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Add slab metrics #1071

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10075fe
Add slab metrics in nginx plus collector
gudvyach May 23, 2025
f9ec412
Add slab metrics description to README
gudvyach May 23, 2025
1c93cd9
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] May 23, 2025
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12 changes: 12 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@ NGINX Prometheus exporter makes it possible to monitor NGINX or NGINX Plus using
- [Stream Connections Limiting](#stream-connections-limiting)
- [Cache](#cache)
- [Worker](#worker)
- [Slabs](#slabs)
- [Troubleshooting](#troubleshooting)
- [Releases](#releases)
- [Docker images](#docker-images)
Expand Down Expand Up @@ -432,6 +433,17 @@ Flags:
| `nginxplus_worker_http_requests_total` | Counter | The total number of client requests received | `id`, `pid` |
| `nginxplus_worker_http_requests_current` | Gauge | The current number of client requests that are currently being processed | `id`, `pid` |

### [Slabs](https://nginx.org/en/docs/http/ngx_http_api_module.html#slabs_)

| Name | Type | Description | Labels |
| ---------------------------------------- | ------- | ------------------------------------------------------------------------------- | -------------- |
| `nginxplus_slab_fails` | Gauge | Total number of unsuccessful attempts to allocate memory of specified size | `slot`, `zone` |
| `nginxplus_slab_reqs` | Gauge | Total number of attempts to allocate memory of specified size | `slot`, `zone` |
| `nginxplus_slab_free` | Gauge | Current number of free memory slots | `slot`, `zone` |
| `nginxplus_slab_used` | Gauge | Current number of used memory slots | `slot`, `zone` |
| `nginxplus_slab_pages_free` | Gauge | Current number of free memory pages | `zone` |
| `nginxplus_slab_pages_used` | Gauge | Current number of used memory pages | `zone` |

Connect to the `/metrics` page of the running exporter to see the complete list of metrics along with their
descriptions. Note: to see server zones related metrics you must configure [status
zones](https://nginx.org/en/docs/http/ngx_http_api_module.html#status_zone) and to see upstream related metrics you
Expand Down
32 changes: 32 additions & 0 deletions collector/nginx_plus.go
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Expand Up @@ -35,6 +35,7 @@ type NginxPlusCollector struct {
logger *slog.Logger
cacheZoneMetrics map[string]*prometheus.Desc
workerMetrics map[string]*prometheus.Desc
slabsMetrics map[string]*prometheus.Desc
nginxClient *plusclient.NginxClient
streamServerZoneMetrics map[string]*prometheus.Desc
streamZoneSyncMetrics map[string]*prometheus.Desc
Expand Down Expand Up @@ -563,6 +564,14 @@ func NewNginxPlusCollector(nginxClient *plusclient.NginxClient, namespace string
"http_requests_total": newWorkerMetric(namespace, "http_requests_total", "The total number of client requests received by the worker process", constLabels),
"http_requests_current": newWorkerMetric(namespace, "http_requests_current", "The current number of client requests that are currently being processed by the worker process", constLabels),
},
slabsMetrics: map[string]*prometheus.Desc{
"pages_used": newSlabPagesMetric(namespace, "pages_used", "Current number of used memory pages", constLabels),
"pages_free": newSlabPagesMetric(namespace, "pages_free", "Current number of free memory pages", constLabels),
"slots_free": newSlabMetric(namespace, "free", "Current number of free memory slots", constLabels),
"slots_used": newSlabMetric(namespace, "used", "Current number of used memory slots", constLabels),
"slots_reqs": newSlabMetric(namespace, "reqs", "Total number of attempts to allocate memory of specified size", constLabels),
"slots_fails": newSlabMetric(namespace, "fails", "Total number of unsuccessful attempts to allocate memory of specified size", constLabels),
},
}
}

Expand Down Expand Up @@ -616,6 +625,9 @@ func (c *NginxPlusCollector) Describe(ch chan<- *prometheus.Desc) {
for _, m := range c.workerMetrics {
ch <- m
}
for _, m := range c.slabsMetrics {
ch <- m
}
}

// Collect fetches metrics from NGINX Plus and sends them to the provided channel.
Expand Down Expand Up @@ -1246,6 +1258,18 @@ func (c *NginxPlusCollector) Collect(ch chan<- prometheus.Metric) {
ch <- prometheus.MustNewConstMetric(c.workerMetrics["http_requests_total"], prometheus.CounterValue, float64(worker.HTTP.HTTPRequests.Total), workerID, workerPID)
ch <- prometheus.MustNewConstMetric(c.workerMetrics["http_requests_current"], prometheus.GaugeValue, float64(worker.HTTP.HTTPRequests.Current), workerID, workerPID)
}

for name, slab := range stats.Slabs {
ch <- prometheus.MustNewConstMetric(c.slabsMetrics["pages_used"], prometheus.GaugeValue, float64(slab.Pages.Used), name)
ch <- prometheus.MustNewConstMetric(c.slabsMetrics["pages_free"], prometheus.GaugeValue, float64(slab.Pages.Free), name)

for memory, slot := range slab.Slots {
ch <- prometheus.MustNewConstMetric(c.slabsMetrics["slots_free"], prometheus.GaugeValue, float64(slot.Free), name, memory)
ch <- prometheus.MustNewConstMetric(c.slabsMetrics["slots_used"], prometheus.GaugeValue, float64(slot.Used), name, memory)
ch <- prometheus.MustNewConstMetric(c.slabsMetrics["slots_reqs"], prometheus.GaugeValue, float64(slot.Reqs), name, memory)
ch <- prometheus.MustNewConstMetric(c.slabsMetrics["slots_fails"], prometheus.GaugeValue, float64(slot.Fails), name, memory)
}
}
}

var upstreamServerStates = map[string]float64{
Expand Down Expand Up @@ -1331,3 +1355,11 @@ func newCacheZoneMetric(namespace string, metricName string, docString string, v
func newWorkerMetric(namespace string, metricName string, docString string, constLabels prometheus.Labels) *prometheus.Desc {
return prometheus.NewDesc(prometheus.BuildFQName(namespace, "worker", metricName), docString, []string{"id", "pid"}, constLabels)
}

func newSlabPagesMetric(namespace string, metricName string, docString string, constLabels prometheus.Labels) *prometheus.Desc {
return prometheus.NewDesc(prometheus.BuildFQName(namespace, "slab", metricName), docString, []string{"zone"}, constLabels)
}

func newSlabMetric(namespace string, metricName string, docString string, constLabels prometheus.Labels) *prometheus.Desc {
return prometheus.NewDesc(prometheus.BuildFQName(namespace, "slab", metricName), docString, []string{"zone", "slot"}, constLabels)
}