Add Crossplane Metrics Documentation

content/master/concepts/_index.md

@@ -78,3 +78,6 @@ building and managing external resources through Kubernetes.
 * [**Packages**]({{<ref "./packages">}}) are a convenient way to package up an
   entire custom platform and define any other Crossplane related requirements.
   Packages define how to install Providers, custom APIs or composition functions.
+
+* [**Metrics**]({{<ref "./metrics">}}) are essential for monitoring Crossplane's 
+  operations, helping to identify and resolve potential issues.

content/master/concepts/metrics.md

@@ -0,0 +1,44 @@
+---
+title: Metrics
+weight: 60
+description: "Metrics are essential for monitoring Crossplane's operations, helping to quickly identify and resolve potential issues."
+---
+
+This page offers explanations of various metrics gathered from Crossplane, which are essential for effective monitoring and alerting in your Crossplane environment. 
+Understanding these metrics help you maintain the health and performance of your resources, ensuring that any issues can be identified and addressed. 
+Please note that this document focuses on Crossplane specific metrics and doesn't cover standard Go metrics.
+
+
+{{<table "table table-sm">}}
+| Metric Name | Description | Further Explanation |
+| --- | --- | --- |
+| {{<hover label="certwatcher_read_certificate_errors_total" line="1">}}certwatcher_read_certificate_errors_total{{</hover>}} | Total number of certificate read errors |  |
+| {{<hover label="certwatcher_read_certificate_total" line="2">}}certwatcher_read_certificate_total{{</hover>}} | Total number of certificate reads |  |
+| {{<hover label="composition_run_function_seconds_bucket" line="3">}}composition_run_function_seconds_bucket{{</hover>}} | Histogram of RunFunctionResponse latency (seconds) |  |
+| {{<hover label="controller_runtime_active_workers" line="4">}}controller_runtime_active_workers{{</hover>}} | Number of used workers per controller | The number of threads that currently process jobs from the work queue. |
+| {{<hover label="controller_runtime_max_concurrent_reconciles" line="5">}}controller_runtime_max_concurrent_reconciles{{</hover>}} | Maximum number of concurrent reconciles per controller | Describes how reconciles can happen in parallel. |
+| {{<hover label="controller_runtime_reconcile_errors_total" line="6">}}controller_runtime_reconcile_errors_total{{</hover>}} | Total number of reconciliation errors per controller | A counter that counts reconcile errors. Sharp or non stop rising of this metric might be a problem. |
+| {{<hover label="controller_runtime_reconcile_time_seconds_bucket" line="7">}}controller_runtime_reconcile_time_seconds_bucket{{</hover>}} | Length of time per reconciliation per controller |  |
+| {{<hover label="controller_runtime_reconcile_total" line="8">}}controller_runtime_reconcile_total{{</hover>}} | Total number of reconciliations per controller |  |
+| {{<hover label="controller_runtime_webhook_latency_seconds_bucket" line="9">}}controller_runtime_webhook_latency_seconds_bucket{{</hover>}} | Histogram of the latency of processing admission requests |  |
+| {{<hover label="controller_runtime_webhook_requests_in_flight" line="10">}}controller_runtime_webhook_requests_in_flight{{</hover>}} | Current number of admission requests served |  |
+| {{<hover label="controller_runtime_webhook_requests_total" line="11">}}controller_runtime_webhook_requests_total{{</hover>}} | Total number of admission requests by HTTP status code |  |
+| {{<hover label="rest_client_requests_total" line="12">}}rest_client_requests_total{{</hover>}} | Number of HTTP requests, partitioned by status code, method, and host |  |
+| {{<hover label="workqueue_adds_total" line="13">}}workqueue_adds_total{{</hover>}} | Total number of adds handled by `workqueue` |  |
+| {{<hover label="workqueue_depth" line="14">}}workqueue_depth{{</hover>}} | Current depth of `workqueue` |  |
+| {{<hover label="workqueue_longest_running_processor_seconds" line="15">}}workqueue_longest_running_processor_seconds{{</hover>}} | How many seconds has the longest running processor for `workqueue` been running |  |
+| {{<hover label="workqueue_queue_duration_seconds_bucket" line="16">}}workqueue_queue_duration_seconds_bucket{{</hover>}} | How long in seconds an item stays in `workqueue` before requested | The time it takes from the moment a job enter the `workqueue` until the processing of this job starts. |
+| {{<hover label="workqueue_retries_total" line="17">}}workqueue_retries_total{{</hover>}} | Total number of retries handled by `workqueue` |  |
+| {{<hover label="workqueue_unfinished_work_seconds" line="18">}}workqueue_unfinished_work_seconds{{</hover>}} | The number of seconds of work has been done that's in progress and hasn't observed by `work_duration`. Large values means stuck threads. |  |
+| {{<hover label="workqueue_work_duration_seconds_bucket" line="19">}}workqueue_work_duration_seconds_bucket{{</hover>}} | How long in seconds processing an item from `workqueue` takes | The time it takes from the moment the job start until it finish (either successfully or with an error). |
+| {{<hover label="crossplane_managed_resource_exists" line="20">}}crossplane_managed_resource_exists{{</hover>}} | The number of managed resources that exist |  |
+| {{<hover label="crossplane_managed_resource_ready" line="21">}}crossplane_managed_resource_ready{{</hover>}} | The number of managed resources in `Ready=True` state |  |
+| {{<hover label="crossplane_managed_resource_synced" line="22">}}crossplane_managed_resource_synced{{</hover>}} | The number of managed resources in `Synced=True` state |  |
+| {{<hover label="upjet_resource_ext_api_duration_bucket" line="23">}}upjet_resource_ext_api_duration_bucket{{</hover>}} | Measures in seconds how long it takes a Cloud SDK call to complete |  |
+| {{<hover label="upjet_resource_external_api_calls_total" line="24">}}upjet_resource_external_api_calls_total{{</hover>}} | The number of external API calls | The number of calls to cloud providers, with labels describing the endpoints resources. |
+| {{<hover label="upjet_resource_reconcile_delay_seconds_bucket" line="25">}}upjet_resource_reconcile_delay_seconds_bucket{{</hover>}} | Measures in seconds how long the reconciles for a resource delay from the configured poll periods |  |
+| {{<hover label="crossplane_managed_resource_deletion_seconds_bucket" line="26">}}crossplane_managed_resource_deletion_seconds_bucket{{</hover>}} | The time it took to delete a managed resource |  |
+| {{<hover label="crossplane_managed_resource_first_time_to_readiness_seconds_bucket" line="27">}}crossplane_managed_resource_first_time_to_readiness_seconds_bucket{{</hover>}} | The time it took for a managed resource to become ready first time after creation |  |
+| {{<hover label="crossplane_managed_resource_first_time_to_reconcile_seconds_bucket" line="28">}}crossplane_managed_resource_first_time_to_reconcile_seconds_bucket{{</hover>}} | The time it took to detect a managed resource by the controller |  |
+| {{<hover label="upjet_resource_ttr_bucket" line="29">}}upjet_resource_ttr_bucket{{</hover>}} | Measures in seconds the `time-to-readiness` `(TTR)` for managed resources |  |
+{{< /table >}}