Read Google Calendar from HomeAssistant AppDaemon

Introduction

The aim of this project is to provide a simpler view of the upcoming entries in a Google Calendar and have these display in HomeAssistant dashboard, or where-ever you want them. This script pulls the next 10 calendar entries, generates a simple HTML file from them and then this can be displayed where-ever needed.

Credits

The code to read the calendar is taken from Google's developer sample code, modified a bit.

Open items

• A lot of clean up and error handling
• Nicer installation - this is a bit hacky
• Perhaps an AppDaemon Dashboard would be prettier than the static HTML generated below
• The HTML could be a lot prettier anyway

Configuration & Installation

Google Calendar Authentication

Follow Google's developer documentation to get set up. You need to enable the API and get access to your calendar. This will create the credentials.json and a token.json files. I have not found a way to create these in HA so I did this on the desktop and copied them over. You will also need your calendar ID from Google, see Secrets below.

Secrets

The fake_secrets.py file has an example of what secrets the script needs to be supplied - the CALENDAR_ID which you will get from Google specific for your calendar. The code actually uses a my_secrets.py file and obviously you need to make this with your own version of the secrets.

Obviously my secrets are not in the repository.

AppDaemon Installation

The docs for AppDaemon in HomeAssistant contain a lot of words, but lack some detail how to actually get a script set up and running. Here we go.

• Install AppDaemon following the instructions
• Add Visual Studio Code Server extension to HA. This makes editing a lot easier.
• Edit the file /config/appdaemon/apps/apps.yaml and add the following section:

calendar_reader:
  module: calendar_reader
  class: CalendarReader

• Move or merge the contents of requirements.txt into the folder /config/appdaemon. This will cause AppDaemon to install the dependencies for your script.
• Move the files calendar_reader.py, my_secrets.py, credentials.json, token.json into the /config/appdaemon/apps/apps.yaml folder.
• Edit my_secrets.py to contain the correct CALENDAR_ID. See fake_secrets.py for a template what this should look like.
• Create a folder /config/www/calendar. Note that this is actually the /local/calendarfolder when viewed from the HomeAssistant Dashboard configuration
• At this point the AppDaeomon script should run - monitor this in AppDaemon's console
• AppDaemon triggers the script automatically if it is changed - so trigger this by making a minor edit and saving the file

HomeAssistant Configuration

• In HomeAssistant dashboard add a Web Page card and add the following code

type: iframe
url: /local/calendar/index6.html
aspect_ratio: 100%

• At this point everything should work. It might take a minute or two for everything to sync, but sync it should.

The Code

Some notes on the coding.

Platform Independence

Running on HomeAssistant is not a very friendly debug environment so I made an attempt to abstract the code to run on any other system. This was very helpful as getting the link to Google Calendar working right was not trivial. For this I did not need any HA capabilities but there was a certain amount of porting work to get HA running even when the desktop version worked, so having some abstraction was helpful.

A bit hacky, but this is how it works:

    if __name__ == FILE_NAME: 
        def initialize(self):
            # This will run on HomeAssistant
            self.log(f"Hello from AppDaemon {__name__}")
            self.run_every(self.run_task, "now", 15 * 60)
    else:
        def initialize(self):
            # This will run on any other Python host
            self.run_task(None)

If anyone knows a better way, let me know.

Writing HTML

There are a bunch of Python frameworks but none seemed right for this simple case so I just use Python f-strings.