Prometheus: Add TLS encryption to Prometheus Node Exporter

This documentation is part of the Retrieving metrics from Linux guide. View the full guide here: How to retrieve Linux server metrics in Prometheus using Node Exporter.

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By default, Node Exporter does not encrypt communications. This means that credentials, including the previously defined password, are transmitted in plain text. To secure communications, you can enable TLS encryption as follows.

Creating TLS certificates

Run the following commands to create a TLS certificate and key:

# Create TLS certificate
cd /tmp
sudo openssl req -new -newkey rsa:2048 -days 3650 -nodes -x509 \
  -keyout /etc/prometheus_node_exporter/tlsCertificate.key \
  -out /etc/prometheus_node_exporter/tlsCertificate.crt \
  -subj "/CN=`hostname`" \
  -addext "subjectAltName = DNS:`hostname`"
sudo chmod 600 /etc/prometheus_node_exporter/*
sudo chown -R node_exporter:node_exporter /etc/prometheus_node_exporter

Updating the configuration

Append the following lines to the configuration file to add TLS settings and then restart Node Exporter:

sudo cat << 'EOF' >> /etc/prometheus_node_exporter/configuration.yml
tls_server_config:
  cert_file: /etc/prometheus_node_exporter/tlsCertificate.crt
  key_file: /etc/prometheus_node_exporter/tlsCertificate.key

EOF

# Restart Prometheus Node Exporter
sudo systemctl restart node_exporter

You can verify that TLS is active by connecting via HTTPS with the following command:

curl -k -u prometheus:${password} https://localhost:9100/metrics

Note that this method does not use a CA certificate, so you need to pass the "-k" option to cURL to bypass certificate verification.