arcline-uptime

Lightweight uptime monitor for HTTP and TCP endpoints. Polls on a schedule, stores results in SQLite, sends alerts via Discord, Slack, email, ntfy, or Gotify. Includes an embedded web dashboard.

No external services required — runs as a single binary on any Linux server.

Features

• HTTP monitors — status code, optional body string check, response time threshold
• HTTP POST/PUT with custom body and headers
• TCP monitors — dial timeout
• TLS certificate expiry alerts
• DNS resolution checks with optional expected IP assertion
• Discord / Slack webhook alerts
• SMTP email alerts (multiple recipients, STARTTLS)
• ntfy.sh push notifications
• Gotify push notifications
• Per-monitor alert routing
• Maintenance windows (suppress alerts during scheduled downtime)
• Alert cooldown (no spam on sustained outages)
• Recovery alerts ("Main Website is back up, was down 12m 34s")
• Embedded web dashboard with history sparklines and incident log
• Public status page (no auth)
• Prometheus /metrics endpoint
• SQLite storage with configurable retention
• Single static binary — no CGO, cross-compiles easily

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Quick start

# Build
make build

# Create your config
cp uptime.example.yaml uptime.yaml
$EDITOR uptime.yaml

# Run
./arcline-uptime start --config uptime.yaml

# One-off check without starting the daemon
./arcline-uptime check --config uptime.yaml --monitor "Main Website"

# List configured monitors
./arcline-uptime list --config uptime.yaml

Dashboard available at http://localhost:8081 (configure dashboard.listen).

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Installation (Linux server)

1. Build or download the binary

# Build for the current system
make build

# Cross-compile for Linux amd64
make linux-amd64

# Cross-compile for Linux arm64
make linux-arm64

2. Install

# Create a dedicated user
useradd -r -s /usr/sbin/nologin -d /opt/arcline-uptime arcline

# Copy binary and config
mkdir -p /opt/arcline-uptime
install -m 0755 arcline-uptime /opt/arcline-uptime/arcline-uptime
cp uptime.example.yaml /opt/arcline-uptime/uptime.yaml
chown -R arcline:arcline /opt/arcline-uptime

# Edit your config
$EDITOR /opt/arcline-uptime/uptime.yaml

3. Configure systemd

cp arcline-uptime.service /etc/systemd/system/
systemctl daemon-reload
systemctl enable --now arcline-uptime
systemctl status arcline-uptime
journalctl -u arcline-uptime -f

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Configuration reference

global

Key	Default	Description
check_interval	60	Seconds between checks (can be overridden per monitor)
timeout	10	Seconds per probe (can be overridden per monitor)
alert_cooldown	300	Seconds between repeat DOWN alerts for the same monitor
retention_days	0	Delete check records older than this; 0 keeps forever
log_format	text	text for human-readable, json for structured output

alerts

Each entry in the alerts list defines one notification channel.

Key	Required for	Description
name	—	Optional name for per-monitor routing
type	all	discord, slack, email, ntfy, gotify
webhook_url	discord/slack	Full webhook URL
smtp_host	email	SMTP server hostname
smtp_port	email	SMTP port (587 for STARTTLS)
from	email	Sender address
to	email	Recipient(s); accepts a single string or a list
username	email	SMTP auth username
password	email	SMTP auth password
url	ntfy/gotify	ntfy topic URL or Gotify server base URL
token	ntfy/gotify	Bearer token (ntfy) or app token (Gotify)
priority	gotify	Notification priority 1–10; default 5

monitors

Key	Type	Required	Description
name	string	✓	Unique display name
type	string	✓	http, tcp, tls, dns
url	string	http	Full URL to probe
method	string	—	HTTP method; default GET
body	string	—	HTTP request body
headers	map	—	Additional HTTP request headers
expected_status	int	—	Expected HTTP status code; default 200
contains	string	—	Assert response body contains this string
host	string	tcp/tls/dns	Hostname
port	int	tcp/tls	Port number
expiry_warning_days	int	—	Alert when TLS cert expires within N days; default 14
expected_ip	string	—	DNS: assert this IP is in the results
max_response_ms	int	—	Alert if response time exceeds this; 0 disables
interval	int	—	Override global check_interval for this monitor
timeout	int	—	Override global timeout for this monitor
alert_names	list	—	Route alerts only to these named alerters; empty = all
maintenance	list	—	Suppress alerts during these time windows

Maintenance windows

maintenance:
  - days: [mon, tue, wed, thu, fri]   # weekday names (3-letter), or "*" for all
    start: "23:00"                     # HH:MM in server local time
    end: "01:00"                       # supports overnight ranges

dashboard

Key	Default	Description
enabled	false	Start the web dashboard
listen	:8081	Address to listen on
username	—	Basic auth username; leave empty to disable auth
password	—	Basic auth password

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Dashboard routes

Route	Auth	Description
/	✓	Current status table with 24h/7d/30d uptime
/history	✓	Response time sparklines per monitor
/incidents	✓	Incident log — all outage periods with duration
/metrics	—	Prometheus-compatible text metrics
/status	—	Public status page (no sensitive details)

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Alert formats

DOWN alert:

[DOWN] Main Website
expected status 200, got 503
Checked at 2026-03-21 14:32:01 UTC
Response time: 8043ms

Recovery alert:

[UP] Main Website is back up
Was down for 12m 34s
Recovered at 2026-03-21 14:44:35 UTC

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Prometheus metrics

# HELP arcline_uptime_up Whether the last check succeeded (1=up, 0=down)
arcline_uptime_up{monitor="Main Website"} 1
arcline_uptime_up{monitor="SSH"} 0

# HELP arcline_uptime_response_ms Response time of the last check in milliseconds
arcline_uptime_response_ms{monitor="Main Website"} 145

# HELP arcline_uptime_uptime_24h Uptime percentage over the last 24 hours
arcline_uptime_uptime_24h{monitor="Main Website"} 99.8600

# HELP arcline_uptime_uptime_7d Uptime percentage over the last 7 days
arcline_uptime_uptime_7d{monitor="Main Website"} 99.9200

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Building

make build          # binary in current directory
make linux-amd64    # arcline-uptime-linux-amd64
make linux-arm64    # arcline-uptime-linux-arm64
make all            # both cross-compile targets
make test           # run tests
make clean          # remove binaries

No CGO is required. Cross-compilation works without a C toolchain.

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License

MIT — see LICENSE.