Fixed error message about Docker daemon not running and added requirements to readme

Author: dementii-priadko

README.md

@@ -4,8 +4,35 @@ A complete PostgreSQL monitoring solution with automated performance analysis an
 
 ## 📋 Requirements
 
+**Infrastructure:**
+- **Linux machine** with Docker installed (separate from your database server)
+- **Docker access** - the user running `postgres_ai` must have Docker permissions
+- **Network access** to the PostgreSQL database(s) you want to monitor
+
+**Database:**
 - Supports PostgreSQL versions 14-17
 
+## ⚠️ Security Notice
+
+**WARNING: Security is your responsibility!**
+
+This monitoring solution exposes several ports that **MUST** be properly firewalled:
+- **Port 3000** (Grafana) - Contains sensitive database metrics and dashboards
+- **Port 58080** (PGWatch Postgres) - Database monitoring interface  
+- **Port 58089** (PGWatch Prometheus) - Database monitoring interface
+- **Port 59090** (Prometheus) - Metrics storage and queries
+- **Port 59091** (PGWatch Prometheus endpoint) - Metrics collection
+- **Port 55000** (Flask API) - Backend API service
+- **Port 55432** (Demo DB) - When using `--demo` option
+- **Port 55433** (Metrics DB) - PostgreSQL metrics storage
+
+**Configure your firewall to:**
+- Block public access to all monitoring ports
+- Allow access only from trusted networks/IPs
+- Use VPN or SSH tunnels for remote access
+
+Failure to secure these ports may expose sensitive database information!
+
 ## 🚀 Quick start
 
 Create a new DB user in database to be monitored (skip this if you want just to check out `postgres_ai` monitoring with a synthetic `demo` database):

postgres_ai

@@ -200,16 +200,28 @@ check_docker_running() {
     log_info "Checking Docker daemon status..."
 
     if ! docker info &> /dev/null; then
-        log_error "Docker daemon is not running"
+        log_error "Cannot access Docker daemon"
         echo
-        echo "Please start Docker:"
-        echo "  macOS: Start Docker Desktop application"
-        echo "  Linux: sudo systemctl start docker"
-        echo "  Windows: Start Docker Desktop application"
+        echo "This could be due to:"
+        echo "  1. Docker daemon not running"
+        echo "  2. User lacks permission to access Docker"
+        echo
+        echo "Solutions:"
+        echo "  If Docker daemon is not running:"
+        echo "    • macOS: Start Docker Desktop application"
+        echo "    • Linux: sudo systemctl start docker"
+        echo "    • Windows: Start Docker Desktop application"
+        echo
+        echo "  If permission denied:"
+        echo "    • Linux: Add user to docker group: sudo usermod -aG docker \$USER"
+        echo "    • Then log out and back in, or run: newgrp docker"
+        echo "    • Verify with: docker run hello-world"
+        echo
+        echo "  Alternative: Run postgres_ai with sudo (not recommended)"
         exit 1
     fi
 
-    log_success "Docker daemon is running"
+    log_success "Docker daemon is accessible"
 }
 
 # Check system resources