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Sending data using a Slack API method

A bot token or user token or token of some other kind must be used to call one of the Slack API methods with this technique.

Setup​

Different Slack API methods require different scopes, but setup should be similar for all methods:

  1. Create a Slack app for your workspace or use an existing app.
  2. Depending on the Slack API method you wish to call, add the required scopes to your app under the OAuth & Permissions page on app settings.
  3. Install the app to your workspace using the Install App page.
  4. Once your app is installed to a workspace, a new token with your app's specified scopes will be minted for that workspace. It is worth noting that tokens are only valid for a single workspace! Find the token on the OAuth & Permissions page.
  5. Add the token as a repository secret called SLACK_BOT_TOKEN or something similar and memorable.
  6. Add this Action as a step to your GitHub workflow and provide an input payload to send to the method.

Methods that require an app configuration token should gather this token from the app configuration token settings instead of from a specific app since this token is associated with the workspace.

Usage​

Choosing inputs for these steps is left as an exercise for the actioneer since each of the Slack API methods requires certain values and specific parameters, but these snippets might be helpful when starting.

Posting a message with text​

Posting a message with the chat.postMessage method can be achieved by adding this step to a job in your GitHub workflow and inviting the bot associated with your app to the channel for posting:

- name: Post text to a Slack channel
  uses: slackapi/slack-github-action@v2.0.0
  with:
    method: chat.postMessage
    token: ${{ secrets.SLACK_BOT_TOKEN }}
    payload: |
      channel: ${{ secrets.SLACK_CHANNEL_ID }}
      text: "howdy <@channel>!"

Posting a message with blocks​

More complex message layouts, such as messages made with Block Kit blocks, can also be sent with one of the Slack API methods:

- name: Post blocks to a Slack channel
  uses: slackapi/slack-github-action@v2.0.0
  with:
    method: chat.postMessage
    token: ${{ secrets.SLACK_BOT_TOKEN }}
    payload: |
      channel: ${{ secrets.SLACK_CHANNEL_ID }}
      text: "GitHub Action build result: ${{ job.status }}\n${{ github.event.pull_request.html_url || github.event.head_commit.url }}"
      blocks:
        - type: "section"
          text:
            type: "mrkdwn"
            text: "GitHub Action build result: ${{ job.status }}\n${{ github.event.pull_request.html_url || github.event.head_commit.url }}"

Updating a message​

Updating a message after it's posted can be done with the chat.update method and chaining multiple steps together using outputs from past steps as inputs to current ones:

- name: Initiate the deployment launch sequence
  id: launch_sequence
  uses: slackapi/slack-github-action@v2.0.0
  with:
    method: chat.postMessage
    token: ${{ secrets.SLACK_BOT_TOKEN }}
    payload: |
      channel: ${{ secrets.SLACK_CHANNEL_ID }}
      text: "Deployment started :eyes:"
      attachments:
        - color: "dbab09"
          fields:
            - title: "Status"
              short: true
              value: "In Progress"
- name: Countdown until launch
  run: sleep 10
- name: Update the original message with success
  uses: slackapi/slack-github-action@v2.0.0
  with:
    method: chat.update
    token: ${{ secrets.SLACK_BOT_TOKEN }}
    payload: |
      channel: ${{ secrets.SLACK_CHANNEL_ID }}
      ts: "${{ steps.launch_sequence.outputs.ts }}"
      text: "Deployment finished! :rocket:"
      attachments:
        - color: "28a745"
          fields:
            - title: "Status"
              short: true
              value: "Completed"

Replying to a message​

Posting threaded replies to a message from a past job can be done by including the thread_ts attribute of the parent message in the payload:

- name: Initiate a deployment
  uses: slackapi/slack-github-action@v2.0.0
  id: deployment_message
  with:
    method: chat.postMessage
    token: ${{ secrets.SLACK_BOT_TOKEN }}
    payload: |
      channel: ${{ secrets.SLACK_CHANNEL_ID }}
      text: "Deployment started :eyes:"
- name: Conclude the deployment
  uses: slackapi/slack-github-action@v2.0.0
  with:
    method: chat.postMessage
    token: ${{ secrets.SLACK_BOT_TOKEN }}
    payload: |
      channel: ${{ secrets.SLACK_CHANNEL_ID }}
      thread_ts: "${{ steps.deployment_message.outputs.ts }}"
      text: "Deployment finished! :rocket:"

Uploading a file​

Calling a Slack API method with @slack/web-api makes uploading a file just another API call with all of the convenience of the files.uploadV2 method:

- name: Share a file to that channel
  uses: slackapi/slack-github-action@v2.0.0
  with:
    method: files.uploadV2
    token: ${{ secrets.SLACK_BOT_TOKEN }}
    payload: |
      channel_id: ${{ secrets.SLACK_CHANNEL_ID }}
      initial_comment: "the results are in!"
      file: "./path/to/results.out"
      filename: "results-${{ github.sha }}.out"

Example workflows​