Send metrics for the running postgresql service (staic only) (#139)

Author: iAziz786

app/jobs/metricsjob/metricsjob.go

@@ -0,0 +1,94 @@
+// Package metricsjob
+package metricsjob
+
+import (
+	"context"
+	"hostlink/app/services/metrics"
+	"hostlink/domain/credential"
+	"sync"
+)
+
+type TriggerFunc func(context.Context, func() error)
+
+type MetricsJobConfig struct {
+	Trigger TriggerFunc
+	// CredFetchInterval tells in what intervals to call the cred fetch API
+	// When set to 0, it will call one and never calls it again
+	CredFetchInterval int
+}
+
+type MetricsJob struct {
+	config MetricsJobConfig
+	cancel context.CancelFunc
+	wg     sync.WaitGroup
+}
+
+func New() MetricsJob {
+	return NewJobWithConf(MetricsJobConfig{
+		Trigger:           Trigger,
+		CredFetchInterval: 2,
+	})
+}
+
+func NewJobWithConf(cfg MetricsJobConfig) MetricsJob {
+	if cfg.Trigger == nil {
+		cfg.Trigger = Trigger
+	}
+
+	return MetricsJob{
+		config: cfg,
+	}
+}
+
+func (mj *MetricsJob) Register(ctx context.Context, mp metrics.Pusher, mcred metrics.AuthGetter) context.CancelFunc {
+	ctx, cancel := context.WithCancel(ctx)
+	mj.cancel = cancel
+	var creds []credential.Credential
+	var beatCount int
+	mj.wg.Add(1)
+	go func() {
+		defer mj.wg.Done()
+		mj.config.Trigger(ctx, func() (err error) {
+			beatCount++
+
+			// Determine if we should fetch credentials this beat
+			shouldFetch := len(creds) == 0 ||
+				(mj.config.CredFetchInterval > 0 && beatCount%mj.config.CredFetchInterval == 0)
+
+			if shouldFetch {
+				creds, err = mcred.GetCreds()
+				if err != nil {
+					return err
+				}
+
+				if len(creds) == 0 {
+					// no op, waiting for the creds to be available
+					return nil
+				}
+
+				var pgcred credential.Credential
+				for _, cred := range creds {
+					// only support one db for now, first match will exit the finding of creds
+					if cred.Dialect == "postgresql" {
+						pgcred = cred
+						break
+					}
+				}
+
+				// Only push when we actually fetch credentials
+				return mp.Push(pgcred)
+			}
+
+			// If we didn't fetch this beat, return nil (no push)
+			return nil
+		})
+	}()
+	return cancel
+}
+
+func (mj *MetricsJob) Shutdown() {
+	if mj.cancel != nil {
+		mj.cancel()
+	}
+	mj.wg.Wait()
+}