Hey everyone,
wasn’t really sure where to put this, but I’ve been searching for a way to call HA scripts from my Google Home with parameters, but without IFTTT which always comes up as the solution and I haven’t been able to find anyone showing another way of doing it so I went digging on my own and here’s what I found and was able to do (spoiler: I got it mostly working). I hope someone finds it useful and possibly expands (or collaborates). Apologies for the very text-heavy post.
First off, why would I want to do this? Well, let’s say for example I want to create timers, when I’m putting a frozen pizza in the oven, when I’m boiling pasta, … Or possibly something non-cooking related 
Google by default knows how to set a timer, however what will happen at the end is it will have that annoying chime and it will go until I dismiss it. I find it very annoying.
A better alternative would to have my lights flash when the timer is over, maybe even if I’m watching something pause that and so on.
So I can create a script in HA that takes in a parameter for the duration of the timer and call it from HA no problem. However if I expose that script to Google Assistant, there doesn’t seem to be a way to tell it how long the timer should be.
IFTTT does have a way to do this, however since they introduced the change to only allow 3 applets for free, so if you don’t want to pay for more IFTTT applets, you’re stuck.
So I initially had the idea of using DialogFlow to create a bot that would call a webhook that passes the parameter(s) to HA scripts. However, since the last time I played with DialogFlow, Google has gone the paid way as well and, while you can have a free trial of DialogFlow, you will ultimately again need to pay for it.
Instead, I saw that Google Actions actually has all the basics for free. You can create actions and give it a bunch of example phrases, define what’s the parameter in the phrase and it will happily employ it’s Natural Language Understanding to create your actions.
So I set off to create a Google Actions project that would handle my custom commands.
One of my concerns here was that, as I had already setup a Google Actions project for my regular HA integration so my Google Assistant and Home Assistant are connected, I called this project (you guessed it) Jarvis and, it is a very minor nitpick, but I didn’t want to change the name to something else, but I also didn’t want this other Google Actions project to be named anything other than Jarvis and you can’t merge a Smart Home project with another project.
Thankfully, this is not a problem, you can just name them both Jarvis and they will both work at the same time! Both my Smart Home Jarvis and Custom commands Jarvis are working at the same time
Second thing that I was trying to “fix” and unfortunately I was not able to is Google’s intention of bot invocation being that you would say Hey Google, let me talk to Jarvis, then when it gets your bot you tell the bot your command, or you directly say Hey Google, ask Jarvis to [your custom command].
When you setup a command, there is a part to setup deeplink, however that seems to only be for the second style of invocation I mentioned here, even when you set it up you are still not able to just say something like Hey Google, [my custom command].
This makes it a deal breaker for some people and it’s not great for me either, however I have not find a way around it yet.
To rub salt on the wounds, even if you’re ok with the invocation part, Google will always respond with Getting the test version of Jarvis followed by a short pause, followed by a response from your Jarvis.
Would love to hear if someone has a workaround for this and if I find something will post back.
But, moving on to how I set this up.
If you go to Google Actions and create a new project (same as for the regular HA integration for Google Assistant) but when it asks the type of project, select Custom.
I’m not going to go into the detail here, but basically you need to create a custom command, and custom type for your parameters (unless your parameters are numbers or dates which Google has built in types for). If anyone wants details on this part I’m happy to provide the info, but to keep this post … well, it’s already not brief, but you know, not a kilometer of text I will just say that basically there’s a few things there you can play with and ultimately, you set the webhook for what’s going to handle your requests.
Now comes the HA part where I also need help from someone more familiar with HA to more tightly integrate this into HA as I have it completely separate from HA.
For my webhook, for now, I set up a simple PHP website, as my HA is behind an Nginx that acts as a proxy, and I just added another website to the Nginx that handles Google Assistant commands now.
There are three parts to that webhook handler - the parsing of incoming data from Google Assistant, sending it to Home Assistant and finally responding to Google on what next.
Again, I’m going to omit details for the sake of brevity, but here’s the overview of these.
Google Assistant will pass in data to your webhook as a JSON string in the body of the request, it will have an identifier of which action was invoked, as well as the method of invocation, and it will have “params” JSON object that will have the parameters nicely parsed, in fact here’s what the params object I receive for my custom timer looks like:
"params": {
"duration": {
"original": "2 minutes",
"resolved": "2 minutes"
}
}
(I have only one parameter, called duration and I said Hey Google, ask Jarvis to set timer for 2 minutes)
It will also send you the full original query as well as a bunch of other useful and less useful info.
So at this point you need to call Home Assistant. In my above example, there’s no easy way for a random person to translate 2 minutes into 00:02:00 that would work in HA, although I suspect there will be a higher proportion of people who’ll be able to handle this seeing as HA does lean into Jinja and things like this.
But anyway, your webhook will need to either process things like this, or just hand off to HA to do the processing.
Here’s the part where I made it completely separate from HA. I have a separate app that calls the HA Rest Api, the URL being:
https://my_ha_url/api/services/script/name_of_my_script
and it’s a POST with a long-live access token in the Authorization header in the format Bearer myLongLivedToken, with the body being a JSON object with my script parameters.
This works, but I feel like it would be nicer if HA was able to handle this (after all, the Smart Home Google Assistant integration works in the same way, Google sends requests and HA responds). However, my Python is rusty as well as I’m still not well-versed in the HA architecture.
Note that this is a blocking call, the API will not return until the script is finished. I didn’t test, but I suspect same as calling from within HA, if you want a non-blocking script call you can use the service to turn on the script.
Anyway, now that you’ve called your HA script, your HA is doing exactly what you want, you’ve done it, right?
Well, almost, you also probably want Google to respond with something, in my example Setting timer for x minutes. Even if you don’t want anything though, you still need to respond to Google as it will expect this (most likely) to be a conversation and it will continue listening for input.
To handle this, you just need to return a JSON object in the body of your response.
Here’s an example of my response to the above mentioned request and I’ll explain below:
{
"session": {
"id": "[invocationSessionId]",
"params": {}
},
"prompt": {
"override": false,
"firstSimple": {
"speech": "Setting custom timer for 2 minutes.",
"text": ""
}
},
"scene": {
"name": "[invocationSceneName]",
"slots": {},
"next": {
"name": "actions.scene.END_CONVERSATION"
}
}
}
Again, I will just go through the most important bits here.
Remember how I said Google will send you some other useful information? Well, one of those is the session id, another one is the scene name.
The session id is just a session id, you take it from the original request and you put it in your response.
The scene name is kind of the same, however there are a couple extra things:
- the name of the scene is going to be something like
actions.scene.START_CONVERSATIONso you’ll know what the scene you’re in is, although I don’t think that’s going to be super useful - the
nextobject in there tells Google what to do next and, as you can see in my example, I request to end the conversation. This will close the microphone as well as the conversation with the bot. If you don’t do this, the Google Home might still have the bot answering the next query instead of Google Home and it will keep listening for input
Finally, the prompt object of the respone is what Google will say in response. I take the value of the parameter and append it to the phrase Setting custom timer for . Ideally this would actually make sure that’s what’s happening, but this is a POC
The speech is going to be your spoken text. If you leave text empty, it will be the same as speech, however if you want text (on a display device) to be different than the spoken text you can set them both.
And that’s pretty much it.
Now would be a great time for a nice demo, but I fear no one is going to read to here even, let alone watch a demo which would be more work to do so I’m gonna go now If anyone found this useful and would like more info, has questions, wants that demo or anything else, please do let me know.
I think it would be cool if HA could handle calling scripts with parameters in the same “kind-of-out-of-the-box” way that it handles other Google Assistant integrations.