ASMT: Another Server Monitoring Tool

Live dashboard on a production Debian VM. Every panel is real data; no synthetic placeholders. Two SSL certificate rows are redacted; everything else is exactly what an operator sees.

A lightweight Linux server monitoring tool built in Go. Single static binary (~8 MB), zero runtime dependencies, ~13 MB RSS at runtime. Auto-detects services and works across every major Linux distribution.

Why another one? ASMT is designed to be a smart lens on top of the OS journal, not a replacement for it. It earns its existence by making existing truth easier to see, and it does so in roughly one tenth the memory of a typical agent. See LEARNINGS.md for the design story.

What it does

ASMT runs as a background service and continuously checks the health of your server's components. It exposes a live web dashboard and a JSON API so you can see the current state of everything at a glance.

What it monitors

Component	Checks performed
Linux OS	Disk usage, memory usage, load average
Nginx	Process running (PID + signal 0), config valid (nginx -t), HTTP probe
Apache	Process running, config valid (apachectl -t), HTTP probe
PHP-FPM	Process in /proc, socket/port responding
MariaDB	Connection alive, SELECT 1, thread count
PostgreSQL	Connection alive, SELECT 1, active connection count
Redis	PING/PONG over raw TCP, optional AUTH
WordPress	Site HTTP response, wp-cron endpoint, REST API
Custom HTTP endpoints	Status code, optional body substring, custom headers
Firewall	TCP dial to configured ports on localhost
GCP Load Balancer	Metadata server reachable, LB path probe
Log watcher	Tails log files, matches 26 known error patterns with mitigation advice

Endpoints

Endpoint	Purpose
GET /	Web dashboard (status refreshes every 5 s; logs refresh immediately on status change and every 15 min otherwise)
GET /api/status	Full JSON status of all components
GET /api/logs	Recent log warnings with mitigation advice
GET /healthz	Load balancer health check (200 OK or 503)

Supported Linux distributions

Debian, Ubuntu, Linux Mint, RHEL, CentOS, Rocky Linux, AlmaLinux, Fedora, Arch, Manjaro, Alpine, openSUSE, SLES.

Alerts

Supports log alerting, webhook (POST JSON), and email (SMTP) on status transitions.

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Install from a release (no Go required)

Run this one-liner on your server. It auto-detects your CPU architecture, fetches the latest release, and installs everything:

curl -sSL https://raw.githubusercontent.com/minspresso/asmt/main/scripts/get.sh | sudo bash

That's it. The installer:

• Detects your CPU architecture (amd64 or arm64) automatically
• Fetches the latest release version from GitHub
• Downloads the correct binary
• Detects your distro, HTTP server (nginx/Apache), and init system (systemd/OpenRC)
• Installs the binary to /opt/serverstat/
• Generates a starter config.yaml tailored to what it finds on your system
• Registers and enables the service

After installing:

# Edit the config
sudo nano /opt/serverstat/config.yaml

# Set secrets in the environment file (persists across reboots, chmod 600)
sudo nano /opt/serverstat/env
# Example contents:
#   MARIADB_DSN=monitor:password@tcp(127.0.0.1:3306)/mysql
#   REDIS_PASSWORD=secret

# Start the service (systemd)
sudo systemctl enable --now serverstat

# Or on OpenRC (Alpine)
sudo rc-update add serverstat default
sudo rc-service serverstat start

Secrets use ${ENV_VAR} expansion in config.yaml. The environment file at /opt/serverstat/env is loaded by systemd via EnvironmentFile=, so values persist across reboots. The file is created with chmod 600 (root-only readable).

Dashboard is at http://localhost:8080 (localhost only by default).

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Install from source (requires Go 1.22+)

git clone https://github.com/minspresso/asmt.git
cd asmt

make build          # produces ./serverstat binary
sudo bash scripts/install.sh

Or build and install in one step:

make install        # builds if needed, then runs install.sh

To cross-compile for a remote server:

make build-amd64    # Linux amd64
make build-arm64    # Linux arm64

Then copy the files and install remotely:

scp serverstat scripts/install.sh scripts/uninstall.sh config.yaml user@server:~/
ssh user@server 'sudo bash install.sh'

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Uninstall

# If installed via one-liner
curl -sSL https://raw.githubusercontent.com/minspresso/asmt/main/scripts/uninstall.sh | sudo bash

# If installed from source (interactive)
sudo bash scripts/uninstall.sh

# Non-interactive
sudo bash scripts/uninstall.sh -y

# Via make
make uninstall

Removes the binary, config, and service files from the system.

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Configuration

The config file lives at /opt/serverstat/config.yaml after install. A reference copy is in config.yaml at the root of this repo.

Sensitive values use ${ENV_VAR} expansion. Never hardcode secrets in config.yaml:

mariadb:
  dsn: "${MARIADB_DSN}"
redis:
  password: "${REDIS_PASSWORD}"
alerts:
  webhook:
    url: "${WEBHOOK_URL}"

Define the actual values in /opt/serverstat/env (one KEY=value per line, no quotes needed):

MARIADB_DSN=monitor:password@tcp(127.0.0.1:3306)/mysql
REDIS_PASSWORD=secret
WEBHOOK_URL=https://hooks.example.com/alert

This file is loaded by systemd on every service start and persists across reboots. After editing, restart: sudo systemctl restart serverstat.

Set language to "en" (English, default) or "ko" (Korean).

MariaDB monitoring setup

ASMT can monitor MariaDB connection health, query ability, and active thread count. If MARIADB_DSN is not set (or the first connection fails), ASMT shows "not configured" on the dashboard and stops checking. It will not retry until you restart the service.

To enable MariaDB monitoring:

1. Create a read-only monitor user in MariaDB:

CREATE USER 'monitor'@'127.0.0.1' IDENTIFIED BY 'a-strong-password';
GRANT PROCESS ON *.* TO 'monitor'@'127.0.0.1';
GRANT SELECT ON mysql.* TO 'monitor'@'127.0.0.1';
FLUSH PRIVILEGES;

PROCESS lets ASMT read thread count via SHOW STATUS. SELECT ON mysql.* is required because the DSN connects to the mysql database by default.

2. Set the DSN in the environment file:

# /opt/serverstat/env
MARIADB_DSN=monitor:a-strong-password@tcp(127.0.0.1:3306)/mysql

3. Restart the service:

sudo systemctl restart serverstat

The dashboard should now show MariaDB as green. If the DSN is wrong, the dashboard shows the "not configured" message with next steps.

To disable MariaDB monitoring entirely, set mariadb.enabled: false in config.yaml.

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Build a distributable archive

make dist                     # current platform
make dist GOARCH=arm64        # cross-compile for ARM

Produces serverstat-VERSION-linux-ARCH.tar.gz containing the binary, scripts, config, and README.

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Resource usage

Metric	Value
Binary size	~8 MB (stripped, static, no CGO)
RSS at runtime (typical)	~13 MB steady, ~16 MB peak
GOMEMLIMIT (soft GC ceiling)	64 MiB
CPU	Negligible (checks run every 30 s)

Numbers above are VmRSS and VmHWM from /proc/PID/status on a production Debian VM running nginx, WordPress, MariaDB, and PHP-FPM.

A "soft GC ceiling" of 64 MiB does not mean ASMT reserves 64 MiB. The Go runtime uses it as a hint to garbage-collect more aggressively as the heap approaches that number. Idle RSS stays around 13 MB. The headroom only matters during a crisis (see the "memory ceiling lesson" in LEARNINGS.md).

Note on systemctl status serverstat. systemd may report a much larger number (e.g. Memory: 65M). That is the service's cgroup memory, which includes kernel pagecache for the log files ASMT tails. That memory is reclaimable on demand and is not "used by" the process in any meaningful sense. The process-level RSS is what the table above quotes, and it is what the ps, top, and /proc/PID/status numbers agree on.

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Project layout

*.go              All source (flat package main, ~3500 lines)
lang/             Translation YAML files (en, ko)
web/              Dashboard HTML (embedded at build time)
scripts/
  get.sh          One-liner: detects arch, downloads latest release, installs
  install.sh      Installs from a local binary (used by get.sh and make install)
  uninstall.sh    Removes binary, config, and service files
config.yaml       Reference configuration
Makefile

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Security

Found a vulnerability? Please do not open a public issue. See SECURITY.md for the private disclosure process.

Contributing

Pull requests are welcome. Please read CONTRIBUTING.md before opening one. It covers the coding conventions, the test/lint commands CI runs, and the design principles ASMT holds itself to.

License

GNU Affero General Public License v3.0 (AGPL-3.0)

You are free to use, modify, and distribute this software, but any modified version (including use over a network) must also be released under AGPL-3.0 with its source code made available. It cannot be used in closed-source or proprietary products without a separate commercial agreement.