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Post-mortem Timeline Generator - Export reacted messages from Slack via a DM to a Slackbot.
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Post-mortem Timeline Generator

Mark messages in a public slack channel with a reaction emoji such as :small_blue_diamond: and export them to a file sent via DM.

Trigger with: /timeline :small_blue_diamond:

Here's what it looks like when used:


and here's the backend:


To deploy:

Set up pre-requisites

  • Python3
  • pip install --user awscli aws-sam-cli pipenv
  • Valid AWS credentials
  • Slack permission to create a Slack application.

Create a Slack App

  • Start here: and create an App.

  • add a Bot user, and hit Install App. Customise the name and preference :)

  • Note down the App and Bot OAuth tokens, and the Signing Secret to set as variables later.

  • In OAuth and Permissions, add these:

    • channels:history (to parse the channel’s messages for reactions)
    • chat:write:bot (to message the user as the bot)
    • chat:write:user (to write ephemeral user-only messages to the user)
    • im:read (to handle the slash command and fail gracefully in dm’s)
    • files:write:user (to send the file)
    • users:read (to read the user directory and work out username to user id to make the output legible).
  • You'll need your API Gateway URL to enable the slash command: we'll come back to this.

Set AWS parameters

Create S3 bucket if required:

aws s3 mb s3://deploy-timeline-<uniquename>


BUCKET='deploy-timeline' # Bucket to hold .yml in AWS for SAM
STACK_NAME='slack-timeline-tool' # CF stack name
BOT_TOKEN=<slack bot token> # From slack app
SLACK_TOKEN=<slack app token> # From slack app
SIGNING_SECRET=<slack signing secret> # From slack app


From this repo's directory, deploy deploy.yml using SAM CLI (a Cloudformation transform) to create the AWS resources required. The below will upload requirements to S3, create a new .yml, push to AWS then clean up after itself.


sam package --template-file deploy.yml \ 
--s3-bucket $BUCKET --output-template-file packaged.yml --region eu-west-1
sam deploy --template-file packaged.yml \
 --stack-name $STACK_NAME --capabilities CAPABILITY_NAMED_IAM \
 --region eu-west-1 --parameter-overrides SigningSecret=$SIGNING_SECRET \
SlackBotToken=$BOT_TOKEN SlackAppToken=$SLACK_TOKEN

You can now create your Slack App's slash command (I went with /timeline) and add the created API Gateway's URL to it! 🎉

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