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Sending data via a webhook to start a Slack workflow

This technique requires a Slack paid plan to use Workflow Builder.

This technique sends data to Slack using a webhook to start a workflow created using Slack Workflow Builder.

Setup​

Start in Slack to create a Slack workflow:

  1. Create a Slack workflow that starts from a webhook.
  2. Copy the webhook URL and add it as a repository secret called SLACK_WEBHOOK_URL.
  3. Add this Action as a step to your GitHub workflow and provide an input payload to send to the webhook.
  4. Configure your Slack workflow to use the payload variables sent from the GitHub Action. You can then update the steps of the Slack workflow to use these values in creative and clever ways.

The webhook URL will resemble something like so:

https://hooks.slack.com/triggers/T0123456789/3141592653589/c6e6c0d868b3054ca0f4611a5dbadaf

Usage​

Update the input payloads sent from this GitHub Action to your Slack workflow using the following options:

Sending values from the default GitHub event context​

In the example below, the default GitHub event context and event payload associated with the job that started the GitHub workflow are sent to the provided webhook URL:

- name: Send GitHub Action data to a Slack workflow
  uses: slackapi/slack-github-action@v2.0.0
  with:
    payload-delimiter: "_"
    webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
    webhook-type: webhook-trigger

Accessing variables sent to Workflow Builder with a webhook require that the payload variables are flattened with stringified values. Nested variables in the provided payload can be both flattened and also stringified with the payload-delimiter option or changed with other configurations to match this format expected from Workflow Builder.

Providing parsed payload information as strings​

Provided input values for payload information are sent to the webhook URL after the job is started:

- name: Send custom event details to a Slack workflow
  uses: slackapi/slack-github-action@v2.0.0
  with:
    webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
    webhook-type: webhook-trigger
    payload: |
      status: "${{ job.status }}"
      option: "false"

Gathering details of the payload from a saved file​

Input values for the payload to be sent can also be provided in a file, either in JSON or YAML format:

- name: Send a saved artifact to a Slack workflow
  uses: slackapi/slack-github-action@v2.0.0
  with:
    payload-file-path: "./artifacts.json"
    webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
    webhook-type: webhook-trigger

Example workflows​