/*
Copyright 2018 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package metrics

import (
	"github.com/prometheus/client_golang/prometheus"
	"sigs.k8s.io/controller-runtime/pkg/metrics"
)

var (
	// ReconcileTotal is a prometheus counter metrics which holds the total
	// number of reconciliations per controller. It has two labels. controller label refers
	// to the controller name and result label refers to the reconcile result i.e
	// success, error, requeue, requeue_after
	ReconcileTotal = prometheus.NewCounterVec(prometheus.CounterOpts{
		Name: "controller_runtime_reconcile_total",
		Help: "Total number of reconciliations per controller",
	}, []string{"controller", "result"})

	// ReconcileErrors is a prometheus counter metrics which holds the total
	// number of errors from the Reconciler
	ReconcileErrors = prometheus.NewCounterVec(prometheus.CounterOpts{
		Name: "controller_runtime_reconcile_errors_total",
		Help: "Total number of reconciliation errors per controller",
	}, []string{"controller"})

	// ReconcileTime is a prometheus metric which keeps track of the duration
	// of reconciliations
	ReconcileTime = prometheus.NewHistogramVec(prometheus.HistogramOpts{
		Name: "controller_runtime_reconcile_time_seconds",
		Help: "Length of time per reconciliation per controller",
		Buckets: []float64{0.005, 0.01, 0.025, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
			1.25, 1.5, 1.75, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 60},
	}, []string{"controller"})

	// WorkerCount is a prometheus metric which holds the number of
	// concurrent reconciles per controller
	WorkerCount = prometheus.NewGaugeVec(prometheus.GaugeOpts{
		Name: "controller_runtime_max_concurrent_reconciles",
		Help: "Maximum number of concurrent reconciles per controller",
	}, []string{"controller"})

	// ActiveWorkers is a prometheus metric which holds the number
	// of active workers per controller
	ActiveWorkers = prometheus.NewGaugeVec(prometheus.GaugeOpts{
		Name: "controller_runtime_active_workers",
		Help: "Number of currently used workers per controller",
	}, []string{"controller"})
)

func init() {
	metrics.Registry.MustRegister(
		ReconcileTotal,
		ReconcileErrors,
		ReconcileTime,
		WorkerCount,
		ActiveWorkers,
		// expose process metrics like CPU, Memory, file descriptor usage etc.
		prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}),
		// expose Go runtime metrics like GC stats, memory stats etc.
		prometheus.NewGoCollector(),
	)
}
