Only1Mon

Lightweight system monitoring dashboard built with Go and Alpine.js. Single binary, zero external dependencies, real-time WebSocket streaming.

Features

• Real-time Dashboard — Drag-and-drop widgets with live metric charts (uPlot + GridStack)
• Multiple Widget Types — Chart, Table, Top (process CPU/mem), IoTop (process disk I/O)
• 7 Built-in Collectors — CPU, Memory, Disk, Network, Process, Kernel, GPU
• Per-metric Control — Enable/disable individual metrics without restarting
• Alert Engine — Configurable threshold-based alerts with EN/KO messages
• Chart Cursor Sync — Hover on one chart, all charts follow the same timestamp
• Human-readable Units — Bytes, bytes/s, %, ms, us, etc. auto-formatted
• Daemon Mode — start / stop / status with PID file management
• Nginx Ready — Built-in base_path support and -nginx config generator
• Single Binary — CGO_ENABLED=0, no cgo required (purego for macOS syscalls)
• i18n — English / Korean UI
• Dark Theme — Modern dark UI designed for always-on monitoring

Quick Start

Build

# Linux / macOS
git clone https://github.com/playok/only1mon.git
cd only1mon
make build

# Windows
git clone https://github.com/playok/only1mon.git
cd only1mon
go build -o build\only1mon.exe ./cmd/only1mon

Requires Go 1.22+. Produces build/only1mon (Linux/macOS) or build\only1mon.exe (Windows).

Run

# Foreground
./build/only1mon run

# Daemon (Linux/macOS only)
./build/only1mon start
./build/only1mon status
./build/only1mon stop

# Windows (foreground only)
build\only1mon.exe run

Open http://127.0.0.1:9923 in your browser.

Cross-compile

make build-all        # linux/darwin x amd64/arm64

go build -o build\only1mon.exe ./cmd/only1mon   # linux/darwin/windows x amd64/arm64 via GoReleaser

# GoReleaser
goreleaser build --snapshot --clean   # all platforms via GoReleaser

Configuration

Create config.yaml in the working directory (or specify with -config):

listen: "127.0.0.1:9923"
database: "only1mon.db"
base_path: "/"
pid_file: "only1mon.pid"
log_file: "only1mon.log"

Priority: config.yaml < environment variables < command-line flags.

Flag	Env Var	Default	Description
-listen	ONLY1MON_LISTEN	127.0.0.1:9923	HTTP bind address
-db	ONLY1MON_DB	only1mon.db	SQLite database path
-base-path	ONLY1MON_BASE_PATH	/	URL prefix for reverse proxy
-config	—	config.yaml	Config file path
-pid-file	—	only1mon.pid	PID file path
-log-file	—	only1mon.log	Log file path

Runtime settings (collection interval, retention, chart colors, top process count) are managed in the web UI Settings page and persisted to SQLite.

Nginx Reverse Proxy

Generate a sample nginx config:

./build/only1mon -nginx

Example output:

location /mon/ {
    proxy_pass         http://127.0.0.1:9923/;
    proxy_http_version 1.1;
    proxy_set_header   Upgrade $http_upgrade;
    proxy_set_header   Connection "upgrade";
    proxy_set_header   Host $host;
    proxy_buffering    off;
    proxy_read_timeout 86400s;
}

Set base_path: "/mon" in config.yaml to match.

Commands

only1mon start           Start as daemon (background)
only1mon stop            Stop daemon (SIGTERM)
only1mon status          Check daemon status
only1mon run             Run in foreground
only1mon version         Print version
only1mon -nginx          Print nginx reverse proxy config

Collectors

Collector	Metrics	Description
cpu	usage, user, system, iowait, idle, per-core, load avg	CPU utilization and load
memory	total, used, free, available, cached, buffers, swap	Memory and swap usage
disk	total, used, free, used_pct, read/write bytes/sec	Per-mount usage and I/O
network	bytes sent/recv, packets, errors, per-interface	Network throughput
process	top CPU, top memory, top I/O processes	Process resource ranking
kernel	context switches, interrupts, procs blocked/running	Kernel-level stats
gpu	utilization, temperature, memory, power	GPU monitoring (NVIDIA)

On first run, cpu, memory, and disk collectors are enabled by default. Other collectors are auto-enabled when you add widgets that require their metrics.

Dashboard Widgets

• Chart — Time-series line chart with uPlot. Supports multiple metrics, cursor sync across charts, unit-aware Y-axis and tooltips.
• Table — Real-time metric values in a grid with flash animations on change.
• Top — Linux top-like view: CPU bar, memory bar, swap bar, load average, top-N processes by CPU.
• IoTop — Linux iotop-like view: total read/write throughput, top-N processes by disk I/O.

Layouts are saved/loaded from the database and persist across sessions.

Alert System

Built-in alert rules monitor critical thresholds:

• CPU user > 90%, system > 50%, iowait > 30%
• Memory > 80% / 90%, swap > 1GB
• Disk > 85% / 95%
• Network errors, blocked processes, GPU temperature

Rules are managed via the API (CRUD) and evaluated on every collection cycle. Virtual filesystem mounts (/dev, /proc, /sys, /run) are automatically excluded.

Architecture

┌─────────┐    ┌─────────┐    ┌──────────┐    ┌───────────┐
│ Config  │───>│  Store   │───>│ Registry │───>│ Scheduler │
│ (YAML)  │    │ (SQLite) │    │(Collector)│   │  (loop)   │
└─────────┘    └─────────┘    └──────────┘    └─────┬─────┘
                                                     │
                              ┌───────────┐    ┌─────▼─────┐
                              │   Alert   │<───│    API    │───> HTTP
                              │  Engine   │    │ (net/http) │
                              └───────────┘    └─────┬─────┘
                                                     │
                                               ┌─────▼─────┐
                                               │ WebSocket │───> Browser
                                               │    Hub    │
                                               └───────────┘

• Backend: Go, net/http (Go 1.22 routing), SQLite (WAL mode), WebSocket
• Frontend: Alpine.js, uPlot, GridStack, vanilla JS (no build step)
• Storage: SQLite with automatic schema migrations (v1-v5)
• macOS: Process I/O via purego calling proc_pid_rusage from libSystem.B.dylib

API

Collectors

GET    /api/v1/collectors
PUT    /api/v1/collectors/{id}/enable
PUT    /api/v1/collectors/{id}/disable
PUT    /api/v1/metrics/ensure-enabled

Metrics

GET    /api/v1/metrics/available
GET    /api/v1/metrics/query?name=cpu.total.usage&from=&to=&step=
PUT    /api/v1/metrics/state/{name}/enable
PUT    /api/v1/metrics/state/{name}/disable

Alerts

GET    /api/v1/alerts
GET    /api/v1/alert-rules
POST   /api/v1/alert-rules
PUT    /api/v1/alert-rules/{id}
DELETE /api/v1/alert-rules/{id}

Dashboard & Settings

GET    /api/v1/settings
PUT    /api/v1/settings
GET    /api/v1/settings/db-info
DELETE /api/v1/settings/db-purge
GET    /api/v1/dashboard/layouts
POST   /api/v1/dashboard/layouts
GET    /api/v1/dashboard/layouts/{id}
PUT    /api/v1/dashboard/layouts/{id}
DELETE /api/v1/dashboard/layouts/{id}
GET    /api/v1/ws

Development

# Linux / macOS
make dev             # go run (foreground, auto-recompile not included)
make run             # build + run foreground
go vet ./...         # static analysis
go test ./...        # run tests

# Windows
go build -o build\only1mon.exe ./cmd/only1mon   # go run (foreground)
go build -o build\only1mon.exe ./cmd/only1mon   # build + run foreground
go run ./cmd/only1mon run                       # go run (foreground)
go vet ./...                                     # static analysis
go test ./...                                    # run tests

Adding a Collector

1. Implement the Collector interface in internal/collector/
2. Register in registerAllCollectors() in cmd/only1mon/main.go
3. Add metric descriptions in internal/collector/descriptions.go

License

MIT