📈 Aralez Prometheus Metrics Reference

This document outlines Prometheus metrics for the Aralez reverse proxy. These metrics can be used for monitoring, alerting and performance analysis.

Exposed to http://config_address/metrics

By default http://127.0.0.1:3000/metrics

📊 Example Grafana dashboard during stress test :

Aralez

🛠️ Prometheus Metrics

1. aralez_requests_total

  • Type: Counter
  • Purpose: Total amount requests served by Aralez.

PromQL example:

rate(aralez_requests_total[5m])

2. aralez_errors_total

  • Type: Counter
  • Purpose: Count of requests that resulted in an error.

PromQL example:

rate(aralez_errors_total[5m])

3. aralez_responses_total{status="200"}

  • Type: CounterVec
  • Purpose: Count of responses by HTTP status code.

PromQL example:

rate(aralez_responses_total{status=~"5.."}[5m]) > 0

Useful for alerting on 5xx errors.

4. aralez_response_latency_seconds

  • Type: Histogram
  • Purpose: Tracks the latency of responses in seconds.

Example bucket output:

aralez_response_latency_seconds_bucket{le="0.01"}  15
aralez_response_latency_seconds_bucket{le="0.1"}   120
aralez_response_latency_seconds_bucket{le="0.25"}  245
aralez_response_latency_seconds_bucket{le="0.5"}   500
...
aralez_response_latency_seconds_count  1023
aralez_response_latency_seconds_sum    42.6
Metric Meaning
bucket{le="0.1"} 120 120 requests were ≤ 100ms
bucket{le="0.25"} 245 245 requests were ≤ 250ms
count Total number of observations (i.e., total responses measured)
sum Total time of all responses, in seconds

🔍 How to interpret:

  • le means “less than or equal to”.
  • count is total amount of observations.
  • sum is the total time (in seconds) of all responses.

PromQL examples:

🔹 95th percentile latency

histogram_quantile(0.95, rate(aralez_response_latency_seconds_bucket[5m]))

🔹 Average latency

rate(aralez_response_latency_seconds_sum[5m]) / rate(aralez_response_latency_seconds_count[5m])

✅ Notes

  • Metrics are registered after the first served request.

✅ Summary of key metrics

Metric Name Type What it Tells You
aralez_requests_total Counter Total requests served
aralez_errors_total Counter Number of failed requests
aralez_responses_total{status="200"} CounterVec Response status breakdown
aralez_response_latency_seconds Histogram How fast responses are