docs(lab8): submit Lab 8 — SRE & Monitoring

.github/pull_request_template.md

@@ -0,0 +1,13 @@
+## Goal
+<!-- What does this PR accomplish? 1 sentence. -->
+
+## Changes
+- 
+
+## Testing
+<!-- How did you verify it? -->
+
+## Checklist
+- [ ] Title is a clear sentence (≤ 70 chars)
+- [ ] Commits are signed (`git log --show-signature`)
+- [ ] `submissions/labN.md` updated

.github/workflows/ci.yml

@@ -0,0 +1,57 @@
+name: PR Gate
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+    paths:
+      - 'app/**'
+      - '.github/workflows/ci.yml'
+
+permissions:
+  contents: read
+
+jobs:
+  vet:
+    runs-on: ubuntu-24.04
+    strategy:
+      matrix:
+        go-version: ['1.23', '1.24']
+      fail-fast: false
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/setup-go@f111f3307d8850f501ac008e886eec1fd1932a34
+        with:
+          go-version: ${{ matrix.go-version }}
+          cache: true
+      - run: go vet ./...
+        working-directory: app
+
+  test:
+    runs-on: ubuntu-24.04
+    strategy:
+      matrix:
+        go-version: ['1.23', '1.24']
+      fail-fast: false
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/setup-go@f111f3307d8850f501ac008e886eec1fd1932a34
+        with:
+          go-version: ${{ matrix.go-version }}
+          cache: true
+      - run: go test -race -count=1 ./...
+        working-directory: app
+
+  lint:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+      - uses: actions/setup-go@f111f3307d8850f501ac008e886eec1fd1932a34
+        with:
+          go-version: '1.24'
+          cache: true
+      - uses: golangci/golangci-lint-action@971e284b6050e8a5849b72094c50ab08da042db8
+        with:
+          version: v2.5.0
+          working-directory: app

Vagrantfile

@@ -0,0 +1,31 @@
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/jammy64"
+  config.vm.hostname = "quicknotes-vm"
+
+  config.vm.network "forwarded_port", 
+    guest: 8080, 
+    host: 18080, 
+    host_ip: "127.0.0.1"
+
+  config.vm.synced_folder "./app", "/home/vagrant/app"
+
+  config.vm.provider "virtualbox" do |vb|
+    vb.memory = 1024
+    vb.cpus = 2
+  end
+
+  config.vm.provision "shell", inline: <<-SHELL
+    apt-get update
+    apt-get install -y wget curl
+
+    wget https://go.dev/dl/go1.24.5.linux-amd64.tar.gz
+    tar -C /usr/local -xzf go1.24.5.linux-amd64.tar.gz
+    echo 'export PATH=/usr/local/go/bin:$PATH' >> /home/vagrant/.bashrc
+
+    cd /home/vagrant/app
+    /usr/local/go/bin/go build -o /home/vagrant/app/server .
+    nohup /home/vagrant/app/server > /home/vagrant/server.log 2>&1 &
+
+    echo "Server started on port 8080"
+  SHELL
+end

ansible/inventory.ini

@@ -0,0 +1,5 @@
+[lab5_vm]
+quicknotes-vm ansible_host=127.0.0.1 ansible_port=2222 ansible_user=vagrant ansible_private_key_file=/home/ksu/lab5/.vagrant/machines/default/virtualbox/private_key ansible_ssh_extra_args='-o StrictHostKeyChecking=no'
+
+[all:vars]
+ansible_python_interpreter=/usr/bin/python3

ansible/playbook.yaml

@@ -0,0 +1,70 @@
+---
+- name: Deploy QuickNotes to Lab 5 VM
+  hosts: lab5_vm
+  become: true
+  gather_facts: true
+
+  vars:
+    quicknotes_user: quicknotes
+    quicknotes_group: quicknotes
+    quicknotes_data_dir: /var/lib/quicknotes
+    quicknotes_bin_path: /usr/local/bin/quicknotes
+    quicknotes_listen_addr: ":9091"
+    quicknotes_seed_path: /var/lib/quicknotes/seed.json
+
+  tasks:
+    - name: Create quicknotes system group
+      ansible.builtin.group:
+        name: "{{ quicknotes_group }}"
+        system: true
+        state: present
+
+    - name: Create quicknotes system user
+      ansible.builtin.user:
+        name: "{{ quicknotes_user }}"
+        group: "{{ quicknotes_group }}"
+        system: true
+        shell: /usr/sbin/nologin
+        create_home: false
+        state: present
+
+    - name: Create data directory
+      ansible.builtin.file:
+        path: "{{ quicknotes_data_dir }}"
+        owner: "{{ quicknotes_user }}"
+        group: "{{ quicknotes_group }}"
+        mode: '0750'
+        state: directory
+
+    - name: Copy QuickNotes binary
+      ansible.builtin.copy:
+        src: files/quicknotes
+        dest: "{{ quicknotes_bin_path }}"
+        mode: '0755'
+        owner: root
+        group: root
+      notify: restart quicknotes
+
+    - name: Render systemd service unit
+      ansible.builtin.template:
+        src: templates/quicknotes.service.j2
+        dest: /etc/systemd/system/quicknotes.service
+        mode: '0644'
+        owner: root
+        group: root
+      notify: restart quicknotes
+
+    - name: Reload systemd and start service
+      ansible.builtin.systemd:
+        daemon_reload: true
+        name: quicknotes
+        state: started
+        enabled: true
+
+  handlers:
+    - name: restart quicknotes
+      ansible.builtin.systemd:
+        name: quicknotes
+        state: restarted
+        daemon_reload: true
+

ansible/templates/quicknotes.service.j2

@@ -0,0 +1,20 @@
+[Unit]
+Description=QuickNotes Service
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+User={{ quicknotes_user }}
+Group={{ quicknotes_group }}
+WorkingDirectory={{ quicknotes_data_dir }}
+Environment=ADDR={{ quicknotes_listen_addr }}
+Environment=DATA_PATH={{ quicknotes_data_dir }}
+Environment=SEED_PATH={{ quicknotes_seed_path }}
+ExecStart={{ quicknotes_bin_path }}
+Restart=on-failure
+RestartSec=5s
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=multi-user.target

app/Dockerfile

@@ -0,0 +1,18 @@
+FROM golang:1.24-alpine AS builder
+
+WORKDIR /app
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -trimpath -o /quicknotes .
+
+FROM gcr.io/distroless/static:nonroot
+
+COPY --from=builder /quicknotes /quicknotes
+
+EXPOSE 8080
+HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 \
+  CMD ["/quicknotes", "-health"]
+
+ENTRYPOINT ["/quicknotes"]

app/main.go

@@ -1,85 +1,94 @@
 package main
 
 import (
-	"context"
-	"errors"
+	"encoding/json"
+	"fmt"
 	"log"
 	"net/http"
 	"os"
-	"os/signal"
-	"syscall"
-	"time"
 )
 
-func main() {
-	addr := envOrDefault("ADDR", ":8080")
-	dataPath := envOrDefault("DATA_PATH", "data/notes.json")
-	seedPath := envOrDefault("SEED_PATH", "seed.json")
+type Note struct {
+	ID      int    `json:"id"`
+	Title   string `json:"title"`
+	Content string `json:"content"`
+}
 
-	if err := ensureSeeded(dataPath, seedPath); err != nil {
-		log.Fatalf("seed: %v", err)
-	}
+var notes = []Note{
+	{ID: 1, Title: "Welcome", Content: "Welcome to QuickNotes!"},
+	{ID: 2, Title: "Getting Started", Content: "This is your first note"},
+}
+var nextID = 3
 
-	store, err := NewStore(dataPath)
-	if err != nil {
-		log.Fatalf("store: %v", err)
+func main() {
+	// Get port from environment variable, default to :8080
+	addr := os.Getenv("ADDR")
+	if addr == "" {
+		addr = ":8080"
 	}
 
-	server := NewServer(store)
-	srv := &http.Server{
-		Addr:              addr,
-		Handler:           server.Routes(),
-		ReadHeaderTimeout: 5 * time.Second,
+	// Get data path from environment variable
+	dataPath := os.Getenv("DATA_PATH")
+	if dataPath == "" {
+		dataPath = "/var/lib/quicknotes"
 	}
 
-	go func() {
-		log.Printf("quicknotes listening on %s (notes loaded: %d)", addr, store.Count())
-		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
-			log.Fatalf("listen: %v", err)
-		}
-	}()
+	// Routes
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "Hello from QuickNotes!\n")
+	})
 
-	stop := make(chan os.Signal, 1)
-	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
-	<-stop
-	log.Println("shutting down")
+	http.HandleFunc("/health", healthHandler)
+	http.HandleFunc("/notes", notesHandler)
+	http.HandleFunc("/notes/", noteHandler)
 
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
-	if err := srv.Shutdown(ctx); err != nil {
-		log.Printf("shutdown: %v", err)
-	}
+	log.Printf("Server listening on %s (DATA_PATH=%s)", addr, dataPath)
+	log.Fatal(http.ListenAndServe(addr, nil))
 }
 
-func envOrDefault(k, def string) string {
-	if v, ok := os.LookupEnv(k); ok && v != "" {
-		return v
-	}
-	return def
+func healthHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(map[string]interface{}{
+		"status": "ok",
+		"notes":  len(notes),
+	})
 }
 
-func ensureSeeded(dataPath, seedPath string) error {
-	if _, err := os.Stat(dataPath); err == nil {
-		return nil
-	}
-	if err := os.MkdirAll(dirname(dataPath), 0o755); err != nil {
-		return err
-	}
-	seed, err := os.ReadFile(seedPath)
-	if err != nil {
-		if errors.Is(err, os.ErrNotExist) {
-			return os.WriteFile(dataPath, []byte("[]"), 0o644)
+func notesHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	switch r.Method {
+	case "GET":
+		json.NewEncoder(w).Encode(notes)
+	case "POST":
+		var note Note
+		if err := json.NewDecoder(r.Body).Decode(&note); err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
 		}
-		return err
+		note.ID = nextID
+		nextID++
+		notes = append(notes, note)
+		w.WriteHeader(http.StatusCreated)
+		json.NewEncoder(w).Encode(note)
+	default:
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
 	}
-	return os.WriteFile(dataPath, seed, 0o644)
 }
 
-func dirname(p string) string {
-	for i := len(p) - 1; i >= 0; i-- {
-		if p[i] == '/' {
-			return p[:i]
+func noteHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	// Parse ID from URL
+	var id int
+	if _, err := fmt.Sscanf(r.URL.Path, "/notes/%d", &id); err != nil {
+		http.Error(w, "Invalid ID", http.StatusBadRequest)
+		return
+	}
+
+	for _, note := range notes {
+		if note.ID == id {
+			json.NewEncoder(w).Encode(note)
+			return
 		}
 	}
-	return "."
+	http.Error(w, "Note not found", http.StatusNotFound)
 }