slack-github-action/example-workflows/Technique_2_Slack_API_Method/invite.yml

# yaml-language-server: $schema=https://json.schemastore.org/github-workflow.json

name: Invite a usergroup to channel
on:
  issues:
    types:
      - labeled
jobs:
  run:
    name: Respond to reports of a new problem
    runs-on: ubuntu-latest
    if: ${{ github.event.label.name == 'bug' }}
    steps:
      - name: Create a new Slack channel for communications
        id: conversation
        uses: slackapi/[email protected]
        with:
          errors: true
          method: conversations.create # https://docs.slack.dev/reference/methods/conversations.create/
          token: ${{ secrets.SLACK_BOT_TOKEN }}
          payload: |
            name: issue-${{ github.event.issue.number }}

      - name: Send the issue link into the Slack channel
        uses: slackapi/[email protected]
        with:
          errors: true
          method: chat.postMessage # https://docs.slack.dev/reference/methods/chat.postMessage/
          token: ${{ secrets.SLACK_BOT_TOKEN }}
          payload: |
            channel: ${{ steps.conversation.outputs.channel_id }}
            text: "An issue was opened <!date^${{ steps.conversation.outputs.time }}^{date_num} at {time_secs}|just now>: ${{ github.event.issue.html_url }}"

      - name: Gather information of those to add
        id: members
        uses: slackapi/[email protected]
        with:
          errors: true
          method: usergroups.users.list # https://docs.slack.dev/reference/methods/usergroups.users.list/
          token: ${{ secrets.SLACK_BOT_TOKEN }}
          payload: |
            usergroup: ${{ secrets.SLACK_USERGROUP_ID }}

      - name: Combine the list of usergroup users
        run: |
          SLACK_USERGROUP_USER_IDS=$(echo '${{ steps.members.outputs.response }}' | jq -r '.users | join(",")' )
          echo "SLACK_USERGROUP_USER_IDS=$SLACK_USERGROUP_USER_IDS" >> $GITHUB_ENV

      - name: Add the usergroup to the channel
        uses: slackapi/[email protected]
        with:
          errors: true
          method: conversations.invite # https://docs.slack.dev/reference/methods/conversations.invite/
          token: ${{ secrets.SLACK_BOT_TOKEN }}
          payload: |
            channel: ${{ steps.conversation.outputs.channel_id }}
            users: ${{ env.SLACK_USERGROUP_USER_IDS }}