What is Prometheus?
Prometheus is an open-source system that collects, stores, and lets you query metrics (numbers) from software applications and infrastructure. It helps you see how things are performing over time.
Let's break it down
- Open-source: Free to use and anyone can look at or change the code.
- System: A set of tools that work together.
- Collects metrics: Gathers numbers like CPU usage, request latency, or error counts.
- Stores: Saves those numbers in a time-ordered database.
- Query: Lets you ask questions about the data, like “what was the average response time last hour?”.
- Software applications and infrastructure: Anything running on servers, containers, or cloud services.
Why does it matter?
Knowing the health and performance of your services lets you spot problems early, keep users happy, and make informed decisions about scaling or fixing issues. Prometheus gives you that visibility in a simple, automated way.
Where is it used?
- Monitoring micro-service architectures in Kubernetes clusters.
- Tracking performance of web applications and APIs.
- Observing hardware resources (CPU, memory, disk) on virtual machines.
- Alerting on abnormal behavior, such as sudden spikes in error rates.
Good things about it
- Easy to set up with built-in exporters for many common services.
- Powerful query language (PromQL) for flexible data analysis.
- Scales well for large numbers of metrics and high write rates.
- Integrates with alerting tools (Alertmanager) and visualization dashboards (Grafana).
- Strong community and extensive documentation.
Not-so-good things
- Limited long-term storage; raw data is usually kept for weeks unless external solutions are added.
- Learning curve for PromQL can be steep for beginners.
- Requires careful planning of metric naming and labeling to avoid chaos.
- Not ideal for logging or tracing; it focuses only on numeric metrics.