particlepi

Particle Pi Agent

This program supervises the Particle firmware executable running on Raspberry Pi.

Architecture

Particle Pi is a Ruby application. The logic lives inside

The Agent is an executable that runs as a background service (daemon). The agent executable is <bin/agent> and does things like command line parsing. It delegates to the Daemon class to manage a PID file, a log file and fork the process to the background.

The service description for the Agent is a System V init script in <init/particlepi>. I tried making a systemd service but couldn't find the right documentation to set that up.

Installing the service

sudo cp init/particlepi /etc/init.d
sudo ln -s $PWD/bin/agent /usr/local/bin/particlepi-agent
sudo insserv particlepi

After updating the init/particlepi script run:

sudo systemctl daemon-reload

Note: update-rc.d is deprecated. Use insserv instead.

Start the service

sudo service particlepi start

Other commands:

$ sudo service particlepi
Usage: /etc/init.d/particlepi {start|stop|restart|status}

Releasing software to a Debian personal package archive (PPA)

Our PPA is https://launchpad.net/~particleio/+archive/ubuntu/particlepi

1. Create an account on Launchpad
2. Create a team on Launchpad
3. Create a PPA on Launchpad https://help.launchpad.net/Packaging/PPA/BuildingASourcePackage
4. Upload a source package to Launchpad https://help.launchpad.net/Packaging/PPA/Uploading
5. Launchpad will build your package

To get added to the Launchpad team, launch https://launchpad.net/people/+me, register an account and ask one of the existing team members to add you to the particleio team.

Development notes

Communicate with child processes https://www.rubytapas.com/2016/06/16/episode-419-subprocesses-part-4-redirection/

` input, output = IO.pipe

pid = Process.spawm "exec", "arg", out: output

Process.waitpid(pid) input.close input.read `

` rd, wr = IO.pipe

if fork wr.close puts "Starting read" puts "Parent got: <#{rd.read}>" rd.close Process.wait else rd.close sleep 1 puts "Sending message to parent" wr.write "Hi Dad" wr.close end `

Trap SIGCHLD when child exits https://www.rubytapas.com/2016/06/30/episode-423-subprocesses-part-5-sigchld/

trap("CHLD") do pid = Process.waitpid(-1) pids[pid] = :done end