Implementation of Lab11 Kubernetes Secrets and HashiCorp Vault

app_python/README.md

@@ -4,7 +4,7 @@
 
 [![python-ci](https://github.com/GrayMansion/DevOps-Core-Course/actions/workflows/python-ci.yml/badge.svg)](https://github.com/GrayMansion/DevOps-Core-Course/actions/workflows/python-ci.yml)
 
-A small web service that exposes system/runtime information and a health check endpoint.
+A small web service that exposes system/runtime information, metrics, and a persistent visits counter.
 
 ## Prerequisites
 - Python 3.11+
@@ -32,7 +32,9 @@ DEBUG=true python app.py
 ## API Endpoints
 ```bash
 GET / — Service and system information
+GET /visits — Current visits counter value
 GET /health — Health check
+GET /metrics — Prometheus metrics
 ```
 
 ## Configuration
@@ -41,6 +43,7 @@ GET /health — Health check
 | HOST     | 0.0.0.0 | Bind address                            |
 | PORT     | 5000    | Listening port                          |
 | DEBUG    | False   | If true, enables reload + debug logging |
+| VISITS_FILE | ./data/visits | File path for persistent visits counter |
 
 ## Docker
 
@@ -64,3 +67,22 @@ docker pull graymansion/devops-info-service:lab02
 docker run --rm -p <host_port>:<container_port> graymansion/devops-info-service:lab02
 ```
 
+## Local persistence test with Docker Compose
+
+Run from app_python directory:
+
+```bash
+docker compose up --build -d
+curl http://localhost:5000/
+curl http://localhost:5000/
+curl http://localhost:5000/visits
+cat ./data/visits
+docker compose restart
+curl http://localhost:5000/visits
+docker compose down
+```
+
+Expected result:
+- Counter increments when / is called.
+- The same counter value is kept after container restart because ./data is mounted to /app/data.
+

app_python/app.py

@@ -9,6 +9,8 @@
 import platform
 import socket
 import time
+from pathlib import Path
+from threading import Lock
 from datetime import datetime, timezone
 
 import uvicorn
@@ -24,6 +26,7 @@
 PORT = int(os.getenv("PORT", "5000"))
 DEBUG = os.getenv("DEBUG", "False").lower() == "true"
 LOG_FORMAT = os.getenv("LOG_FORMAT", "text")  # "json" for structured logging
+VISITS_FILE = os.getenv("VISITS_FILE", "./data/visits")
 
 
 # -------------------------
@@ -97,6 +100,35 @@ def format(self, record: logging.LogRecord) -> str:
     "System info collection duration in seconds",
 )
 
+VISITS_LOCK = Lock()
+
+
+def read_visits() -> int:
+    visits_path = Path(VISITS_FILE)
+    try:
+        raw_value = visits_path.read_text(encoding="utf-8").strip()
+        return int(raw_value) if raw_value else 0
+    except FileNotFoundError:
+        return 0
+    except ValueError:
+        logger.warning("Invalid visits counter content in %s, resetting to 0", visits_path)
+        return 0
+
+
+def write_visits(value: int) -> int:
+    visits_path = Path(VISITS_FILE)
+    visits_path.parent.mkdir(parents=True, exist_ok=True)
+    tmp_path = visits_path.with_name(f"{visits_path.name}.tmp")
+    tmp_path.write_text(str(value), encoding="utf-8")
+    tmp_path.replace(visits_path)
+    return value
+
+
+def increment_visits() -> int:
+    with VISITS_LOCK:
+        visits = read_visits() + 1
+        return write_visits(visits)
+
 
 def iso_utc_now() -> str:
     # Example desired format: 2026-01-07T14:30:00.000Z
@@ -136,6 +168,14 @@ def get_system_info() -> dict:
     }
 
 
+@app.on_event("startup")
+async def initialize_visits_counter() -> None:
+    with VISITS_LOCK:
+        current_visits = read_visits()
+        write_visits(current_visits)
+    logger.info("Visits counter initialized at %d in %s", current_visits, VISITS_FILE)
+
+
 @app.exception_handler(StarletteHTTPException)
 async def http_exception_handler(_: Request, exc: StarletteHTTPException):
     if exc.status_code == 404:
@@ -202,6 +242,7 @@ async def log_requests(request: Request, call_next):
 @app.get("/")
 async def index(request: Request) -> dict:
     ENDPOINT_CALLS.labels(endpoint="/").inc()
+    visits = increment_visits()
     uptime = get_uptime()
     with SYSTEM_INFO_DURATION_SECONDS.time():
         system_info = get_system_info()
@@ -226,14 +267,25 @@ async def index(request: Request) -> dict:
             "method": request.method,
             "path": request.url.path,
         },
+        "stats": {
+            "visits": visits,
+        },
         "endpoints": [
             {"path": "/", "method": "GET", "description": "Service information"},
+            {"path": "/visits", "method": "GET", "description": "Current visits count"},
             {"path": "/health", "method": "GET", "description": "Health check"},
             {"path": "/metrics", "method": "GET", "description": "Prometheus metrics"},
         ],
     }
 
 
+@app.get("/visits")
+async def visits() -> dict:
+    ENDPOINT_CALLS.labels(endpoint="/visits").inc()
+    with VISITS_LOCK:
+        return {"visits": read_visits()}
+
+
 @app.get("/health")
 async def health() -> dict:
     ENDPOINT_CALLS.labels(endpoint="/health").inc()

app_python/docker-compose.yml

@@ -0,0 +1,17 @@
+version: "3.9"
+
+services:
+  devops-info:
+    build:
+      context: .
+      dockerfile: Dockerfile
+    container_name: devops-info
+    ports:
+      - "5000:5000"
+    environment:
+      HOST: "0.0.0.0"
+      PORT: "5000"
+      DEBUG: "false"
+      VISITS_FILE: "/app/data/visits"
+    volumes:
+      - ./data:/app/data

app_python/tests/test_app.py

@@ -1,9 +1,41 @@
+import app as app_module
+import pytest
 from fastapi.testclient import TestClient
 
 from app import app
 
 client = TestClient(app)
 
+
+@pytest.fixture(autouse=True)
+def isolated_visits_file(tmp_path, request):
+    app_module.VISITS_FILE = str(tmp_path / f"{request.node.name}.visits")
+
+
+def test_visits_counter_persists_in_file(tmp_path):
+    visits_file = tmp_path / "visits"
+    app_module.VISITS_FILE = str(visits_file)
+
+    first = client.get("/")
+    second = client.get("/")
+    assert first.status_code == 200
+    assert second.status_code == 200
+
+    assert first.json()["stats"]["visits"] == 1
+    assert second.json()["stats"]["visits"] == 2
+    assert visits_file.read_text(encoding="utf-8").strip() == "2"
+
+
+def test_visits_endpoint_reads_current_count(tmp_path):
+    visits_file = tmp_path / "visits"
+    visits_file.write_text("7", encoding="utf-8")
+    app_module.VISITS_FILE = str(visits_file)
+
+    response = client.get("/visits")
+    assert response.status_code == 200
+    assert response.json() == {"visits": 7}
+
+
 def test_root_structure():
     r = client.get("/", headers={"User-Agent": "pytest"})
     assert r.status_code == 200
@@ -20,13 +52,15 @@ def test_root_structure():
 
     assert isinstance(data["runtime"]["uptime_seconds"], int)
     assert data["runtime"]["timezone"] == "UTC"
+    assert isinstance(data["stats"]["visits"], int)
 
     assert data["request"]["method"] == "GET"
     assert data["request"]["path"] == "/"
     assert data["request"]["user_agent"] is not None
 
     paths = {e["path"] for e in data["endpoints"]}
-    assert "/" in paths and "/health" in paths
+    assert "/" in paths and "/health" in paths and "/visits" in paths
+
 
 def test_health():
     r = client.get("/health")
@@ -36,6 +70,7 @@ def test_health():
     assert isinstance(data["uptime_seconds"], int)
     assert "timestamp" in data
 
+
 def test_404_json():
     r = client.get("/nope")
     assert r.status_code == 404
@@ -46,6 +81,7 @@ def test_404_json():
 def test_metrics_endpoint():
     client.get("/")
     client.get("/health")
+    client.get("/visits")
 
     r = client.get("/metrics")
     assert r.status_code == 200
@@ -58,3 +94,4 @@ def test_metrics_endpoint():
     assert "devops_info_endpoint_calls_total" in body
     assert 'endpoint="/"' in body
     assert 'endpoint="/health"' in body
+    assert 'endpoint="/visits"' in body