#!/bin/bash

# Variables
NODE_EXPORTER_VERSION="1.0.1"
NODE_EXPORTER_TAR="node_exporter-${NODE_EXPORTER_VERSION}.linux-amd64.tar.gz"
NODE_EXPORTER_DIR="node_exporter-${NODE_EXPORTER_VERSION}.linux-amd64"
DOWNLOAD_URL="https://github.com/prometheus/node_exporter/releases/download/v${NODE_EXPORTER_VERSION}/${NODE_EXPORTER_TAR}"
SERVICE_FILE="/usr/lib/systemd/system/node_exporter.service"
USER="node_exporter"

# Download Node Exporter
wget $DOWNLOAD_URL

# Create User and Directories
sudo groupadd -f $USER
sudo useradd -g $USER --no-create-home --shell /bin/false $USER
sudo mkdir /etc/node_exporter
sudo chown $USER:$USER /etc/node_exporter

# Unpack Node Exporter Binary
tar -xvf $NODE_EXPORTER_TAR
mv $NODE_EXPORTER_DIR node_exporter-files

# Install Node Exporter
sudo cp node_exporter-files/node_exporter /usr/bin/
sudo chown $USER:$USER /usr/bin/node_exporter

# Setup Node Exporter Service
sudo bash -c "cat > $SERVICE_FILE" <<EOL
[Unit]
Description=Node Exporter
Documentation=https://prometheus.io/docs/guides/node-exporter/
Wants=network-online.target
After=network-online.target

[Service]
User=$USER
Group=$USER
Type=simple
Restart=on-failure
ExecStart=/usr/bin/node_exporter --web.listen-address=:9138

[Install]
WantedBy=multi-user.target
EOL

sudo chmod 664 $SERVICE_FILE

# Reload systemd and Start Node Exporter
sudo systemctl daemon-reload
sudo systemctl start node_exporter
sudo systemctl status node_exporter

# Configure node_exporter to start at boot
sudo systemctl enable node_exporter.service

# If firewalld is enabled and running, add a rule for port 9200
# sudo firewall-cmd --permanent --zone=public --add-port=9200/tcp
# sudo firewall-cmd --reload

# Clean Up
rm -rf $NODE_EXPORTER_TAR node_exporter-files

echo "Node Exporter setup completed."