gRPC System Metrics — Telemetry Monitoring Microservice

A lightweight Telemetry Monitoring Microservice written in C++17 that collects real-time system metrics from a Linux machine and exposes them over gRPC.

graph LR;
  C[telemetry_client];
  S[telemetry_server];
  C -->|GetSystemMetrics| S;
  S -->|MetricsResponse| C;
  P[(Port 50051)];
  C -. gRPC .-> P;
  P -. gRPC .-> S;

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Features

Metric	Source
CPU usage %	/proc/stat (two-sample delta over 500 ms)
Memory usage %	/proc/meminfo (MemAvailable accounting)
Disk usage %	statvfs("/") — root filesystem

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Project Structure

grpc-system-metrics/
├── CMakeLists.txt               # Top-level CMake build definition
├── proto/
│   └── metrics.proto            # gRPC / Protobuf API contract
├── server/
│   └── telemetry_server.cpp     # gRPC server — collects & serves metrics
└── client/
    └── telemetry_client.cpp     # gRPC client — requests & displays metrics

Generated C++ bindings (metrics.pb.{cc,h} and metrics.grpc.pb.{cc,h}) are placed in <build-dir>/generated/ and never committed to source control.

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Prerequisites

Install the following on your Linux machine (Ubuntu/Debian instructions shown):

# Build tools
sudo apt update
sudo apt install -y build-essential cmake git

# Protocol Buffers compiler
sudo apt install -y protobuf-compiler libprotobuf-dev

# gRPC C++ library and the protoc plugin
sudo apt install -y libgrpc++-dev protobuf-compiler-grpc

Alternative (vcpkg):
If the apt packages are too old for your distro, build from source following the
gRPC Quick Start guide.

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Build

# 1. Clone / enter the project directory
cd grpc-system-metrics

# 2. Configure (Debug or Release)
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release

# 3. Compile
cmake --build build --parallel $(nproc)

Both executables appear in build/:

build/telemetry_server
build/telemetry_client

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Run

Start the server

./build/telemetry_server

Expected output:

[Server] Telemetry server listening on 0.0.0.0:50051
[Server] Press Ctrl+C to stop.

Run the client (in a second terminal)

./build/telemetry_client

Example output:

[Client] Connecting to localhost:50051 …

==================================================
        SYSTEM TELEMETRY REPORT
==================================================
 Timestamp  : 2026-03-11 14:22:09
--------------------------------------------------
 CPU Usage  :   4.20%  [#...................]
 Memory     :  61.83%  [############........]   (9893 / 16001 MiB)
 Disk (/)   :  38.50%  [#######.............]   (146 / 380 GiB)
==================================================

Connect to a remote server

./build/telemetry_client 192.168.1.10:50051

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How It Works

CPU Sampling (/proc/stat)

The kernel exposes cumulative tick counts since boot:

cpu  <user> <nice> <system> <idle> <iowait> <irq> <softirq> <steal>

The server takes two snapshots 500 ms apart and computes:

$$\text{CPU%} = \left(1 - \frac{\Delta\text{idle}}{\Delta\text{total}}\right) \times 100$$

Memory (/proc/meminfo)

used = MemTotal − MemAvailable

MemAvailable is preferred over MemFree because it includes memory that can be quickly reclaimed from the page cache.

Disk (statvfs)

used  = f_blocks × f_frsize − f_bfree × f_frsize
total = f_blocks × f_frsize

f_bfree (not f_bavail) is used so that space reserved for root is counted as used.

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Configuration

Setting	Default	How to change
Server listen address	0.0.0.0:50051	Edit RunServer() in telemetry_server.cpp
Client target address	localhost:50051	Pass as first CLI argument
CPU sample window	500 ms	Change the sleep_for duration in getCpuUsagePercent()
Disk mount point	/	Change the path argument to readDiskSnapshot()

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Security Notes

• The channel uses InsecureChannelCredentials (plaintext) for simplicity.
  For production, replace with grpc::SslCredentials on the client and
  grpc::SslServerCredentials on the server.
• The server reads only from /proc/stat, /proc/meminfo, and calls statvfs("/") — all read-only, no elevated privileges required.