GRA-1298: License check changes, free tier limits for saas (#2418)

* set free tier limits through config

* add host limit to config

* check for host limit on free tier

* fix license validation, replace node limit with hosts

* add hosts to telemetry data

* debug init

* validate license every 1hr

* hook manager, api to fetch server usage

* hook manager, server usage api

* encode json server usage api

* update ngork url

* update license validation endpoint

* avoid setting limits on eer

* adding hotfix

* correct users limits env var

* add comments to exported funcs

---------

Co-authored-by: afeiszli <alex.feiszli@gmail.com>

logic/timer.go

@@ -1,10 +1,13 @@
 package logic
 
 import (
+	"context"
 	"fmt"
+	"sync"
 	"time"
 
 	"github.com/gravitl/netmaker/logger"
+	"github.com/gravitl/netmaker/models"
 )
 
 // == Constants ==
@@ -12,6 +15,9 @@ import (
 // How long to wait before sending telemetry to server (24 hours)
 const timer_hours_between_runs = 24
 
+// HookManagerCh - channel to add any new hooks
+var HookManagerCh = make(chan models.HookDetails, 2)
+
 // == Public ==
 
 // TimerCheckpoint - Checks if 24 hours has passed since telemetry was last sent. If so, sends telemetry data to posthog
@@ -40,6 +46,36 @@ func AddHook(ifaceToAdd interface{}) {
 	timeHooks = append(timeHooks, ifaceToAdd)
 }
 
+// StartHookManager - listens on `HookManagerCh` to run any hook
+func StartHookManager(ctx context.Context, wg *sync.WaitGroup) {
+	defer wg.Done()
+	for {
+		select {
+		case <-ctx.Done():
+			logger.Log(0, "## Stopping Hook Manager")
+			return
+		case newhook := <-HookManagerCh:
+			wg.Add(1)
+			go addHookWithInterval(ctx, wg, newhook.Hook, newhook.Interval)
+		}
+	}
+}
+
+func addHookWithInterval(ctx context.Context, wg *sync.WaitGroup, hook func() error, interval time.Duration) {
+	defer wg.Done()
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			hook()
+		}
+	}
+
+}
+
 // == private ==
 
 // timeHooks - functions to run once a day, functions must take no parameters