lab12: done

app_python/README.md

@@ -61,6 +61,16 @@ The service will start on `http://HOST:PORT` (default `0.0.0.0:5000`).
     curl http://127.0.0.1:5000/health
     ```
 
+- `GET /visits`
+  - **Description**: Returns the persistent visits counter (file-backed, survives restarts). Incremented on every `GET /` request.
+  - **Example**:
+    ```bash
+    curl http://127.0.0.1:5000/visits
+    ```
+
+- `GET /config`
+  - **Description**: Returns the JSON content of the mounted ConfigMap file at `$CONFIG_FILE` plus selected env vars sourced from a ConfigMap.
+
 ## Configuration
 
 The application is configurable via environment variables:
@@ -70,6 +80,8 @@ The application is configurable via environment variables:
 | `HOST`   | `0.0.0.0`   | Interface the server binds to               |
 | `PORT`   | `5000`      | TCP port the server listens on              |
 | `DEBUG`  | `False`     | Enables FastAPI/uvicorn reload when `true` |
+| `DATA_DIR` | `/data`   | Directory where the visits counter file is stored |
+| `CONFIG_FILE` | `/config/config.json` | Path to a JSON config file mounted via ConfigMap |
 
 Example:
 
@@ -118,6 +130,24 @@ ruff check .
 
 **Pull from Docker Hub:** `docker pull <your-dockerhub-username>/<repo-name>:<tag>` then run as above.
 
+### Docker Compose (persistent visits)
+
+A `docker-compose.yml` bind-mounts `./visits-data` into the container at `/app/data` so the
+visits counter survives container restarts.
+
+```bash
+cd app_python
+mkdir -p visits-data
+# container runs as non-root (uid 1000) so make the bind mount writable
+sudo chown -R 1000:1000 visits-data || true
+docker compose up --build -d
+curl -s http://127.0.0.1:5000/        # increments counter
+curl -s http://127.0.0.1:5000/visits  # read-only
+cat ./visits-data/visits               # counter is persisted on host
+docker compose restart devops-info
+curl -s http://127.0.0.1:5000/visits  # value is preserved across restart
+```
+
 ## CI/CD
 
 This project uses GitHub Actions for continuous integration and deployment:

app_python/app.py

@@ -5,25 +5,31 @@
 Now emits structured JSON logs for easier aggregation.
 """
 
+import asyncio
 import json
 import logging
 import os
 import platform
 import socket
+import tempfile
+from pathlib import Path
 from time import perf_counter
 from datetime import UTC, datetime
 from typing import Any
 
 import uvicorn
 from fastapi import FastAPI, Request, Response
 from fastapi.responses import JSONResponse
 from prometheus_client import CONTENT_TYPE_LATEST, Counter, Gauge, Histogram, generate_latest
 from starlette.exceptions import HTTPException as StarletteHTTPException
 
 # Configuration
 HOST: str = os.getenv("HOST", "0.0.0.0")
 PORT: int = int(os.getenv("PORT", 5000))
 DEBUG: bool = os.getenv("DEBUG", "False").lower() == "true"
+DATA_DIR: str = os.getenv("DATA_DIR", "/data")
+VISITS_FILE: Path = Path(DATA_DIR) / "visits"
+CONFIG_FILE: str = os.getenv("CONFIG_FILE", "/config/config.json")
 
 
 class JSONFormatter(logging.Formatter):
@@ -68,10 +74,52 @@
 
 app = FastAPI(title="DevOps Info Service")
 
+_visits_lock = asyncio.Lock()
+
+
+def _read_visits() -> int:
+    """Read visits counter from file, default to 0 if missing/invalid."""
+    try:
+        return int(VISITS_FILE.read_text().strip() or "0")
+    except (FileNotFoundError, ValueError):
+        return 0
+
+
+def _write_visits(value: int) -> None:
+    """Atomically write visits counter (tmp file + rename)."""
+    VISITS_FILE.parent.mkdir(parents=True, exist_ok=True)
+    fd, tmp_path = tempfile.mkstemp(dir=str(VISITS_FILE.parent), prefix=".visits.")
+    try:
+        with os.fdopen(fd, "w") as f:
+            f.write(str(value))
+        os.replace(tmp_path, VISITS_FILE)
+    except Exception:
+        try:
+            os.unlink(tmp_path)
+        except OSError:
+            pass
+        raise
+
+
+async def _increment_visits() -> int:
+    async with _visits_lock:
+        new_value = _read_visits() + 1
+        _write_visits(new_value)
+        return new_value
+
+
+def _load_config_file() -> dict[str, Any]:
+    """Best-effort read of the mounted ConfigMap config file."""
+    try:
+        with open(CONFIG_FILE) as f:
+            return json.load(f)
+    except (FileNotFoundError, json.JSONDecodeError):
+        return {}
+
 
 def normalize_endpoint(path: str) -> str:
     """Normalize endpoint labels to keep metric cardinality predictable."""
-    if path in {"/", "/health", "/metrics"}:
+    if path in {"/", "/health", "/metrics", "/visits", "/config"}:
         return path
     return "/other"
 
@@ -184,6 +232,8 @@
         {"path": "/", "method": "GET", "description": "Service information"},
         {"path": "/health", "method": "GET", "description": "Health check"},
         {"path": "/metrics", "method": "GET", "description": "Prometheus metrics"},
+        {"path": "/visits", "method": "GET", "description": "Persistent visits counter"},
+        {"path": "/config", "method": "GET", "description": "Mounted ConfigMap content"},
     ]
 
 
@@ -204,6 +254,7 @@
         system_info = get_system_info()
     runtime_info = get_runtime_info()
     request_info = get_request_info(request)
+    visits = await _increment_visits()
 
     response: dict[str, Any] = {
         "service": {
@@ -215,11 +266,35 @@
         "system": system_info,
         "runtime": runtime_info,
         "request": request_info,
+        "visits": visits,
         "endpoints": get_endpoints(),
     }
     return response
 
 
+@app.get("/visits")
+async def visits() -> dict[str, Any]:
+    """Return current persistent visits counter without incrementing."""
+    ENDPOINT_CALLS_TOTAL.labels(endpoint="/visits").inc()
+    return {"visits": _read_visits(), "file": str(VISITS_FILE)}
+
+
+@app.get("/config")
+async def config() -> dict[str, Any]:
+    """Return the mounted ConfigMap content and selected env vars."""
+    ENDPOINT_CALLS_TOTAL.labels(endpoint="/config").inc()
+    return {
+        "file_path": CONFIG_FILE,
+        "file_content": _load_config_file(),
+        "env": {
+            "APP_ENV": os.getenv("APP_ENV"),
+            "LOG_LEVEL": os.getenv("LOG_LEVEL"),
+            "FEATURE_FLAG_BETA": os.getenv("FEATURE_FLAG_BETA"),
+            "WELCOME_MESSAGE": os.getenv("WELCOME_MESSAGE"),
+        },
+    }
+
+
 @app.get("/health")
 async def health() -> dict[str, Any]:
     """Health check endpoint."""

app_python/docker-compose.yml

@@ -0,0 +1,15 @@
+services:
+  devops-info:
+    build: .
+    container_name: devops-info
+    ports:
+      - "5000:5000"
+    environment:
+      HOST: "0.0.0.0"
+      PORT: "5000"
+      DATA_DIR: "/app/data"
+      APP_ENV: "local"
+      LOG_LEVEL: "info"
+    volumes:
+      - ./visits-data:/app/data
+    restart: unless-stopped

app_python/visits-data/visits

@@ -0,0 +1 @@
+11