votebot

What is this?

The world will love bots until they take over. Until then, we'll keep making them! votebot is a bot for Slack which allows you to ... well, vote! votebot is built using Python on AWS Lambda and driven by the Outgoing Webhook integration in Slack.

Under the hood

The options for votebot are stored in a DynamoDB table for persistence between Lambda function runs. The hash key is titled selection, and a second attribute called options stores each votable option. They are stored as comma-separated values. There is a another attribute, icon_emoji, which allows you to customize the reaction emoji that users can click on. For each option, the following convention is used:

Title / description1 / description2 / description3,

An example of what your DynamoDB table might look like is as follows:

Hash key	options attribute	icon_emoji attribute
pistarro	Pepperoni / tomato sauce / pepperoni / mozzarella / basil, Florintina / spinach / ricotta / artichoke / roasted pepper / parmesan v.	pizza

Dependencies

Python libraries

• boto3
• slacker

AWS services

• Lambda
• API Gateway
• DynamoDB
• IAM

Slack services

• Outgoing Webhooks
• Bot integration

Example

wayne: votebot open pistarro

[11:07] votebotBOT: @here wayne has opened voting for `pistarro`. Please vote by clicking on an emoji! To close voting, please enter `votebot close pistarro-10/15/2015-15:07:13`

[11:07] votebotBOT: Margherita tomato sauce / mozzarella / basil v.
:pizza:2  

[11:07] votebotBOT: Bianca garlic / caramelized onions / ricotta / mozzarella / pecorino v.
:pizza:4  

[11:07] votebotBOT: Capricciosa tomato sauce / mushroom / artichoke / speck / mozzarella
:pizza:1  

[11:07] votebotBOT: Versace tomato sauce / mozzarella / prosciutto / arugula
:pizza:1  

[11:07] votebotBOT: Pepperoni tomato sauce / pepperoni / mozzarella / basil
:pizza:3 :gopherhead:2  

...

wayne: votebot close pistarro-10/15/2015-15:07:13

[11:20] votebotBOT: @here wayne closed voting for pistarro-10/15/2015-15:07:13! Results:
3 vote(s) each for Bianca, Pepperoni, Florintina
2 vote(s) each for Diavola, Blu Fico, Salsiccia, Carciofo 
1 vote(s) each for Margherita, Napoletana, Fumo Verde, Polpettine, Bresaola, Marinara (no cheese)  
0 vote(s) each for Capricciosa, Versace, Funghi, Donatello, Maiale, Ananas, Verdure 
Total votes: 23

Setup

tl;dr

1. Clone this votebot repo
2. Set up an Outgoing Webhook and bot integration in Slack
3. Place your channel token in a file named SLACK_CHANNEL_TOKEN at this level in the directory
4. Place your bot authorization token in a file named SLACK_BOT_API_TOKEN at this level in the directory
5. Set up IAM permissions for Lambda
6. Set up DynamoDB
7. Populate the vote-options table with some things you want to vote on (remember, options are comma-separated)
8. Zip the contents of the votebot directory, NOT the directory itself
9. Create a Lambda function by uploading the zip file to Lambda
10. Create an API Gateway entry pointing to your Lambda function, ensuring you include a mapping template
11. Once deployed, copy the POST URL of your API Gateway entry and configure your Outgoing Webhook with it
12. Vote!

The longer version

DynamoDB

There are two DynamoDB tables votebot uses. One is called vote-options and the other is vote-open. The vote storage tables use 1 provisioned read and 1 provisioned write throughput, along with a small amount of actual storage. This falls well below the free tier for DDB (25 reads and 25 writes per second). If you are already a heavy DDB user and exceed the free tier, the tables will cost about ~$1 per month.

To set up DynamoDB, run setup_ddb.sh. For now, the table must be manually populated with options.

IAM

The IAM role must have a trust relationship for Lambda which meets the following:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Principal": {
                "Service": "lambda.amazonaws.com"
            },
            "Action": "sts:AssumeRole"
        }
    ]
}

And the policy is expressed as:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "dynamodb:*"
            ],
            "Resource": [
                "arn:aws:dynamodb:us-west-2:*:table/vote-options",
                "arn:aws:dynamodb:us-west-2:*:table/vote-open"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogGroup",
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": "arn:aws:logs:*:*:*"
        }
    ]
}

To set up IAM, run setup_iam.sh. The role will be named votebot.

More information

See the Fugue blog for a walkthrough of setup, packaging, and deployment!