http-checker

Small Bash script that checks HTTP availability of one or more domains.

For each domain it resolves all A records via dig, then sends a curl request to every resolved IP (using --resolve, so the right backend is hit regardless of DNS round-robin) and prints the result. A failed curl request is retried up to RETRY_COUNT times (default 3) with RETRY_INTERVAL seconds (default 2) between attempts; only if every attempt fails does it log an error and optionally send a Telegram notification.

Requirements

The following binaries must be available in PATH:

• dig — resolve A records
• curl — perform the requests
• jq — format the curl JSON output

Installation

sudo curl -fsSL "https://raw.githubusercontent.com/spf50p/http-checker/refs/heads/main/http-checker.sh" \
  -o /usr/local/bin/http-checker.sh \
  && chmod +x /usr/local/bin/http-checker.sh

Configuration

Settings are read from a config file that is sourced as shell, so it must use KEY=value syntax. Default path is .http-checker.conf in the current directory; override it with the HC_CONF environment variable.

# .http-checker.conf
DOMAIN=domain1.com,domain2.com,domain3.com   # comma-separated list of domains
SCHEME=https                                 # optional, defaults to https
CURL_PORT=443                                # optional, port curl connects to (443 for https, 80 for http)
CURL_TIMEOUT=5                               # optional, connect timeout in seconds
RETRY_COUNT=3                                # optional, attempts before reporting failure
RETRY_INTERVAL=2                             # optional, seconds between retries
TELEGRAM_BOT_TOKEN=<bot-token>               # optional, enables notifications
TELEGRAM_CHAT_ID=<chat-id>                   # optional, enables notifications
TELEGRAM_API_URL=https://api.telegram.org    # optional, Telegram API base URL

Variable	Required	Default	Description
DOMAIN	yes	—	Comma-separated list of domains to check
SCHEME	no	https	Request scheme (http or https)
CURL_PORT	no	443	Port curl connects to via --resolve (443 for https, 80 for http)
CURL_TIMEOUT	no	5	Curl connect timeout in seconds
RETRY_COUNT	no	3	Number of attempts per IP before reporting a failure
RETRY_INTERVAL	no	2	Seconds to wait between retries
TELEGRAM_BOT_TOKEN	no	—	Telegram bot token for notifications
TELEGRAM_CHAT_ID	no	—	Telegram chat ID for notifications
TELEGRAM_API_URL	no	https://api.telegram.org	Base URL of the Telegram Bot API
HC_CONF (env)	no	.http-checker.conf	Path to the config file

If both TELEGRAM_BOT_TOKEN and TELEGRAM_CHAT_ID are set, failures are sent to Telegram; otherwise a warning is printed and the script continues.

TELEGRAM_API_URL lets you point the Bot API requests at a different host than the default https://api.telegram.org — for example a reverse proxy/mirror used in networks where api.telegram.org is blocked. The script builds the request URL as ${TELEGRAM_API_URL}/bot${TELEGRAM_BOT_TOKEN}/sendMessage.

Usage

Check the domains from the config file:

./http-checker.sh

Override the domains via the first argument (takes precedence over the config file DOMAIN):

./http-checker.sh domain1.com
./http-checker.sh domain1.com,domain2.com

Send a test message to verify the Telegram integration:

./http-checker.sh check-tg

Output

For each resolved IP the script prints a line like:

url=https://example.com remote-ip=93.184.216.34 http-code=200 time=0.123456

License

BSD 3-Clause License