Alexa Chromecast Skill
Allows Amazon Alexa to control Google Chromecast
This skill supports controlling a single Chromecast or multiple Chromecasts in different rooms. Each Alexa device can be set to control a different room. This is done by matching the room name to your Chromecast device's name. E.g. If your Chromecast is named: "Master Bedroom TV", then set the Alexa room to control to "Master Bedroom"
The following will then pause the Chromecast in the Master Bedroom:
Alexa, ask Chromecast to pause
You can control another room by saying something like:
Alexa, ask the Chromecast to pause in the Media Room
To change the room a particular Alexa device controls you can say:
Alexa, ask the Chromecast to set the room
Here are some example voice commands:
Alexa, tell Chromecast to play
Alexa, tell Chromecast to play songs by Macklemore
Alexa, tell Chromecast to play maroon 5 playlist
Alexa, tell Chromecast to play The Matrix trailer
Alexa, tell Chromecast to set the volume to 5
Alexa, tell Chromecast to stop
Alexa, ask the Chromecast in the Media Room to stop
Alexa, ask the Chromecast to play in the Media Room
How it works
Alexa skills run in the cloud, but this skill needs to be on your local network to control the Chromecast. This skill implements a hybrid approach: the command is handled by Alexa on AWS, which sends a notification to your local server.
The Lambda component is in
src/lambda, and the local component is in
Both the Chromecast and the Raspberry Pi (or whatever the local notification handler will run on) MUST be on the same network in order for the Chromecast to be discoverable.
Installation requires a UNIX environment with:
- Python 3.7
Setup and installation
Build the AWS Lambda Function
- Create an Amazon Web Services account
- Run aws-setup.sh to create a Role, Lambda Function, and SNS Topic. (It will run
aws configure, so have an key id and access key ready)
Setup the Alexa Skill
- Go to ASK Console and choose "Create Skill"
- Select "Custom" and "Provision your own", then click "Create skill". On the template screen just use the "Hello World Skill" template
- Click on "Interaction Model" in the left menu, then "JSON Editor"
- Copy and paste the content from
config/interaction_model.jsoninto the editor, then click "Save Model"
- Click on "Endpoint" in the left menu. Enter the Lambda function ARN by the aws-setup.sh. Click "Save Endpoints"
- Click on "Invocation" in the left menu. Click on "Build Model"
- Click on the "Test" tab. Enter
Install the local application which control the Chromecasts
- Install local dependencies with
sudo pip3 install -r ./src/local/requirements.txt
./start.shto start the listener, or
./docker-start.shto run in an interactive docker session. Or
./docker-start.sh -dto run as a service. The service attempts to AWS SNS using UPNP. If UPNP is disabled in your network you can specify a port.
./start.sh -p 30000To see other options run
When run you should see something like the following:
2020-07-12 11:10:40,688 - root - INFO - Starting Alexa Chromecast listener... 2020-07-12 11:10:40,688 - local.ChromecastSkill - INFO - Finding Chromecasts... 2020-07-12 11:10:45,696 - pychromecast - INFO - Querying device status 2020-07-12 11:10:45,727 - pychromecast - INFO - Querying device status 2020-07-12 11:10:45,767 - local.ChromecastSkill - INFO - Found Media Room TV 2020-07-12 11:10:45,768 - local.ChromecastSkill - INFO - Found Living Room TV 2020-07-12 11:10:45,769 - local.ChromecastSkill - INFO - 2 Chromecasts found 2020-07-12 11:10:45,809 - botocore.credentials - INFO - Found credentials in environment variables. 2020-07-12 11:10:46,967 - local.SkillSubscriber - INFO - Listening on http://22.214.171.124:30000 2020-07-12 11:10:46,968 - local.SkillSubscriber - INFO - Subscribing for Alexa commands... 2020-07-12 11:10:47,344 - local.SkillSubscriber - INFO - Received subscription confirmation... 2020-07-12 11:10:47,431 - local.SkillSubscriber - INFO - Subscribed.
- Say "Alexa ask Chromecast to play" The skill will take you through any required room setup.
The skill subscriber can be run with docker:
./docker-start.sh - for an interactive session
./docker-start.sh -d - to run as a service
The skill subscriber (local) uses these environment variables:
- AWS_SNS_TOPIC_ARN - AWS SNS Topic ARN (can be found in the
.envfile after running
- AWS_ACCESS_KEY_ID - AWS User Access Key
- AWS_SECRET_ACCESS_KEY - AWS Secret Access Key
- AWS_DEFAULT_REGION - AWS Lambda and SNS Region (e.g. eu-west-1)
If you have run
aws configure, you will not need to set AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, or AWS_DEFAULT_REGION.
Sets up an AWS environment for the Alexa Skill:
- Creates an IAM role for Alexa (with permissions for SNS)
- Creates an SNS topic to communicate over
- Creates an S3 persistent store for persisting the room to Alexa device mapping
- Creates a Lambda function
Creates a lambda-bundle.zip, which can be uploaded to an AWS Lambda function.
Runs build-lambda-bundle and automatically uploads the bundle to AWS Lambda.
"No Chromecasts found"
When the local service starts it searches for Chromecasts on the network. If there are no ChromeCasts found, it will exit.
To fix this, you must confirm that the Chromecast is on and working, make sure you can access it from your phone, and make sure that everything is on the same network.
To debug, a tool to search and list found ChomeCasts is provided at
./search-chromecasts (make sure to make it executable with
chmod +x ./search-chromecasts).
Local listener fails to subscribe
If the local listener fails to subscribe (no subscribe messages or an error) then the Chromecasts won't receive commands from Alexa By default the local listener uses UPNP and a dynamic port to establish an external connection, you can override this if required.
- Check UPNP is enabled/allowed on your network
- If UPNP is not enabled or working try and manually specify a port, and ensure your firewall/router is configured to allow external access to this port
e.g. to use port 30000 run
./start.sh -p 30000or
./docker-start.sh -p 30000
- Log into the AWS console and check the SNS topic is setup, and check the Cloud Watch logs for your the lambda function for any errors.
Alexa had an error launching the skill or processing a command
- Try redeploying the lambda skill.
- If that didn't work go to the AWS Console and check the CloudWatch logs associated with the lambda function
Alexa accepted the command but it didn't seem to work
- Check the local listener output, it should show the received command and any error that was encountered
- To check the docker service logs run something like
docker logs alexa_chromecast --since=30m, which shows the logs for the last 30 minutes