Prometheus vs Splunk: What are the differences?

Prometheus and Splunk are both popular tools used for monitoring and troubleshooting in the field of DevOps. Let's explore the key differences between them.

1. Data Collection and Storage: Prometheus is an open-source solution that uses a pull model for data collection. It gathers metrics by scraping designated endpoints at predefined intervals. The collected data is then stored in a time-series database. On the other hand, Splunk is a commercial solution that uses a push model. It receives data from various sources and indexes it in a centralized repository for easier search and analysis.

2. Network Overhead: Prometheus requires a relatively low network overhead as it only pulls data from the endpoints when needed. However, Splunk has a higher network overhead as it continuously receives data from multiple sources and requires more bandwidth for real-time monitoring.

3. Query Language and Analytics: Prometheus offers a flexible and powerful query language called PromQL, which allows users to perform complex queries and aggregations on the collected metrics. Splunk, on the other hand, uses its own search processing language (SPL), which provides a wide range of features for data search, correlation, and visualization.

4. Scalability: Prometheus is designed to be highly scalable, allowing it to handle large volumes of data and thousands of endpoints. It can easily be horizontally scaled by adding more instances. Splunk, on the other hand, may require additional infrastructure to scale effectively. It is more suitable for smaller or medium-scale deployments.

5. Alerting and Monitoring: Prometheus has built-in alerting capabilities, allowing users to define and configure alerts based on custom thresholds and conditions. It can send notifications through various channels such as email, Slack, or PagerDuty. Splunk also provides alerting capabilities, but it requires additional configuration and setup.

6. Cost: Prometheus is free and open-source, making it a cost-effective solution for many organizations. Splunk, being a commercial product, comes with associated licensing costs, which can be quite substantial depending on the deployment size and features used.

In summary, Prometheus is an open-source solution with powerful querying capabilities, lower network overhead, and cost-effectiveness. In contrast, Splunk is a commercial solution that offers advanced features, better scalability, and more options for data collection.