backrun

Run other (whitelisted) programs/scripts in background (and maybe as another userid) and save stdout/stderr in log. You may need this when you want to start other long-running scripts (like sync databases) from web-UI.

Install

# for this user only
pipx install backrun

# for all users
sudo PIPX_HOME=/opt/pipx PIPX_BIN_DIR=/usr/local/bin pipx install backrun

# old fashioned way
pip3 install backrun

Run background tasks

Prepare config file backrun.toml, and run backrun.

When you need to start some background process, do this:

echo script1 > /var/backrun/task/123

This will create task file to run script1 with id 123.

Almost immediately backrun will start to execute script and write stdout/stderr to /var/backrun/tasklog/123.log.

When script will finish, backrun will delete task file.

Details

Script will be executed with uid of backrun script.

Backrun reads only first like of taskfile, so you can put everything (any text, YAML, JSON) starting with 2nd line and script can read it.

script will get environment of backrun. backrun will set two new environment variables for script: TASKID - if of task (e.g. "123"), TASKFILE - path to task file. If user is set, HOME variable is redefined too.

Example files

config file

Config file name is either passed as first argument to backrun or first existing file in: ./backrun.toml, ~/backrun.toml, /etc/backrun.toml.

taskdir = "/var/backrun/task"
logdir = "/var/backrun/tasklog"
logfile = '/var/backrun/backrun.log'

[scripts]
    [scripts.script1]
    path="/usr/local/bin/script1.sh"

    [scripts.script2]
    path="/usr/local/bin/script1.sh"
    user="myuser"

script file (script1.sh)

#!/bin/bash

log(){
    echo `date "+%Y-%m-%d %H:%M:%S"` $*
}

log started as user `whoami`
sleep 10
>&2 log "error"
log finished

systemd service file

change User and ExecStart

[Unit]
Description=backrun: run whitelisted scripts in background

[Service]
ExecStart=/usr/local/bin/backrun
# User=xenon

[Install]
WantedBy=multi-user.target