Did-you-hear Publisher Slack App

What is it?

This project is the backend of a Slack bot designed to publish daily news and regular summaries about news worthy topics. We use it internally to publish regular updates about AWS services and publications.

The serverless infrastructure necessary is deployed to AWS using AWS CDK.

Background

This tool was built to make gathering and sharing AWS related news on our company Slack channels.

The manual process before we had this tool required to:

• take note of any interesting news or articles we found along our day
• once a day go on Slack and publish a daily message listing those news/articles on a dedicated channel
• once a week gather all the daily updates in the form of a summary on the main tech channel

This was a very time consuming and error prone process, especially when it came to gathering the content and formatting the Slack messages.

Components and architecture

This application is composed of 3 main components, which compose the overall architecture:

UI Frontend

The first component is a simple React-based UI, in which you can enter the content. The syntax used for Urls and other special formatting is the Slack API syntax.

UI Backend

The second component is composed of a CloudFront distribution connected with a Lambda via Lambda URL, which saves the content to a DynamoDB table. The URL is protected via IAM authentication, enforced in the CloudFront distribution via Lambda@Edge.

Publishers

The last component is made up of two lambdas, one for the daily publication and one for the regular/weekly publication (the regularity is configurable). Both Lambdas regularly check in the DynamoDB table what news need to be published and record the succesful publication to avoid duplications.

Deployment

Currently the deployment is done from local via the CLI, with the possibility to deploy either to a Development or Production environment.

AWS note: If you use profiles to connect to AWS, you will need to execute AWS_PROFILE={your profile name} before continuing.

Setup

The following environment variables must exist:

export DEV_ACCOUNT=12345678       # AWS development account ID
export DEV_REGION=eu-central-1    # AWS development region
export PROD_ACCOUNT=12345678      # AWS production account ID
export PROD_REGION=eu-central-1   # AWS production region

export SLACK_DAILY_URL=https://hooks.slack.com/services/sfsfsdfsdfs  # Slack webhook URL for the daily publication 
export SLACK_SUMMARY_URL=https://hooks.slack.com/services/sdfsdfafd  # Slack webhook URL for the summary publication

The Slack URL will be read by the backend Lambdas in the SSM Parameter Store. You can create the necessary secrets by using the following commands:

aws ssm put-parameter --name /Publisher/SlackDailyUrl --value $SLACK_DAILY_URL --type SecureString
aws ssm put-parameter --name /Publisher/SlackSummaryUrl --value $SLACK_SUMMARY_URL --type SecureString

Deploy via CDK

Install all dependencies (this also installs dependencies of all sub-folders):

npm i

In a new account, you will first need to bootstrap CDK:

cd cdk

npx cdk bootstrap -c env=dev
or
npx cdk bootstrap -c env=prod

Then run the cdk deployment, from the root of the project:

npm run deploy -- -c env=dev
# or
npm run deploy -- -c env=prod

Once deployed, you can find the URL of the UI in the outputs of the CDK command.

Security

The last step is to create a user in the Cognito pool. You can do that in the AWS console.

Development

Tests

To run the tests, use:

npm run test

Improvements planned

• CI/CD pipelines
• integration tests
• e2e tests
• more options for configuration