Lambda Overview (VSK Echo Show)
The Lambda function serves as the video skill's backend. You can update the reference Lambda code locally, use the CLI tool to update, rebuild, redeploy the project, and automatically push your Lambda to AWS.
How It Works
All Lambda scripts are locally stored in the project, under your ./lambda/src folder. They are pushed to the cloud when you deploy your video skill using the CLI tool. If you successfully deploy the video skill, you will be able to locate your entire Lambda function as a single file, in the AWS console. There, you can search for your Lambda:
Click on your function name (<your-project>-lambda). Your lambda function lives inside the index.js file.
By using the CLI tool, you only need to focus on updating specific scripts stored locally (for example, you can update the video content database.js script), update, redeploy the Lambda component, and push the updated Lambda to the cloud.
The Lambda function can receive directives from Alexa as JSON, process them, and then return a response with the expected JSON. Directives are JSON messages that contain instructions about performing specific actions, like getting metadata for a video. Currently, there is a JSON object that functions as a video content database embedded within the reference Lambda code.
To configure the Lambda function to interact with another existing database that you own, modify the database access class to query this database and return data structured in the same way as in the reference code. The rest of the Lambda code can remain unchanged as it responds dynamically to the contents returned by the database access layer.
By default, the reference Lambda uses the Gracenote catalog (named as 'ontv'). See Use your Own Catalog Name if you own a catalog that has already been ingested by Alexa, and want to use that catalog instead.
Features
The reference Lambda supports the following main features:
| Feature | By | Example |
|---|---|---|
| Search | Video id |
Search for Stranger Things Search for Psych Season 1 Search for Black Panther |
| Search | Actor Name |
Search for movies by Liam Neeson Search for movies by Jamie Foxx |
| Search | Genre |
Search for Comedy movies Search for Action movies Search for Adventure movies |
| Search | Multiple video metadata fields, such as Actor + Genre |
Search for Action movies by Liam Neeson Search for Comedy TV Series by Jennifer Aniston Note that on the search results page, you can also say something like: Select the second one Play number 1 |
| Quick Play | Video Name |
Watch Stranger Things Watch Psych Season 1 Episode 1 Watch Black Panther |
| Quick Play | Actor Name |
Watch movies by Liam Neeson Watch movies by Jamie Foxx |
| Quick Play | Genre |
Watch Comedy movies Watch Action movies Watch Adventure movies |
| Quick Play | Multiple video metadata fields, such as Actor + Genre |
Watch Action movies by Liam Neeson Watch Comedy TV Series by Jennifer Aniston |
| Channel Navigation | Tune to PBS Tune to NBC |
|
| Browse and List Selection | Explore different categories listed Explore additional categories under More Categories by saying: Select Highly Rated Select More Categories |
Note that the transport controls are specified by the web player included in the reference software.
Lambda Installation and Updates
Your Lambda needs to be hosted on AWS, which is handled by the CLI tool during the installation process. It also needs to be configured in the skill manifest, which is something that you might want to do in the developer portal. Typically, however, the infrastructure CLI tool included in the project automatically sets this up for you.
By using --deploy, the infrastructure CLI tool creates and deploys the Lambda function. This happens during the reference video skill setup.
Use --update --lambda to update and deploy the Lambda code during your development cycle. This significantly speeds up the development process.
For a manual Lambda installation process, see Set up Lambda Manually (Optional).
The Lambda must be configured in the video skill's manifest. The infrastructure CLI tool included in the project, handles that for you. However, if you choose a manual configuration, you must visit the Alexa developer console and follow the steps under Set up Lambda Manually (Optional).
Set Up Lambda Manually (Optional)
If you want to install your Lambda manually (rather than through the CLI tool), you must follow a different process:
- Navigate to the local
./lambdafolder of your project. - Run
npm run release. - Create an AWS Lambda function in the same region where you wish to deploy your video skill, following the steps mentioned here.
- Copy the compiled Lambda code from
./lambda/dist/lambdato the AWS Lambda function created in Step 3. -
In your Lambda execution role created in Step 3, add the following policy:
{ "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "s3:GetObject", "dynamodb:BatchGetItem", "dynamodb:BatchWriteItem", "dynamodb:PutItem", "dynamodb:DeleteItem", "dynamodb:GetItem", "dynamodb:Scan", "dynamodb:Query", "dynamodb:UpdateItem", "logs:CreateLogGroup", "logs:CreateLogStream", "logs:PutLogEvents" ], "Resource": ["*"] } ] } -
Create a DynamoDB database for your Lambda, to store data for pagination using the following specs:
"PaginationDatabase": { "Type" : "AWS::DynamoDB::Table", "Description": "Holds data for Pagination", "Properties" : { "TableName" : { "Fn::Sub": [ "${ProjectName}-pagination-table", { "ProjectName": { "Ref": "ProjectName" } } ] }, "AttributeDefinitions" : [ { "AttributeName" : "token", "AttributeType" : "S" } ], "KeySchema" : [ { "AttributeName" : "token", "KeyType" : "HASH" } ], "ProvisionedThroughput" : { "ReadCapacityUnits" : "5", "WriteCapacityUnits" : "5" } } }
Next Steps
See Lambda Customization.
Last updated: Oct 29, 2020