Lab03 implementation

.github/workflows/go-ci.yml

@@ -0,0 +1,69 @@
+name: Go CI
+
+on:
+  push:
+    branches: [master, lab03]
+    paths:
+      - 'app_go/**'
+      - '.github/workflows/go-ci.yml'
+  pull_request:
+    branches: [master]
+    paths:
+      - 'app_go/**'
+      - '.github/workflows/go-ci.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    name: Lint & Test
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: app_go
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.21'
+          cache-dependency-path: app_go/go.mod
+
+      - name: Lint with golangci-lint
+        uses: golangci/golangci-lint-action@v6
+        with:
+          working-directory: app_go
+
+      - name: Run tests
+        run: go test -v ./...
+
+  docker:
+    name: Build & Push Docker
+    needs: test
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push'
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Generate CalVer tag
+        id: version
+        run: echo "TAG=$(date +%Y.%m).${{ github.run_number }}" >> "$GITHUB_OUTPUT"
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: app_go
+          push: true
+          tags: |
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-info-service-go:${{ steps.version.outputs.TAG }}
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-info-service-go:latest

.github/workflows/python-ci.yml

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+name: Python CI
+
+on:
+  push:
+    branches: [master, lab03]
+    paths:
+      - 'app_python/**'
+      - '.github/workflows/python-ci.yml'
+  pull_request:
+    branches: [master]
+    paths:
+      - 'app_python/**'
+      - '.github/workflows/python-ci.yml'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    name: Lint & Test
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: app_python
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+          cache: 'pip'
+          cache-dependency-path: app_python/requirements-dev.txt
+
+      - name: Install dependencies
+        run: pip install -r requirements-dev.txt
+
+      - name: Lint with ruff
+        run: ruff check .
+
+      - name: Run tests with coverage
+        run: pytest -v --cov=. --cov-report=xml --cov-report=term
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          file: app_python/coverage.xml
+          token: ${{ secrets.CODECOV_TOKEN }}
+
+      - name: Snyk security scan
+        uses: snyk/actions/python@master
+        continue-on-error: true
+        env:
+          SNYK_TOKEN: ${{ secrets.SNYK_TOKEN }}
+        with:
+          args: --file=requirements.txt --severity-threshold=high
+
+  docker:
+    name: Build & Push Docker
+    needs: test
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push'
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Generate CalVer tag
+        id: version
+        run: echo "TAG=$(date +%Y.%m).${{ github.run_number }}" >> "$GITHUB_OUTPUT"
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: app_python
+          push: true
+          tags: |
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-info-service:${{ steps.version.outputs.TAG }}
+            ${{ secrets.DOCKERHUB_USERNAME }}/devops-info-service:latest

.gitignore

@@ -1 +1,2 @@
-test
+test
+pyrightconfig.json

app_go/.dockerignore

@@ -0,0 +1,10 @@
+devops-info-service
+.git/
+.gitignore
+.vscode/
+.idea/
+*.md
+docs/
+.DS_Store
+Dockerfile
+.dockerignore

app_go/.gitignore

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+# Binary
+devops-info-service
+*.exe
+
+# IDE
+.idea/
+.vscode/
+
+# OS
+.DS_Store

app_go/Dockerfile

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+FROM golang:1.21-alpine AS builder
+
+WORKDIR /build
+
+COPY go.mod .
+COPY main.go .
+
+RUN CGO_ENABLED=0 GOOS=linux go build -o devops-info-service
+
+FROM scratch
+
+COPY --from=builder /build/devops-info-service /devops-info-service
+
+EXPOSE 8080
+
+ENTRYPOINT ["/devops-info-service"]

app_go/README.md

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+# DevOps Info Service (Go)
+
+A web service that reports system information and health status, built with Go's standard library `net/http`.
+
+## Prerequisites
+
+- Go 1.21+
+
+## Build
+
+```bash
+go build -o devops-info-service
+```
+
+## Running the Application
+
+```bash
+./devops-info-service
+```
+
+With custom configuration:
+
+```bash
+PORT=3000 ./devops-info-service
+HOST=127.0.0.1 PORT=3000 ./devops-info-service
+```
+
+Or run directly without building:
+
+```bash
+go run main.go
+```
+
+The service starts on `http://localhost:8080` by default.
+
+## API Endpoints
+
+| Method | Path      | Description                          |
+|--------|-----------|--------------------------------------|
+| GET    | `/`       | Service and system information       |
+| GET    | `/health` | Health check (status, uptime)        |
+
+### `GET /`
+
+```bash
+curl http://localhost:8080/
+```
+
+### `GET /health`
+
+```bash
+curl http://localhost:8080/health
+```
+
+## Configuration
+
+| Variable | Default   | Description          |
+|----------|-----------|----------------------|
+| `HOST`   | `0.0.0.0` | Server bind address  |
+| `PORT`   | `8080`    | Server port          |
+
+## Binary Size Comparison
+
+| Artifact             | Size     |
+|----------------------|----------|
+| Python (source)      | ~5 KB    |
+| Go (compiled binary) | ~7 MB    |
+
+The Go binary is self-contained — no runtime, no dependencies, no virtual environment needed. Just copy and run.

app_go/docs/GO.md

@@ -0,0 +1,28 @@
+# Language Justification: Go
+
+## Why Go
+
+| Criteria            | Python (FastAPI) | Go (net/http)      | Java (Spring Boot) |
+|---------------------|------------------|---------------------|---------------------|
+| Binary size         | N/A (interpreted)| ~7 MB               | ~20 MB (fat JAR)    |
+| Startup time        | ~1s              | Instant             | ~2-3s               |
+| Dependencies        | pip + venv       | Zero (stdlib only)  | Maven + JDK         |
+| Compilation speed   | N/A              | Very fast           | Moderate            |
+| Memory usage        | Moderate         | Very low            | High                |
+| Concurrency         | GIL-limited      | Goroutines (native) | Threads             |
+
+## Reasons for Choosing Go
+
+1. **Zero external dependencies** — the entire service is built using Go's standard library (`net/http`, `encoding/json`, `runtime`). No frameworks, no package managers, no dependency hell.
+
+2. **Single static binary** — `go build` produces one executable with everything baked in. No runtime needed, no JVM, no interpreter. Just copy the binary and run it anywhere.
+
+3. **Ideal for Docker** — small binary size and no runtime dependencies make for minimal Docker images. A multi-stage build with `FROM scratch` can produce images under 10 MB.
+
+4. **Fast compilation** — the entire project compiles in under a second, making the development loop fast.
+
+## Trade-offs
+
+- **Verbosity** — Go requires explicit struct definitions with JSON tags. More typing than Python dicts, but safer.
+- **No auto-docs** — unlike FastAPI's built-in Swagger, Go's stdlib has no API documentation generation.
+- **Error handling** — Go uses explicit `if err != nil` patterns instead of exceptions. More boilerplate but more predictable.

app_go/docs/LAB01.md

@@ -0,0 +1,42 @@
+# Lab 01 — DevOps Info Service (Go)
+
+## Implementation Details
+
+The Go implementation keeps everything in a single `main.go` file using only the standard library. This is idiomatic for small Go services — no need for a framework.
+
+**Key components:**
+- Struct types with JSON tags for response serialization
+- `rootHandler` and `healthHandler` for the two endpoints
+- `getUptime()` and `getHostname()` helper functions
+- `startTime` package-level variable for uptime tracking
+
+## Key Differences from Python Version
+
+| Aspect          | Python (FastAPI)           | Go (net/http)              |
+|-----------------|----------------------------|----------------------------|
+| Models          | Pydantic `BaseModel`       | Structs with JSON tags     |
+| Routing         | `@router.get("/")`         | `http.HandleFunc("/", fn)` |
+| JSON            | Automatic from dict/model  | `json.NewEncoder().Encode` |
+| Server          | uvicorn (external)         | Built-in `http.ListenAndServe` |
+| Dependencies    | fastapi, uvicorn           | None (stdlib only)         |
+| Field naming    | `python_version`           | `go_version`               |
+
+## Build & Run
+
+```bash
+go build -o devops-info-service
+./devops-info-service
+```
+
+## Testing
+
+```bash
+curl http://localhost:8080/
+curl http://localhost:8080/health
+```
+
+## Screenshots
+
+Screenshots in `screenshots/`:
+- Compilation and binary output
+- Running application with endpoint responses