🦸‍♂️ Homelander

Simple command supervision powered by OTP supervisors and the Erlang runtime.
Run homelander my.conf, or just homelander to use ~/.homelanderrc

# simple command, long-running
spotifyd --no-daemon

# recurring command: alert if battery level low, checks every 5 minutes
[ $(pmset -g batt | grep -Eo "\d+%" | cut -d% -f1) -le 10 ] && say 'Battery low' ; sleep 300

# complex command using attributes
(
  command say "hello $name." && sleep 150
  env name=dave
  cd /bin
)

Features

• Self-contained standalone executable
• Dead simple configuration
• Runs commands in a shell environment, allowing easy log redirection, or recurring tasks using sleep
• Robustness provided by supervisor trees from Erlang/OTP
• Can match patterns in command output and trigger a restart (e.g. error message, etc.) using the restart_on attribute
• Reloads config file when modified and makes the necessary changes on the fly if watchman is installed and config directory is watched
• Uses exponential backoff when supervised command keeps failing

Installation

Standalone executables for Linux and macOS 64-bit are available in the Releases section, generated using makeself.

Or you can build it yourself

# to get a portable binary with no dependency on Erlang (any UNIX-compatible system)
./install-makeself.sh path/to/bin/directory

# or to get an escript that requires Erlang to run (any system with Erlang installed)
./install-escript.sh path/to/bin/directory

# then...
path/to/bin/directory/homelander my.conf

Command attributes

For complex commands, these attributes can be specified

name	type	description
command	string representing a valid shell command	Command to run in /bin/sh
cd	string representing a valid directory	Directory to use as the current directory when running the command
cooldown	integer in milliseconds	Cooldown in milliseconds between two restarts. 0 will restart the command right away. By default, Homelander uses exponential backoff
env	string like key=my value:)	Sets one environment variable. Can be repeated multiple times
restart_on	regexp (PCRE described here)	Pattern to match against the command's stdout. Homelander will kill and restart the command on match

Development

mix test
mix escript.build && ./homelander config.sample