Nagios vs Prometheus vs Sensu: What are the differences?

<Write Introduction here>

1. Monitoring Protocol: Nagios primarily uses an active checking method where the Nagios server actively queries servers and devices at regular intervals to check their status. Prometheus, on the other hand, uses a pull method where the Prometheus server scrapes metrics from targeted endpoints at defined intervals. Sensu also employs a pull-based approach but allows for greater flexibility in terms of choosing the monitoring protocol.

2. Data Storage: Nagios stores monitoring data in flat text files, which can lead to performance issues when handling large amounts of data. Prometheus stores data in a time-series database, making it more efficient for querying and analyzing data. Sensu allows users to choose different storage backends, such as Redis or InfluxDB, providing more flexibility in data storage.

3. Scalability: Nagios can become difficult to scale horizontally due to its architecture, which may require additional effort to set up a distributed monitoring system. Prometheus is designed to be highly scalable and can effortlessly handle large-scale deployments and high-volume data collection. Sensu also offers good scalability, making it easier to manage and monitor various resources in a distributed environment.

4. Alerting and Notification: Nagios provides basic alerting and notification features through email and SMS notifications. Prometheus includes a robust alerting manager that can send alerts via various channels like email, Slack, and PagerDuty, making it more versatile in notifying users of issues. Sensu also offers advanced alerting capabilities, allowing users to define complex alerting rules and integrate with multiple notification channels.

5. Metrics Monitoring: Nagios is more focused on monitoring the status of various services and hosts, providing basic metrics. Prometheus specializes in metrics monitoring, offering extensive support for collecting, storing, and querying metrics from different endpoints. Sensu, like Prometheus, emphasizes metrics monitoring, allowing for detailed analysis and visualization of performance data across the infrastructure.

6. Community and Support: Nagios has a large and established user community, providing extensive documentation and resources for troubleshooting and customization. Prometheus has also gained significant traction in the monitoring community, with active development and a growing user base. Sensu, though newer compared to Nagios and Prometheus, has a strong community backing and offers responsive support for users in need.

In Summary, Nagios, Prometheus, and Sensu differ in terms of monitoring protocol, data storage, scalability, alerting capabilities, metrics monitoring, and community support.