Lab01: Daniil Mayorov (CBS-01)

app_go/README.md

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+# Lab01 — DevOps Info Service
+
+## Overview
+
+**DevOps Info Service (Go version)** is a lightweight web application written in Go that provides detailed information about the service itself, the system it runs on, and its runtime environment.
+
+This implementation is part of the **bonus task** for Lab 01 and is intended to demonstrate the advantages of using a compiled language in DevOps workflows, especially for containerization and multi-stage Docker builds.
+
+**Features:**
+
+* `GET /` — returns service, system, runtime, and request information
+* `GET /health` — simple health check endpoint
+* Configurable via environment variables
+
+---
+
+## Prerequisites
+
+* Go **1.24.5**
+
+---
+
+## Installation
+
+1. Clone the repository:
+
+```bash
+git clone https://github.com/Daniil20xx/DevOps-Core-Course.git
+```
+
+2. Navigate to the Go application directory:
+
+```bash
+cd app_go
+```
+
+3. Initialize Go module (if not already initialized):
+
+```bash
+go mod init devops-info-service
+```
+
+---
+
+## Running the Application
+
+### Run directly
+
+```bash
+cd app_go
+go run main.go
+```
+
+By default, the service runs on:
+
+```
+http://0.0.0.0:5000
+```
+
+### Run with custom configuration
+
+```bash
+HOST=127.0.0.1 PORT=8080 go run main.go
+```
+
+---
+
+## API Endpoints
+
+### `GET /`
+
+Returns detailed information about the service and the system.
+
+**Example:**
+
+```json
+{
+  "endpoints": [
+    {
+      "description": "Service information",
+      "method": "GET",
+      "path": "/"
+    },
+    {
+      "description": "Health check",
+      "method": "GET",
+      "path": "/health"
+    }
+  ],
+  "request": {
+    "client_ip": "::1",
+    "method": "GET",
+    "path": "/",
+    "user_agent": "Mozilla/5.0 (Windows NT; Windows NT 10.0; ru-RU) WindowsPowerShell/5.1.26100.7462"
+  },
+  "runtime": {
+    "current_time": "2026-01-28T08:32:20Z",
+    "timezone": "UTC",
+    "uptime_human": "0 hours, 24 minutes",
+    "uptime_seconds": 1452
+  },
+  "service": {
+    "description": "DevOps course info service",
+    "framework": "net/http",
+    "name": "devops-info-service",
+    "version": "1.0.0"
+  },
+  "system": {
+    "architecture": "amd64",
+    "cpu_count": 16,
+    "go_version": "go1.24.5",
+    "hostname": "Daniil",
+    "platform": "windows",
+    "platform_version": "go1.24.5"
+  }
+}
+```
+
+---
+
+### `GET /health`
+
+Returns service health status.
+
+**Example:**
+
+```bash
+curl http://localhost:8080/health
+```
+
+**Response:**
+
+```json
+{
+  "status": "healthy",
+  "timestamp": "2026-01-28T08:33:26Z",
+  "uptime_seconds": 1518
+}
+```
+
+---
+
+## Configuration
+
+The application can be configured using environment variables:
+
+| Environment Variable | Default   | Description                        |
+| -------------------- | --------- | ---------------------------------- |
+| `HOST`               | `0.0.0.0` | Host address to bind the server    |
+| `PORT`               | `8080`    | Port to run the application on     |
+
+---
+
+## Project Structure
+
+```
+app_go/
+├── main.go
+├── go.mod
+├── README.md
+└── docs/
+    ├── LAB01.md
+    └── screenshots/
+```

app_go/docs/GO.md

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+# GO — Language Selection Justification
+
+## Overview
+
+For the bonus part of Lab 01, the DevOps Info Service was reimplemented using **Go**, a compiled programming language widely used in modern DevOps.
+The goal of this implementation is to demonstrate the advantages of compiled languages in terms of performance, deployment, and containerization.
+
+---
+
+## Why Go?
+
+Go was selected for the following reasons:
+
+### 1. Compiled Language
+
+Go compiles source code into a **single native binary**, which eliminates the need for a runtime interpreter (unlike Python).
+This results in:
+
+* Faster application startup
+* Lower runtime overhead
+* Simpler deployment process
+
+---
+
+### 2. Standard Library for Web Services
+
+Go provides a powerful and production-ready HTTP server through the standard `net/http` package.
+This allows building web services without relying on external frameworks, reducing dependencies and potential security risks.
+
+---
+
+### 3. Performance and Resource Efficiency
+
+Compared to interpreted languages, Go applications:
+
+* Use less memory
+* Handle concurrent requests efficiently
+* Scale well under load
+
+This makes Go a popular choice for infrastructure tools, monitoring systems, and backend services.
+
+---
+
+## Comparison with Python Implementation
+
+| Aspect                | Python (Flask)          | Go                      |
+| --------------------- | ----------------------- | ----------------------- |
+| Language Type         | Interpreted             | Compiled                |
+| Startup Time          | Slower                  | Faster                  |
+| Deployment            | Requires Python runtime | Single binary           |
+| Docker Image Size     | Larger                  | Smaller                 |
+| Performance           | Good for small services | High                    |
+| Dependency Management | External packages       | Mostly standard library |
+
+---
+
+## Conclusion
+
+Go was chosen for the bonus implementation because it provides a clean, efficient, and production-ready approach to building web services.
+Using Go alongside Python in this lab demonstrates the trade-offs between interpreted and compiled languages and prepares the project for future DevOps tasks such as containerization, CI/CD pipelines, and Kubernetes deployments.

app_go/docs/LAB01.md

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+# LAB01 — DevOps Info Service (Go Version)
+
+## 1. Framework / Language Selection
+
+**Chosen Language:** Go (Golang) 1.24.5
+
+**Justification:**
+Go is a compiled language suitable for building lightweight, high-performance web services.
+
+---
+
+## 2. Best Practices Applied
+
+**1. Clean Code Structure**
+
+* Separation of concerns: utility functions, handlers, and main server logic
+* `getUptime()` function calculates runtime
+* Route handlers: `mainHandler` for `/`, `healthHandler` for `/health`
+* Consistent logging of requests
+
+**2. Error Handling**
+
+* Returns default page `/` if error happens
+
+**3. Logging**
+
+* Uses Go’s standard `log` package
+* Optional verbose logging via `DEBUG` environment variable
+
+**4. Environment Configuration**
+
+* `HOST`, `PORT`, `DEBUG` are configurable through environment variables
+
+**5. Dependency Management**
+
+* Uses Go modules (`go.mod`) to track dependencies
+
+---
+
+## 3. API Documentation
+
+### `GET /`
+
+Returns service, system, runtime, and request information.
+
+**Example Request:**
+
+```bash
+curl http://localhost:8080/
+```
+
+**Sample Response:**
+
+```json
+{
+  "endpoints": [
+    {
+      "description": "Service information",
+      "method": "GET",
+      "path": "/"
+    },
+    {
+      "description": "Health check",
+      "method": "GET",
+      "path": "/health"
+    }
+  ],
+  "request": {
+    "client_ip": "::1",
+    "method": "GET",
+    "path": "/",
+    "user_agent": "Mozilla/5.0 (Windows NT; Windows NT 10.0; ru-RU) WindowsPowerShell/5.1.26100.7462"
+  },
+  "runtime": {
+    "current_time": "2026-01-28T08:32:20Z",
+    "timezone": "UTC",
+    "uptime_human": "0 hours, 24 minutes",
+    "uptime_seconds": 1452
+  },
+  "service": {
+    "description": "DevOps course info service",
+    "framework": "net/http",
+    "name": "devops-info-service",
+    "version": "1.0.0"
+  },
+  "system": {
+    "architecture": "amd64",
+    "cpu_count": 16,
+    "go_version": "go1.24.5",
+    "hostname": "Daniil",
+    "platform": "windows",
+    "platform_version": "go1.24.5"
+  }
+}
+```
+
+---
+
+### `GET /health`
+
+Returns health status.
+
+**Example Request:**
+
+```bash
+curl http://localhost:8080/health
+```
+
+**Sample Response:**
+
+```json
+{
+  "status": "healthy",
+  "timestamp": "2026-01-28T08:33:26Z",
+  "uptime_seconds": 1518
+}
+```
+
+---
+
+## 4. Testing Evidence
+
+* **Main Endpoint:**
+  ![Main endpoint](screenshots/01-main-endpoint.png)
+
+* **Health Check:**
+  ![Health endpoint](screenshots/02-health-check.png)
+
+* **Command-line Test Example:**
+
+```bash
+curl http://localhost:8080/
+curl http://localhost:8080/health
+```
+
+---
+
+## 6. Summary
+
+The Go implementation mirrors the Python (Flask) version of the DevOps Info Service:
+
+* Same endpoints and JSON structure
+* Faster startup and compiled binary

app_go/go.mod

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+module app_go
+
+go 1.24.5