doc: monitord package documentation (#77)

Author: RawanMostafa08

docs/internals/monitord/readme.md

@@ -0,0 +1,58 @@
+# Monitord Package
+
+## Introduction
+
+monitord package is responsible for continuously monitoring a node’s system resources.
+It provides a monitor stream for components such as CPU, memory, disk, network cards, and system uptime.
+
+
+## Interface
+### System Monitor
+
+```go
+// systemMonitor implements the pkg.SystemMonitor interface
+type systemMonitor struct {
+    duration time.Duration // duration between statistics collection
+    node     uint32        // node ID
+    cl       zbus.Client   // client used to request node data
+}
+
+type SystemMonitor interface {
+
+// CPU starts cpu monitor stream
+// It periodically emits CPU usage percentage and time statistics
+CPU(ctx context.Context) <-chan pkg.TimesStat
+
+// Disks starts disk monitor stream
+// It periodically emits disk stats for all mounted disks, including number of read/write operations, IO time, serial number
+Disks(ctx context.Context) <-chan pkg.DisksIOCountersStat
+
+// Get the types of workloads can be deployed depending on the network manager running on the node
+GetNodeFeatures() []pkg.NodeFeature
+
+// Memory starts memory monitor stream
+// It periodically emits VirtualMemoryStat containing memory usage statistics like Total, Available and Used in bytes
+Memory(ctx context.Context) <-chan pkg.VirtualMemoryStat
+
+// Nics starts Nic monitor stream
+// It periodically emits Nic stats for all available network cards, including number of packets sent, received or dropped
+Nics(ctx context.Context) <-chan pkg.NicsIOCounterStat
+
+// Returns node ID
+NodeID() uint32
+}
+```
+
+### Host Monitor
+
+```go
+// hostMonitor provides host-level monitoring such as system uptime.
+type hostMonitor struct {
+	duration time.Duration
+}
+
+type HostMonitor interface {
+    // Uptime periodically reads /proc/uptime file, parses it and emits the uptime
+	Uptime(ctx context.Context) <-chan time.Duration
+}
+```