Some Docker stuff

I want to extend my Xmas Lights project so I can record when the lights have been on/off.  I figure a database is the best way to do this, so not wanting to learn something like Mongo at this point, I figured a Postgres DB was probably easiest.  Not wishing to get into the installation process I wondered whether Docker might hold a quick solution to my problem.  Here are a few things I learned.

Platform:

Windows 8.1 running HyperV - LAN IP 192.168.0.60

Linux VM : "CentOS Linux release 7.2.1511 (Core)", logged in as "root"

Setup docker

sudo yum install docker

Configure host firewall

firewall-cmd --permanent --zone=trusted --change-interface=docker0

firewall-cmd --permanent --zone=trusted --add-port=4243/tcp

firewall-cmd --reload

(interestingly, I found that I couldn't start containers with firewalld disabled)

Create Postgres container

docker run --name postgres -p 5432:5432 -d postgres

(I should really use "-e POSTGRES_PASSWORD=xxx", but omitting it seems to just allow the "postgres" login to work with a blank password)

docker inspect postgres

(output contains IP address : "IPAddress": "172.17.0.2".  This is the Docker internal address.  It appears that by default other containers on this internal network can see each other)

Create PGAdmin4 container

docker run --name pgadmin --link 1337c2af44ac:postgres -p 5050:5050 -d fenglc/pgadmin4

(not sure about the --link bit, I think the version of Docker I'm using is much newer and handles internal networking differently, but this command worked OK)

Use WebUI to create a database "xmas16" and a table "messages" with columns ID(integer) and message(text).  Put some test data in it.

Web browser to http://192.168.0.60/browser/ (IP of host CentOS VM) to access PGAdmin console.  Connected PGAdmin to Postgres server "172.17.0.2"

In Python, installed psycopg2 module using PIP

Python code (running on separate test PC or RPi):

import psycopg2

conn = psycopg2.connect("dbname='xmas16' user='postgres' host='192.168.0.60' password=''")

cur = conn.cursor()

cur.execute("select * from messages")

rows = cur.fetchall()

for row in rows:

    print (row[1])

Done!  My app wrote my test messages to the stdout.  Learning Docker took an hour or two, especially the firewalld bit, but I have a full PoC rig up and running with very little effort.  Considering my objective is to capture non-sensitive data from a Xmas light project for fun it's more than adequate.

Xmas lights controller 2016

Last year I decided to use a Raspberry Pi and a relay board to switch my Christmas lights on and off.  This had two benefits; the first is that the kids thought it was super cool, especially my niece who turned on our lights from the other end of the country while watching it on Skype, and secondly it became straightforward to schedule them to switch on and off at multiple different times each day.

Anyway, it's now mid November and it's gotten too cold and dark for it to be fun outside after work so I've been looking for indoors projects to do, which inevitably led to the Pi.  During the last year I've been playing with a bit more Python (a welcome break from the whole lotta Powershell we've been doing), and have recently touched on Cordova for mobile apps, so wanted to look at something which might tie in with that, so I decided to resurrect the Xmas Lights project for this year, but build it with a bit more care this time around.

I've been hacking away for the last couple of evenings, and have got the board into what I think is reasonable shape.  It's a bit early in the year to have the Christmas lights on outside still, so this post just covers the Pi and relay board.  I might make a YouTube video nearer Christmas when i plug it all in.

So, here's the board:

It's an "8 Channel 5V Active Low Relay Module Board" which sounds advanced but is actually the cheapest piece of crap I could find on eBay at the time and cost £4.28.  That said, it's been fine, although it's not earthed or particularly well assembled, so I'm not sure I'd want to run 240v through it...  The black box is a Pi A+ that I've had kicking around for a while since I bricked my original B and haven't soldered the headers onto my Zero

You might be able to see in the pictures, but the pin mapping is:

RelayBoard   Pi-pin  GPIO

GND <--------> 6  <--> Ground

IN1 <--------> 37 <--> 26

IN2 <--------> 35 <--> 19

IN3 <--------> 33 <--> 13

IN4 <--------> 31 <-->  6

IN5 <--------> 29 <-->  5

IN6 <--------> 40 <--> 21

IN7 <--------> 38 <--> 20

IN8 <--------> 36 <--> 16

VCC <--------> 2  <--> +5v

Like last year, the project is based on Python Flask.  The folder structure and code are at the end of this post.

The main differences since last year in views.py are that it uses more HTTP verbs in the bindings, uses dictionary objects to manage the pins states and returns proper JSON documents to communicate state requests between the client and server.  The other big difference is in lights.html that is now using bootstrap (so my site can look just like everyone else's...), much smarter AJAX to send state requests and a UI to render the current state based the server response from each request.  

As the state is actually derived from querying the GPIO pins for their value, this is clearly not thread safe in any way so I'm not sure there's a huge amount of value in taking the UI further, but I might look into using web sockets or something and pushing updates to clients in future.

I'll have to look into the finer points of the weird pseudo JS that cordova uses, but if it's straightforward to translate my Javascript then I might also dip my toe in the waters of "native" mobile apps.

run.py

|-app

  |-templates

  | |-help.html

  | |-lights.html

  |-__init__.py

  |-views.py

and here is the code:

run.py

	#!/usr/bin/env python
	#!flask/bin/python
	from app import app
	app.run(debug=True, host='0.0.0.0', port=80)

__init__.py

	from flask import Flask
	import RPi.GPIO as GPIO
	app = Flask(__name__)
	from app import views
	GPIO.setwarnings(False)
	GPIO.setmode(GPIO.BCM)
	pins = {"26":1, "19":1, "13":1, "6":1, "5":1, "21":1, "20":1, "16":1}
	for p in pins:
	GPIO.setup(int(p), GPIO.OUT)
	GPIO.output(int(p), pins[p])

views.py

	from app import app
	from flask import request
	import RPi.GPIO as GPIO
	from flask import render_template
	import time
	import json
	mapping = {"a":26, "b":19, "c":13, "d":6, "e":5, "f":21, "g":20, "h":16}
	def getState():
	relays = {"a":"x", "b":"x", "c":"x", "d":"x", "e":"x", "f":"x", "g":"x", "h":"x"}
	for m in mapping:
	if GPIO.input(mapping[m]) == 1:
	relays[m] = "off"
	else:
	relays[m] = "on"
	return relays
	def setState(newState):
	for s in newState:
	if s in mapping:
	if newState[s] == "on":
	GPIO.output(int(mapping[s]), 0)
	time.sleep(0.2)
	elif newState[s] == "off":
	GPIO.output(int(mapping[s]), 1)
	time.sleep(0.2)
	elif newState[s] == "toggle":
	if getState()[s] == 'on':
	setState({s:"off"})
	else:
	setState({s:"on"})
	time.sleep(0.2)
	else:
	#newState contains unknown relay
	print "err"
	#def setPins(pinVal):
	# pins = [26, 19, 13, 6, 5]
	# for p in pins:
	# GPIO.output(int(p), pinVal)
	# time.sleep(0.1)
	@app.route('/lights', methods=['PUT'])
	def lights_on():
	setState({"a":"on", "b":"on", "c":"on", "d":"on", "e":"on", "f":"on", "g":"on", "h":"on"})
	return json.dumps(getState())
	@app.route('/lights', methods=['DELETE'])
	def lights_off():
	setState({"a":"off", "b":"off", "c":"off", "d":"off", "e":"off", "f":"off", "g":"off", "h":"off"})
	return json.dumps(getState())
	@app.route('/lights', methods=['POST'])
	def lights_set():
	setState(request.form)
	return json.dumps(getState())
	@app.route('/', methods=['GET'])
	def jsLights():
	return render_template('lights.html')
	@app.route('/status')
	def status():
	return json.dumps(getState())
	@app.route('/help')
	def help():
	return render_template('help.html', relays=getState())

lights.html

	<html>
	<head>
	<title>Xmas Lights 2016</title>
	<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
	<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" />
	<style>
	.row-buffer{ margin-bottom: 20px; }
	</style>
	<script>
	function doAlert(lightsStatus){
	var obj = jQuery.parseJSON(lightsStatus);
	$("#lightsA").removeClass("btn-warning");
	$("#lightsB").removeClass("btn-warning");
	$("#lightsC").removeClass("btn-warning");
	$("#lightsD").removeClass("btn-warning");
	$("#lightsE").removeClass("btn-warning");
	$("#lightsF").removeClass("btn-warning");
	$("#lightsG").removeClass("btn-warning");
	$("#lightsH").removeClass("btn-warning");
	if(obj.a=="on"){ $("#lightsA").addClass("btn-warning") }
	if(obj.b=="on"){ $("#lightsB").addClass("btn-warning") }
	if(obj.c=="on"){ $("#lightsC").addClass("btn-warning") }
	if(obj.d=="on"){ $("#lightsD").addClass("btn-warning") }
	if(obj.e=="on"){ $("#lightsE").addClass("btn-warning") }
	if(obj.f=="on"){ $("#lightsF").addClass("btn-warning") }
	if(obj.g=="on"){ $("#lightsG").addClass("btn-warning") }
	if(obj.h=="on"){ $("#lightsH").addClass("btn-warning") }
	}
	$(document).ready(function() {
	$("#lightsOn").click(function() {
	$.ajax({url: "http://192.168.0.50/lights", type: "PUT"}).done(function(data) {
	doAlert(data);
	});
	});
	$("#lightsOff").click(function() {
	$.ajax({url: "http://192.168.0.50/lights", type: "DELETE"}).done(function(data) {
	doAlert(data);
	});
	});
	$("#lightsA").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"a":"toggle"} }).done(function(data) {doAlert(data)}) });
	$("#lightsB").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"b":"toggle"} }).done(function(data) {doAlert(data)}) });
	$("#lightsC").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"c":"toggle"} }).done(function(data) {doAlert(data)}) });
	$("#lightsD").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"d":"toggle"} }).done(function(data) {doAlert(data)}) });
	$("#lightsE").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"e":"toggle"} }).done(function(data) {doAlert(data)}) });
	$("#lightsF").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"f":"toggle"} }).done(function(data) {doAlert(data)}) });
	$("#lightsG").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"g":"toggle"} }).done(function(data) {doAlert(data)}) });
	$("#lightsH").click(function() { $.ajax({url: "http://192.168.0.50/lights", type: "POST", data: {"h":"toggle"} }).done(function(data) {doAlert(data)}) });
	});
	</script>
	</head>
	<body>
	<h1>Xmas 2016 lights control</h1>
	<div class="row row-buffer">
	<div class="col-sm-8">
	<button id="lightsOn" type="button" class="btn btn-primary btn-block">All lights on</button>
	</div>
	</div>
	<div class="row row-buffer">
	<div class="col-sm-8">
	<button id="lightsOff" type="button" class="btn btn-primary btn-block">All lights off</button>
	</div>
	</div>
	<div class="row">
	<div class="col-sm-1">A</div>
	<div class="col-sm-1">B</div>
	<div class="col-sm-1">C</div>
	<div class="col-sm-1">D</div>
	<div class="col-sm-1">E</div>
	<div class="col-sm-1">F</div>
	<div class="col-sm-1">G</div>
	<div class="col-sm-1">H</div>
	</div>
	<div class="row">
	<div class="col-sm-1"><button id="lightsA" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	<div class="col-sm-1"><button id="lightsB" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	<div class="col-sm-1"><button id="lightsC" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	<div class="col-sm-1"><button id="lightsD" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	<div class="col-sm-1"><button id="lightsE" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	<div class="col-sm-1"><button id="lightsF" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	<div class="col-sm-1"><button id="lightsG" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	<div class="col-sm-1"><button id="lightsH" type="button" class="btn btn-lg btn-block"><span class="glyphicon glyphicon-off"></span></button></div>
	</div>
	</body>
	</html>

help.html

	<html>
	<head>
	<title>Xmas Lights 2016 - Help</title>
	<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" />
	</head>
	<body>
	<h1>
	Xmas2016 lights controller - Help
	</h1>
	<div>
	Usage:
	<table class="table table-bordered">
	<tr>
	<td>switch all on</td><td>PUT root/lights</td>
	</tr>
	<tr>
	<td>switch all off</td><td>DELETE root/lights</td>
	</tr>
	<tr>
	<td>control relays</td><td>POST {{relays}} root/lights</td>
	</tr>
	</table>
	</div>
	</body>
	</html>

Finally a picture I took while I was messing around with my camera - you can clearly see the opto-isolators are not even vaguely straight - not a quality of board to be handling voltages and currents that could burn my house down I think.