Add new metrics docs

Author: DarthSim

docs/monitoring/cloud_watch.mdx

@@ -13,9 +13,10 @@ imgproxy can send its metrics to Amazon CloudWatch. To use this feature, do the
 
 imgproxy sends the following metrics to CloudWatch:
 
+* `Workers`: the configured number of imgproxy workers
 * `RequestsInProgress`: the number of requests currently in progress
 * `ImagesInProgress`: the number of images currently in progress
-* `WorkersUtilization`, `ConcurrencyUtilization`: the percentage of imgproxy's workers utilization. Calculated as `RequestsInProgress / IMGPROXY_WORKERS * 100`
+* `WorkersUtilization`, `ConcurrencyUtilization`: the percentage of imgproxy's workers utilization. Calculated as `RequestsInProgress / Workers * 100`
 * `BufferSize`: a summary of the download buffers sizes (in bytes)
 * `BufferDefaultSize`: calibrated default buffer size (in bytes)
 * `BufferMaxSize`: calibrated maximum buffer size (in bytes)

docs/monitoring/datadog.mdx

@@ -36,8 +36,10 @@ imgproxy will send the following info to Datadog:
 
 When the `IMGPROXY_DATADOG_ENABLE_ADDITIONAL_METRICS` environment variable is set to `true`, imgproxy will send the following additional metrics to Datadog:
 
+* `imgproxy.workers`: the configured number of imgproxy workers
 * `imgproxy.requests_in_progress`: the number of requests currently in progress
 * `imgproxy.images_in_progress`: the number of images currently in progress
+* `imgproxy.workers_utilization`: the percentage of imgproxy's workers utilization. Calculated as `imgproxy.requests_in_progress / imgproxy.workers * 100`
 * `imgproxy.buffer.size`: a histogram of the download buffers sizes (in bytes)
 * `imgproxy.buffer.default_size`: calibrated default buffer size (in bytes)
 * `imgproxy.buffer.max_size`: calibrated maximum buffer size (in bytes)

docs/monitoring/new_relic.mdx

@@ -22,8 +22,10 @@ imgproxy will send the following info to New Relic:
 
 Additionally, imgproxy sends the following metrics over [Metrics API](https://docs.newrelic.com/docs/data-apis/ingest-apis/metric-api/introduction-metric-api/):
 
+* `imgproxy.workers`: the configured number of imgproxy workers
 * `imgproxy.requests_in_progress`: the number of requests currently in progress
 * `imgproxy.images_in_progress`: the number of images currently in progress
+* `imgproxy.workers_utilization`: the percentage of imgproxy's workers utilization. Calculated as `imgproxy.requests_in_progress / imgproxy.workers * 100`
 * `imgproxy.buffer.size`: a summary of the download buffers sizes (in bytes)
 * `imgproxy.buffer.default_size`: calibrated default buffer size (in bytes)
 * `imgproxy.buffer.max_size`: calibrated maximum buffer size (in bytes)

docs/monitoring/open_telemetry.mdx

@@ -50,8 +50,10 @@ imgproxy will send the following info to the collector:
 
 If `IMGPROXY_OPEN_TELEMETRY_ENABLE_METRICS` is set to `true`, imgproxy will also send the following metrics to the collector:
 
+* `workers`: the configured number of imgproxy workers
 * `requests_in_progress`: the number of requests currently in progress
 * `images_in_progress`: the number of images currently in progress
+* `workers_utilization`: the percentage of imgproxy's workers utilization. Calculated as `requests_in_progress / workers * 100`
 * `buffer_size_bytes`: a histogram of buffer sizes (in bytes)
 * `buffer_default_size_bytes`: calibrated default buffer size (in bytes)
 * `buffer_max_size_bytes`: calibrated maximum buffer size (in bytes)

docs/monitoring/prometheus.mdx

@@ -17,8 +17,10 @@ imgproxy will collect the following metrics:
 * `errors_total`: a counter of the occurred errors separated by type (timeout, downloading, processing)
 * `request_duration_seconds`: a histogram of the request latency (in seconds)
 * `request_span_duration_seconds`: a histogram of the request latency (in seconds) separated by span (queue, downloading, processing)
+* `workers`: the configured number of imgproxy workers
 * `requests_in_progress`: the number of requests currently in progress
 * `images_in_progress`: the number of images currently in progress
+* `workers_utilization`: the percentage of imgproxy's workers utilization. Calculated as `requests_in_progress / workers * 100`
 * `buffer_size_bytes`: a histogram of the download buffers sizes (in bytes)
 * `buffer_default_size_bytes`: calibrated default buffer size (in bytes)
 * `buffer_max_size_bytes`: calibrated maximum buffer size (in bytes)