Pull Updates (branch already exists locally)
  • 💛 Bonus: Just Download Without Switching
  • 💛 References

How to Use git diff Command

• 💚 How to Use git diff Command
  • 💛 What does it do?
  • 💛 Common Usages
    • 🤍 Show unstaged changes (what you've edited but not added)
    • 🤍 Show staged changes (what you've added with )
    • 🤍 Show everything (staged + unstaged)
  • 💛 Compare Between Branches
  • 💛 Compare Between Commits
  • 💛 See Only File Names (not full diff)
  • 💛 Compare with Remote Branch
  • 💛 References

GitHub Action Runner

• 💚 What is the ‘runner’?
  • 💛 GitHub Actions Runner
  • 💛 Where does the runner live?
  • 💛 Example

Kubernetes

What is Karpenter

• 💚 What is Karpenter?
  • 💛 Karpenter
  • 💛 Why Do We Need It?
  • 💛 How It Works
    • 🤍 Flow
  • 💛 What Makes Karpenter Special?
    • 🤍 Traditional Cluster Autoscaler
    • 🤍 Karpenter
  • 💛 Simple Config Example
  • 💛 References

Helm Chart and Release

• 💚 Helm Chart and Release
  • 💛 What is a Helm Release?
  • 💛 Example
  • 💛 In Terraform

ECS to EKS Migration Guide

• 💚 ECS to EKS Migration Guide
  • 💛 Before You Start…
    • 🤍 Essential Concept
    • 🤍 The Big Picture
    • 🤍 Overal Structure
  • 💛 IAM Setup
    • 🤍 Why Do We Need IAM Roles?
    • 🤍 Cluster Role
• iam.tf
• Create the role
• Attach the required policy - 🤍 Node Role
• Create the role
• Nodes need THREE policies: - 🤍 User Access
• Import your IAM user
• Add yourself to the cluster's access list
• Give yourself admin permissions
  • 💛 Creating the EKS Cluster
    • 🤍 The Cluster Itself
• cluster.tf - 🤍 Node Groups - 🤍 Essential Add-ons
• DNS for service discovery (pods find each other by name - like a dns server in K8s)
• Networking (assigns IPs to pods)
• Network routing
• Metrics (needed for auto-scaling)
  • 💛 Networking & Security Groups
    • 🤍 Why This Matters?
    • 🤍 EKS → RDS
    • 🤍 EKS → Redis(ElastiCache)
    • 🤍 ALB → EKS Pods
• First, create a security group for the ALB
• Then allow ALB to reach EKS nodes
  • 💛 Load Balancer
    • 🤍 Create the ALB
    • 🤍 Create HTTPS Listener
    • 🤍 Create Target Groups
    • 🤍 Create Listener Rules
    • 🤍 Connect ALB to EKS (TargetGroupBinding)
  • 💛 Managing Secrets
    • 🤍 Background - The Problem
    • 🤍 Variable Flows
    • 🤍 Fetch Secrets from SSM by Terraform
• Get all parameters under /chartmetric/shared/
• Get environment-specific parameters - 🤍 Create Kubernetes Secrets - 🤍 Use Secrets in Deployments
• In your deployment spec:
• This value will WIN over anything in api-secrets
• This loads from secrets (but env above takes precedence)
  • 💛 Deploying Applications
    • 🤍 Basic Deployment
    • 🤍 Creating a Service
    • 🤍 Horizontal Pod Autoscaler (HPA)
  • 💛 Redis Configuration
    • 🤍 The Setup
    • 🤍 Define Redis in Environment Config
• environments.tf - 🤍 Create Redis Clusters
• redis.tf - 🤍 Connect Pods with Redis
• In deployment spec:
  • 💛 DNS & Traffic Migration
    • 🤍 How Can We Migrate with Zero-Downtime?
    • 🤍 Create DNS Records
    • 🤍 Update CloudFront
    • 🤍 Attach WAF

How to Use Secrets in Kubernetes

• 💚 How to Use Secrets in Kubernetes
  • 💛 Create a Secret
  • 💛 Check The Secret
    • 🤍 List Up Secrets
    • 🤍 See The Value for Secret
  • 💛 References

1. Kubernetes Clusters

• 💚 Objectives
• 💚 Control Plane
• 💚 Kubelet
  • 💛 Node-level Component
• 💚 Reference

3. Kubernetes Services

• 💚 Kubernetes Services
  • 💛 What is a Service?
  • 💛 Why Use a Service?
  • 💛 Types of Services
    • 🤍 ClusterIP
    • 🤍 NodePort
    • 🤍 LoadBalancer
    • 🤍 ExternalName
  • 💛 How Do Services Know Where to Send Traffic?
    • 🤍 Example: Service with Selector
  • 💛 What if There's No Selector?
  • 🤍 Summary
• Reference

2. Deploy an App

• 💚 Reference
• 💚 Objectives
• 💚 Deployments
  • 💛 What is a Deployment?
  • 💛 Why is it Useful?
  • 💛 What Happens If a Pod Dies?
    • 🤍 Real-Life Example
  • 💛 Summary

What is The Kubernetes

• 💚 Background
  • 💛 Monoliths
    • 🤍 Disadvantages of Monoliths
  • 💛 Microservices
    • 🤍 How to Run Microservices
• 💚 Kubernetes
  • 💛 What is the Kubernetes?
  • 💛 Key Goals
    • 🤍 Maximize Capacity
    • 🤍 Adapt to Demand
    • 🤍 Don’t Go Dark
    • 🤍 Abstraction
  • 💛 Notations
    • 🤍 Pod and Container
    • 🤍 Node and Cluster
  • 💛 Abstracted Infrastructure of Kubernetes
    • 🤍 Why Abstracted Infra is Needed?
    • 🤍 Immutable Template
    • 🤍 Benefits
  • 💛 Self-Healing in Kubernetes
    • 🤍 Ideal State vs Actual State
    • 🤍 Update Mechanisms
    • 🤍 Labels
    • 🤍 Services
• 💚 References

What is K3s

What is Helm

• 💚 What is Helm?
  • 💛 Short Answer
  • 💛 Why Use Helm?
  • 💛 What Is a Helm Chart?
    • 🤍 Example:
  • 💛 Helm Workflow
  • 🤍 Summary

Harbor

How to Check Harbor Connection

• 💚 How to Check Harbor Connection
  • 💛 Background
  • 💛 How to check
    • 🤍 Command
    • 🤍 Succeed
    • 🤍 Failure

What is Harbor

• 💚 Harbor
  • 💛 What is Harbor?
  • 💛 Key Features
    • 🤍 Stores container images & Helm charts (OCI format)
    • 🤍 Controls who can see or change things (RBAC)
    • 🤍 Scans for security issues
    • 🤍 Signs and verifies images (trust)
    • 🤍 Replicates to other registries
    • 🤍 Login with your company account (LDAP/AD)
    • 🤍 Has a website and API
  • 💛 How Harbor fits with Helm and OCI
  • 💛 Typical Use Cases
  • 💛 References

Others

Data Driven Design Pattern

• 💚 Data-Driven Design Pattern
  • 💛 What is Data-Driven Design Pattern?
  • 💛 Why Use It?
  • 💛 Example
    • 🤍 Traditional (Hard-coded)
    • 🤍 Data-Driven
  • 💛 Summary

How to Connect a Slack App

• 💚 How to Connect a Slack App
  • 💛 Create a Slack Incoming Webhook
  • 💛 Enable Socket Mode
  • 💛 Add a Coolify Webhook Trigger
    • 🤍 Configure a Webhook
    • 🤍 Set the Webhook to Your Application

How to Get HTTP Certificate

• 💚 How to Get HTTP Certificate
  • 💛 Install Nginx and Certbot
  • 💛 Configure Nginx as reverse proxy
• /etc/nginx/sites-available/mcp
  • 💛 Enable the site
  • 💛 Obtain SSL certificate
  • 💛 Enable auto-renual

How to Connect a Slack App

• 💚 How to Connect a Slack App

  • 💛 Create a Slack Incoming Webhook
  • 💛 Enable Socket Mode
  • 💛 Add a Coolify Webhook Trigger
    • 🤍 Configure a Webhook
    • 🤍 Set the Webhook to Your Application

• 💚 How to Connect a Slack App

• 💚 How to Connect a Slack App

  • 💛 Create a Slack Incoming Webhook

  • 💛 Enable Socket Mode

  • 💛 Add a Coolify Webhook Trigger

    • 🤍 Configure a Webhook
    • 🤍 Set the Webhook to Your Application

  • 💛 Create a Slack Incoming Webhook

  • 💛 Enable Socket Mode

  • 💛 Add a Coolify Webhook Trigger

    • 🤍 Configure a Webhook
    • 🤍 Set the Webhook to Your Application

How VPN Works

• 💚 How VPN Works?
  • 💛 What is a VPN?
  • 💛 Why use a VPN?
  • 💛 How VPN changes network behavior
    • 🤍 Networking Concepts Involved
  • 💛 Types of VPNs
  • 💛 What gets affected?
  • 💛 Common VPN Protocols
  • 💛 What does encrypted mean?
  • 💛 Common Use Cases
  • 💛 References

Network

How to Set Up VPN with Wireguard

• 💚 How to Set Up VPN with Wireguard
  • 💛 Install Wireguard
  • 💛 Generate keys on each machine
  • 💛 Set Up Server
• Client 1
• Client 2
  • 💛 Set Up Client

What is NAT

• 💚 What is NAT?
  • 💛 NAT = Network Address Translation
  • 💛 Why do we need NAT?
  • 💛 How does it work?
    • 🤍 Simple Example
  • 💛 Types of NAT
  • 💛 Where is NAT used?
  • 💛 References

Linux

Setting the Root Password for the First Time

• 💚 Setting the Root Password for the First Time
  • 💛 Step-by-Step

How to Get My IP on Linux

• 💚 How to Get My IP on Linux
  • 💛 Public
    • 🤍 IPv6
• 2603:3024:269:2200::bb22 - 🤍 IPv4
  • 💛 Private
• 10.1.10.198

How to Create a New User for SSH

• 💚 How to Create a New User for SSH
  • 💛 1. Add the User
  • 💛 2. Add User to Group (optional)
  • 💛 3. Create Folder
  • 💛 4. Add Public SSH Key
  • 💛 5. Test the Login
    • 🤍 Example
  • 💛 References

GCP

How to Create OAuth Client

• 💚 How to Create OAuth Client
  • 💛 Reference
  • 💛 Create OAuth Client
    • 🤍 Go to Google Auth Platform → Clients Tab
    • 🤍 Create Client
  • 💛 Save Auth Information
    • 🤍 Download Auth JSON

Python

How to Use Poetry

• 💚 How to Use Poetry
  • 💛 What is Poetry?
  • 💛 Quick Start
    • 🤍 1. Install Poetry
    • 🤍 2. Create a New Project
    • 🤍 3. Add Dependencies
    • 🤍 4. Install Everything (existing project)
    • 🤍 5. Run Commands Inside Environment
    • 🤍 6. Update Dependencies
    • 🤍 7. Check Dependency Graph
    • 🤍 8. Publish Your Package
  • 💛 Useful Extras
  • 💛 Workflow Example

How to Use requirements in Python

• 💚 How to Use requirements.txt in Python
  • 💛 What is requirements.txt?
  • 💛 Install Packages from requirements.txt
  • 💛 Create Your Own requirements.txt
  • 💛 4. Use with Virtual Environments
  • 💛 Best Practices
• Web framework
  • 💛 References

DNS

What does 'Your connection is not private' mean

• 💚 What Does Your Connection is Not Private Mean?
  • 💛 What Is SSL?
  • 💛 Why This Error Happens
    • 🤍 1. Expired or invalid SSL certificate
    • 🤍 2. Your computer’s date/time is wrong
    • 🤍 3. Man-in-the-middle (MITM) attack
    • 🤍 4. Untrusted certificate authority (CA)
  • 💛 What You See
  • 💛 Developer Tips
  • 💛 References

Terraform

Add a New GitHub Member with Terraform

• 💚 Add a New GitHub Member with Terraform
  • 💛 Go to the Files
• teams.terraform → defines GitHub teams
• membership.terraform → defines who’s in each team
  • 💛 Add a New Member
• membership.tf
  • 💛 Apply Terraform
  • 💛 Commit the Change & Create a PR

TroubleShootings

docker-entrypoint.sh: exec format error

Terraform Tutorial

• 💚 Terraform Tutorial
  • 💛 What is Terraform?
    • 🤍 Example
  • 💛 Terraform Workflow
  • 💛 Core Concepts
  • 💛 Variables & Outputs
    • 🤍 variables.tf
    • 🤍 main.tf
    • 🤍 outputs.tf
  • 💛 State Management
  • 💛 Modules
    • 🤍 Example
  • 💛 Best Practices
  • 💛 References

AWS

How to connect your terminal to EKS

• 💚 How to connect your terminal to EKS
  • 💛 Prerequisites
    • 🤍 Required tools
  • 💛 Steps
    • 🤍 1. Verify AWS access
    • 🤍 2. Generate ‘kubeconfig’ for EKS
• Real example - 🤍 3. Select and check current context - 🤍 4. Test

Terrraform

Terraform Module

• 💚 Terraform Module
  • 💛 What is a Module?
  • 💛 Basic Structure
  • 💛 Example
    • 🤍 Configure the Module
• variables.tf (input)
• main.tf
• outputs.tf (output) - 🤍 Use the Module
  • 💛 Module Source Types
    • 🤍 Local Module
    • 🤍 GitHub Module
    • 🤍 Terraform Registry
  • 💛 Best Practices
  • 💛 References