Prometheus

• The Prometheus monitoring system and time series database
• To monitor workloads
• open source monitoring solution
• Scape data/metrics using http end points
• All data is stored as TimeSeries
• Every time series is identified by metric name and a set of key-value pairs, called labels
• 
  
• Types of metrics
• Counter
• Value that only goes up
  
• Gauge
• Numeric value that can go up and down(like cpu load)
  
• Histogram
• Sample observations(request duration, response sizes)
  
• Summary
• PromQL
• Provides builtin operators and functions
• expressions over time-series vectors
• Querying metrics
• Instant Vector
• single sample for each time series - all sharing the same time stamp
• eg: node_cpu_seconds_total
  
• Range Vector
• range of data points over time for each time series
• eg: node_cpu_seconds_total[5min]
• Scalar
• Simple numeric floating point value
• Service discovery
• Automatic detection of devices and services offered by these devices on a computer network
• Exporters
• Export third party metrics  to Prometheus metrics

Alerting

• Alerting rules
• Rules live in Prometheus server config
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• Alert manager