added lab12 solution

app_python/.gitignore

@@ -1,13 +1,16 @@
-# Python
-__pycache__/
-*.py[cod]
-venv/
-*.log
-.env
-
-# IDE
-.vscode/
-.idea/
-
-# OS
-.DS_Store
+# Python
+__pycache__/
+*.py[cod]
+venv/
+*.log
+.env
+
+# IDE
+.vscode/
+.idea/
+
+# OS
+.DS_Store
+
+# Local persistence data
+data/

app_python/Dockerfile

@@ -10,7 +10,9 @@ WORKDIR /app
 
 # Create a dedicated non-root user with numeric UID/GID.
 RUN addgroup --system --gid 10001 app \
-    && adduser --system --uid 10001 --ingroup app --no-create-home app
+    && adduser --system --uid 10001 --ingroup app --no-create-home app \
+    && mkdir -p /data /config \
+    && chown -R 10001:10001 /app /data /config
 
 # Install dependencies first to leverage Docker layer caching.
 COPY requirements.txt ./

app_python/README.md

@@ -3,13 +3,15 @@
 [![python-ci](https://github.com/dorley174/DevOps-Core-Course/actions/workflows/python-ci.yml/badge.svg)](https://github.com/dorley174/DevOps-Core-Course/actions/workflows/python-ci.yml)
 
 ## Overview
-DevOps Info Service is a production-ready starter web service for the DevOps course.  
-It reports service metadata, runtime details, and basic system information.
+DevOps Info Service is a production-ready starter web service for the DevOps course.
+It reports service metadata, runtime details, basic system information, and a persisted visit counter.
 
-The service exposes two endpoints:
-- `GET /` — service + system + runtime + request information
+The service exposes these endpoints:
+- `GET /` — service + system + runtime + request information and increments the persisted visit counter
+- `GET /visits` — returns the current visit counter without incrementing it
 - `GET /health` — liveness health endpoint
 - `GET /ready` — readiness health endpoint for Kubernetes
+- `GET /metrics` — Prometheus metrics endpoint
 
 ## Prerequisites
 - Python **3.11+**
@@ -39,14 +41,15 @@ python app.py
 
 **Linux/Mac:**
 ```bash
-HOST=127.0.0.1 PORT=8080 DEBUG=True python app.py
+HOST=127.0.0.1 PORT=8080 DEBUG=True VISITS_FILE=./data/visits python app.py
 ```
 
 **Windows (PowerShell):**
 ```powershell
 $env:HOST="127.0.0.1"
 $env:PORT="8080"
 $env:DEBUG="True"
+$env:VISITS_FILE="./data/visits"
 python app.py
 ```
 
@@ -55,19 +58,29 @@ python app.py
 set HOST=127.0.0.1
 set PORT=8080
 set DEBUG=True
+set VISITS_FILE=./data/visits
 python app.py
 ```
 
 ## API Endpoints
 
 ### `GET /`
-Returns service metadata, system information, runtime details, request info, and a list of available endpoints.
+Returns service metadata, system information, runtime details, request info, runtime configuration, and the current visit count.
+Each request to `/` increments the persisted counter stored in `VISITS_FILE`.
 
 Example:
 ```bash
 curl http://127.0.0.1:5000/
 ```
 
+### `GET /visits`
+Returns the current counter value without incrementing it.
+
+Example:
+```bash
+curl http://127.0.0.1:5000/visits
+```
+
 ### `GET /health`
 Returns a minimal liveness response for monitoring and Kubernetes liveness probes.
 
@@ -84,6 +97,37 @@ Example:
 curl -i http://127.0.0.1:5000/ready
 ```
 
+## Local Persistence Testing with Docker Compose
+
+A `docker-compose.yml` file is provided to verify that the visits counter survives container restarts.
+
+### Start the service
+```bash
+mkdir -p data
+docker compose up --build -d
+```
+
+### Generate visits
+```bash
+curl http://127.0.0.1:5000/
+curl http://127.0.0.1:5000/
+curl http://127.0.0.1:5000/visits
+cat ./data/visits
+```
+
+### Restart and verify persistence
+```bash
+docker compose restart
+docker compose ps
+curl http://127.0.0.1:5000/visits
+cat ./data/visits
+```
+
+### Stop the stack
+```bash
+docker compose down
+```
+
 ## Testing / Pretty Output
 
 ### Pretty-printed JSON
@@ -125,9 +169,14 @@ Add:
 
 | Variable | Default | Description |
 |----------|---------|-------------|
-| HOST     | 0.0.0.0 | Bind address |
-| PORT     | 5000    | HTTP port |
-| DEBUG    | False   | Flask debug mode |
+| HOST | `0.0.0.0` | Bind address |
+| PORT | `5000` | HTTP port |
+| DEBUG | `False` | Flask debug mode |
+| VISITS_FILE | `/data/visits` | File used to persist the visit counter |
+| APP_ENV | `dev` | Runtime environment value |
+| LOG_LEVEL | `INFO` | Application log level metadata |
+| CONFIG_FILE_PATH | `/config/config.json` | Mounted ConfigMap file path |
+| FEATURE_VISITS_ENDPOINT | `true` | Feature flag exposed through environment variables |
 
 ---
 
@@ -144,25 +193,20 @@ docker build -t <image>:<tag> .
 ### Run
 
 ```bash
-docker run --rm -p 5000:5000 <image>:<tag>
-```
-
-(Optional: override env vars)
-
-```bash
-docker run --rm -p 5000:5000 -e PORT=5000 -e DEBUG=false <image>:<tag>
+docker run --rm -p 5000:5000 -e VISITS_FILE=/data/visits -v $(pwd)/data:/data <image>:<tag>
 ```
 
 ### Pull from Docker Hub
 
 ```bash
 docker pull <dockerhub-username>/<repo>:<tag>
-docker run --rm -p 5000:5000 <dockerhub-username>/<repo>:<tag>
+docker run --rm -p 5000:5000 -e VISITS_FILE=/data/visits -v $(pwd)/data:/data <dockerhub-username>/<repo>:<tag>
 ```
 
 ### Quick test
 
 ```bash
 curl http://localhost:5000/health
 curl http://localhost:5000/
+curl http://localhost:5000/visits
 ```

app_python/app.py

@@ -6,6 +6,7 @@
 - GET /        : service + system + runtime + request info
 - GET /health  : health check (for probes/monitoring)
 - GET /metrics : Prometheus metrics endpoint
+- GET /visits  : current persisted visit counter value
 """
 
 from __future__ import annotations
@@ -16,8 +17,11 @@
 import platform
 import socket
 import sys
+import tempfile
+import threading
 import time
 from datetime import datetime, timezone
+from pathlib import Path
 from typing import Any, Dict
 
 from flask import Flask, Response, g, jsonify, request
@@ -39,8 +43,14 @@
 SERVICE_FRAMEWORK = "Flask"
 APP_VARIANT = os.getenv("APP_VARIANT", "primary")
 APP_MESSAGE = os.getenv("APP_MESSAGE", "running")
+APP_ENV = os.getenv("APP_ENV", "dev")
+LOG_LEVEL = os.getenv("LOG_LEVEL", "INFO")
+FEATURE_VISITS_ENDPOINT = os.getenv("FEATURE_VISITS_ENDPOINT", "true")
+CONFIG_FILE_PATH = os.getenv("CONFIG_FILE_PATH", "/config/config.json")
+VISITS_FILE = Path(os.getenv("VISITS_FILE", "/data/visits"))
 
 START_TIME_UTC = datetime.now(timezone.utc)
+VISITS_LOCK = threading.Lock()
 
 
 # -----------------------------------------------------------------------------
@@ -164,6 +174,7 @@ def get_client_ip() -> str:
     return request.remote_addr or "unknown"
 
 
+
 def normalize_endpoint() -> str:
     """
     Keep endpoint labels low-cardinality for Prometheus.
@@ -289,15 +300,102 @@ def get_system_info() -> Dict[str, Any]:
 
 
 
+def ensure_visits_storage() -> int:
+    """Create the visits file if missing and return the initial counter value."""
+    VISITS_FILE.parent.mkdir(parents=True, exist_ok=True)
+    if not VISITS_FILE.exists():
+        write_visits_count(0)
+        return 0
+    return read_visits_count()
+
+
+
+def read_visits_count() -> int:
+    """Read the persisted visit counter from disk."""
+    try:
+        content = VISITS_FILE.read_text(encoding="utf-8").strip()
+    except FileNotFoundError:
+        return 0
+
+    if not content:
+        return 0
+
+    try:
+        return int(content)
+    except ValueError:
+        logger.warning(
+            "invalid_visits_file_content",
+            extra={
+                "event": "invalid_visits_file_content",
+                "service": SERVICE_NAME,
+                "version": SERVICE_VERSION,
+            },
+        )
+        return 0
+
+
+
+def write_visits_count(value: int) -> None:
+    """Persist the visit counter using an atomic replace operation."""
+    VISITS_FILE.parent.mkdir(parents=True, exist_ok=True)
+    with tempfile.NamedTemporaryFile("w", encoding="utf-8", dir=str(VISITS_FILE.parent), delete=False) as handle:
+        handle.write(str(value))
+        handle.flush()
+        os.fsync(handle.fileno())
+        temp_path = Path(handle.name)
+
+    os.replace(temp_path, VISITS_FILE)
+
+
+
+def increment_visits_count() -> int:
+    """Read, increment, and persist the visit counter with in-process locking."""
+    with VISITS_LOCK:
+        current_value = read_visits_count()
+        next_value = current_value + 1
+        write_visits_count(next_value)
+        return next_value
+
+
+
+def get_runtime_config() -> Dict[str, Any]:
+    """Return file-based and environment-based configuration details."""
+    config_payload: Dict[str, Any] = {
+        "app_env": APP_ENV,
+        "log_level": LOG_LEVEL,
+        "feature_visits_endpoint": FEATURE_VISITS_ENDPOINT,
+        "config_file_path": CONFIG_FILE_PATH,
+        "config_file_loaded": False,
+    }
+
+    config_path = Path(CONFIG_FILE_PATH)
+    if not config_path.exists():
+        config_payload["config_file_error"] = "config file not found"
+        return config_payload
+
+    try:
+        config_payload["config_file"] = json.loads(config_path.read_text(encoding="utf-8"))
+        config_payload["config_file_loaded"] = True
+    except (OSError, json.JSONDecodeError) as exc:
+        config_payload["config_file_error"] = str(exc)
+
+    return config_payload
+
+
+
 def build_endpoints() -> list[Dict[str, str]]:
     return [
-        {"path": "/", "method": "GET", "description": "Service information"},
+        {"path": "/", "method": "GET", "description": "Service information and visit counter increment"},
+        {"path": "/visits", "method": "GET", "description": "Current persisted visit count"},
         {"path": "/health", "method": "GET", "description": "Liveness health check"},
         {"path": "/ready", "method": "GET", "description": "Readiness health check"},
         {"path": "/metrics", "method": "GET", "description": "Prometheus metrics"},
     ]
 
 
+INITIAL_VISITS = ensure_visits_storage()
+
+
 # -----------------------------------------------------------------------------
 # Routes
 # -----------------------------------------------------------------------------
@@ -306,6 +404,7 @@ def build_endpoints() -> list[Dict[str, str]]:
 def index():
     """Main endpoint - service and system information."""
     uptime = get_uptime()
+    current_visits = increment_visits_count()
 
     payload: Dict[str, Any] = {
         "service": {
@@ -329,12 +428,32 @@ def index():
             "method": request.method,
             "path": request.path,
         },
+        "visits": {
+            "count": current_visits,
+            "file": str(VISITS_FILE),
+        },
+        "configuration": get_runtime_config(),
         "endpoints": build_endpoints(),
     }
 
     return jsonify(payload), 200
 
 
+@app.get("/visits")
+def visits():
+    """Return the current persisted visit counter without incrementing it."""
+    with VISITS_LOCK:
+        current_visits = read_visits_count()
+
+    return jsonify(
+        {
+            "visits": current_visits,
+            "file": str(VISITS_FILE),
+            "timestamp": iso_utc_now_z(),
+        }
+    ), 200
+
+
 @app.get("/health")
 def health():
     """Health check endpoint (for probes/monitoring)."""
@@ -442,10 +561,12 @@ def main() -> None:
         },
     )
     logger.info(
-        "runtime_configuration host=%s port=%s debug=%s",
+        "runtime_configuration host=%s port=%s debug=%s visits_file=%s initial_visits=%s",
         HOST,
         PORT,
         DEBUG,
+        VISITS_FILE,
+        INITIAL_VISITS,
         extra={
             "event": "runtime_configuration",
             "service": SERVICE_NAME,