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Showing posts from January, 2016

12 Factor Config for .Net on Mono in a Docker

Recently I've been thinking about how to run a .Net application using Mono inside a Docker, along with this we'd like to use Twelve Factor config.

Whilst it is possible to use some library to access environment variables instead of using appSettings it becomes difficult for database and message broker URLs which other libraries may expect to find within the App.config or Web.config file.

The solution I came up with follows:
Build the application without an App.config moving the existing configuration file renaming it App.config.template. 
Substitute any environment variables you want with ${}.  E.g:
<amqp> <connections> <connection name="rabbit" server="${RABBITMQ_URL}" password="${RABBITMQ_PASSWORD}" /> </connections> </amqp>
Include within the Docker image a script named sub.sh similar to this and add it to /conf:
#!/bin/shwhile read line doeval echo "$line"done Add your config template to /conf
Then …

Howto: Node-RED Change Hue Lights Temporarily On Door Open

We fitted a LightwaveRF magnetic sensor to a door to detect whether it is open or closed. The main driver behind this was to increase the level of the hallway lights for a predetermined period of time whenever the door was opened. Since we’re using coloured lights it makes sense to put the light back to how it was once the time period as elapsed. 
Node-RED does not offer a node as a means of storing state between, but it does offer functions which have access to a context object which can be used to store state between flows. 
I’ve created a flow which listens to the `domoticz/out` MQTT topic filters messages based on their Domoticz IDX value and furthers filters on the door switches `nvalue` where 1 indicates door open and 0 indicates door closed. 
https://dl.dropboxusercontent.com/u/174818/FrontDoorLight.json
On Door Open: Retrieve state of current light and if nothing already stored, store the current bulb state in the context. Change the state of the bulb to a bright white. Res…

Howto: Node Red Subflow for Hue Bulbs

When writing some flows for Node-RED controlling my Philips Hue bulbs; I wanted to read from a bulb do some work then write that same colour back to the bulb. When you perform a GET on a bulb, you get all of the information, whilst good this means it is a bit more inconvenient to PUT that back into a bulb as that API has a slightly different resource shape where the colour mode is determined by which values are submitted.

After using a group of nodes in one flow which did exactly this, I needed the same block in another flow. So I created a sub flow by selected those nodes, clicking the hamburger menu in the top right and choosing 'Subflows > Selection to Subflow'. This replaces the selected nodes with a single node which you can edit in a 'subflows' menu group in the left pane.

Download this selection and make your own subflow:
https://dl.dropboxusercontent.com/u/174818/HueInputToOutput.json?dl=1

Automatic Kitchen Lights

We recently purchased Hue bulbs for our Kitchen they’re great, but since we already have an RFXCom 433 unit (as per my blog on automating hifi), we wanted to automate the lights and invested in a Lightwave PIR motion sensor. 

I downloaded Domoticz [http://domoticz.com/] on an SD Card for my Raspberry PI and also installed node-red [http://nodered.org/] a tool for filtering and processing MQTT messages. 
Domoticz is used to store the state of the motion sensor and is configured to emit an MQTT message whenever the state changes. 
We also wanted the lights to have a different colour depending on the time of day we enter the kitchen, for example during the evening we might want a relaxing light, meal times a white light above the dining table and during the day some multi coloured lights, but not change them if they've already on. 
For each of the time slots of the day, a template has been created containing the settings of each of the main and dining lights and will send these o…