quotient-quotes

A simple quote bot for Slack built with AWS Lambda and DynamoDB.

Lambda Function

lambda/index.js has been tested with Node.js 10.x and 12.x.

1. Create a function from scratch.
2. Choose a Node.js runtime.
3. Create a new role from template with any name.
4. Choose the "Simple Microservice permissions" Policy template.

It will be given permission to:

1. Write CloudWatch logs. Example:
   • arn:aws:logs:us-east-1:<YOUR ACCOUNT ID>:* => Allow: logs:CreateLogGroup
   • arn:aws:logs:us-east-1:<YOUR ACCOUNT ID>:log-group:/aws/lambda/quotient:* => Allow: logs:CreateLogStream, Allow: logs:PutLogEvents
2. Read/write to DynamoDB. Example:
   • arn:aws:dynamodb:us-east-1:<YOUR ACCOUNT ID>:table/quotes => Allow: dynamodb:DeleteItem, Allow: dynamodb:GetItem, Allow: dynamodb:PutItem, Allow: dynamodb:Scan, Allow: dynamodb:UpdateItem

Designer

1. Under Designer > Add Triggers, choose API Gateway.
2. Set Configure triggers > API to Create a new API
3. Set Configure triggers > API name to something that matches your function.
4. Set Configure triggers > Deployment stage to e.g. "dev".
5. Set Configure triggers > Security to Open.

Function code

Paste the contents of index.js into the editor.

Environment Variables

• APP_TOKEN - Slack verification token.
• COMMANDS_TABLENAME - name of the DynamoDB table that stores the command mappings.
• QUOTES_TABLENAME - name of the DynamoDB table that stores quotes.
• IS_DEBUG - true/false - writes debug output to CloudWatch log.

DynamoDB

The Lambda function depends on two DynamoDB tables:

• commands maps a Slack slash-command to a category. The command field is the primary key. Example item:

{
    "command": "/chucknorris",
    "category": "ChuckNorris"
}

• quotes stores all the quotes. The uuid field is the primary key. Example item:

{
    "uuid": "81f05bc0-615e-4a88-88a8-66e7144fc8e5",
    "category": "ChuckNorris",
    "quote": "Chuck Norris invented Kentucky Fried Chicken's famous secret recipe, with eleven herbs and spices. But nobody ever mentions the twelfth ingredient: Fear."
}

API Gateway

Creating the API Gateway trigger should have setup the resource and stage that you defined.

Deploy the resource.

Slack

Create a Slack bot.

Make a Bot user, giving it any name. Turn on "Always Show My Bot as Online".

For the Lambda function environment variable APP_TOKEN, use the value of Slack > [Your Bot] > Basic Information > App Credentials > Verification Token.

Create slash commands that point to the desired API Gateway stage. The Request URL can be found in API Gateway > [Your API] Stages > [Stage] > Invoke URL.