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Slack Notify Action

A composite GitHub Action that wraps the official slackapi/slack-github-action to send notifications to Slack channels.

Prerequisites

1. Create a Slack App

Go to https://api.slack.com/apps
Click "Create New App" → "From scratch"
Name your app (e.g., "GitHub Notifications") and select your workspace
Click "Create App"

2. Configure Bot Permissions

Navigate to "OAuth & Permissions" in the left sidebar
Scroll to "Scopes" → "Bot Token Scopes"
Add the following scopes:
- chat:write - Send messages
- chat:write.public - Send messages to public channels without joining
- channels:read - (Optional) List public channels
Click "Install to Workspace" at the top
Copy the "Bot User OAuth Token" (starts with xoxb-)

3. Get Channel ID

Method 1: From Slack UI

Open the Slack channel
Click the channel name at the top
Scroll down to find the Channel ID (e.g., C1234567890)

Method 2: Right-click method

Right-click on the channel name
Select "Copy Link"
The URL contains the channel ID: https://workspace.slack.com/archives/C1234567890

4. Add Token to GitHub Secrets

Go to your GitHub repository
Navigate to Settings → Secrets and variables → Actions
Click "New repository secret"
Name: SLACK_BOT_TOKEN
Value: Your Bot User OAuth Token (from step 2)
Click "Add secret"

Quick Start

Basic Text Message

name: Slack Notification

on:
  push:
    branches: [main]

jobs:
  notify:
    runs-on: ubuntu-latest
    steps:
      - uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
        with:
          slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
          channel-id: C1234567890
          message: "✅ Build completed successfully for ${{ github.repository }}!"

How It Works

The action automatically injects the channel field into your payloads, so you don't need to include it manually:

Simple messages: Just provide message input - channel is added automatically
Custom payloads: Provide JSON in payload input - channel is merged automatically

Example: You provide this:

{
  "blocks": [
    { "type": "section", "text": { "type": "mrkdwn", "text": "Hello!" } }
  ]
}

The action automatically merges it to:

{
  "channel": "C1234567890",
  "blocks": [
    { "type": "section", "text": { "type": "mrkdwn", "text": "Hello!" } }
  ]
}

Inputs

Input	Description	Required	Default
`slack-bot-token`	Slack Bot User OAuth Token (xoxb-...)	Yes	-
`channel-id`	Slack channel ID (e.g., C1234567890)	Yes	-
`message`	Simple text message (supports Slack mrkdwn)	No	`''`
`payload`	Custom JSON payload for advanced formatting	No	`''`
`method`	Slack API method to call	No	`chat.postMessage`
`errors`	Whether to fail the step on errors	No	`true`

Outputs

Output	Description
`time`	Time the message was sent
`thread_ts`	Thread timestamp (for threaded replies)
`ts`	Message timestamp

Examples

Example 1: Deployment Success Notification

name: Deploy and Notify

on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Deploy Application
        run: ./deploy.sh

      - name: Notify Success
        if: success()
        uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
        with:
          slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
          channel-id: C1234567890
          message: |
            🚀 *Deployment Successful*

            *Repository:* ${{ github.repository }}
            *Branch:* ${{ github.ref_name }}
            *Commit:* ${{ github.sha }}
            *Author:* ${{ github.actor }}

            <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|View Workflow>

Example 2: Failure Notification

- name: Notify Failure
  if: failure()
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C1234567890
    message: |
      ❌ *Build Failed*

      *Repository:* ${{ github.repository }}
      *Branch:* ${{ github.ref_name }}
      *Triggered by:* ${{ github.actor }}

      <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|View Logs>

Example 3: Pull Request Notification

name: PR Notifications

on:
  pull_request:
    types: [opened, closed]

jobs:
  notify:
    runs-on: ubuntu-latest
    steps:
      - name: PR Opened
        if: github.event.action == 'opened'
        uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
        with:
          slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
          channel-id: C1234567890
          message: |
            🔔 *New Pull Request*

            *Title:* ${{ github.event.pull_request.title }}
            *Author:* ${{ github.event.pull_request.user.login }}
            *Repository:* ${{ github.repository }}

            <${{ github.event.pull_request.html_url }}|View Pull Request>

      - name: PR Merged
        if: github.event.pull_request.merged == true
        uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
        with:
          slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
          channel-id: C1234567890
          message: |
            ✅ *Pull Request Merged*

            *Title:* ${{ github.event.pull_request.title }}
            *Merged by:* ${{ github.actor }}
            *Branch:* ${{ github.event.pull_request.head.ref }} → ${{ github.event.pull_request.base.ref }}

Example 4: Advanced Block Kit Message

- name: Send Rich Message
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C1234567890
    payload: |
      {
        "blocks": [
          {
            "type": "header",
            "text": {
              "type": "plain_text",
              "text": "🎉 Release Published"
            }
          },
          {
            "type": "section",
            "fields": [
              {
                "type": "mrkdwn",
                "text": "*Version:*\nv1.2.3"
              },
              {
                "type": "mrkdwn",
                "text": "*Repository:*\n${{ github.repository }}"
              },
              {
                "type": "mrkdwn",
                "text": "*Released by:*\n${{ github.actor }}"
              },
              {
                "type": "mrkdwn",
                "text": "*Date:*\n$(date -u +'%Y-%m-%d %H:%M:%S UTC')"
              }
            ]
          },
          {
            "type": "actions",
            "elements": [
              {
                "type": "button",
                "text": {
                  "type": "plain_text",
                  "text": "View Release"
                },
                "url": "${{ github.server_url }}/${{ github.repository }}/releases/tag/v1.2.3"
              }
            ]
          }
        ]
      }

Example 5: Conditional Notification (Success or Failure)

- name: Send Build Status
  if: always()
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C1234567890
    message: |
      ${{ job.status == 'success' && '✅' || '❌' }} *Build ${{ job.status }}*

      *Repository:* ${{ github.repository }}
      *Workflow:* ${{ github.workflow }}
      *Status:* ${{ job.status }}

      <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|View Details>

Example 6: Reply to Thread

- name: Initial Message
  id: initial-message
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C1234567890
    message: "🔄 Deployment started..."

- name: Deploy
  run: ./deploy.sh

- name: Thread Reply
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C1234567890
    payload: |
      {
        "thread_ts": "${{ steps.initial-message.outputs.ts }}",
        "text": "✅ Deployment completed successfully!"
      }

Example 7: Multiple Channels

- name: Notify Multiple Channels
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C1234567890
    message: "📢 Important update!"

- name: Notify Dev Channel
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C0987654321
    message: "👩‍💻 Dev team: deployment completed"

Example 8: Schedule-Based Notifications

name: Daily Report

on:
  schedule:
    - cron: "0 9 * * MON-FRI" # 9 AM UTC, Monday-Friday

jobs:
  daily-report:
    runs-on: ubuntu-latest
    steps:
      - name: Generate Report
        id: report
        run: |
          # Generate your report data
          echo "report_data=Sample report data" >> $GITHUB_OUTPUT

      - name: Send Daily Report
        uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
        with:
          slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
          channel-id: C1234567890
          message: |
            📊 *Daily Report* - $(date +'%Y-%m-%d')

            ${{ steps.report.outputs.report_data }}

Example 9: Using Different API Methods

# Update a message
- name: Update Message
  uses: NVIDIA/dsx-github-actions/.github/actions/slack-notify@main
  with:
    slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}
    channel-id: C1234567890
    method: chat.update
    payload: |
      {
        "ts": "${{ steps.previous-message.outputs.ts }}",
        "text": "Updated message content"
      }

Message Formatting

Slack Mrkdwn Syntax

*bold text*
_italic text_
~strikethrough~
`code`
```code block```
> quote
• bullet

Links

<https://example.com|Link Text>
<@U1234567890> - Mention user
<!channel> - Mention channel
<!here> - Mention active users

Emojis

:smile: :rocket: :tada: :white_check_mark: :x:

Block Kit Builder

Use the Slack Block Kit Builder to design rich interactive messages.

Troubleshooting

Issue: "not_in_channel" Error

Solution: Either:

Add the bot to the channel (invite it like a regular user), OR
Add the chat:write.public scope to post to public channels without joining

Issue: "channel_not_found" Error

Solution:

Verify the channel ID is correct (not the channel name)
Ensure the bot has access to the channel
For private channels, the bot must be invited

Issue: Token Not Working

Solution:

Ensure you're using the Bot User OAuth Token (starts with xoxb-)
Verify the token is added to GitHub Secrets correctly
Check that required scopes are added to the bot

Issue: Message Not Formatted

Solution:

For simple formatting, use the message input with mrkdwn syntax
For advanced formatting, use the payload input with Block Kit JSON
Don't mix message and payload - payload takes precedence

Issue: Rate Limiting

Solution:

Slack has rate limits on API calls
Use the retries input to handle temporary failures
Consider batching notifications or using webhooks for high-volume scenarios

Best Practices

1. Use GitHub Secrets for Tokens

Always store Slack tokens in GitHub Secrets, never hardcode them:

slack-bot-token: ${{ secrets.SLACK_BOT_TOKEN }}

2. Use Channel IDs, Not Names

Always use channel IDs (e.g., C1234567890) instead of names (e.g., #general).

3. Add Context to Messages

Include relevant information in your notifications:

message: |
  *Repository:* ${{ github.repository }}
  *Branch:* ${{ github.ref_name }}
  *Commit:* ${{ github.sha }}
  *Author:* ${{ github.actor }}

4. Use Conditional Notifications

Only send notifications when necessary:

if: success()  # Only on success
if: failure()  # Only on failure
if: always()   # Always send

5. Handle Errors Gracefully

For non-critical notifications, set errors: 'false':

with:
  errors: "false" # Don't fail workflow if notification fails

6. Use Threads for Related Messages

Keep related messages organized using threads:

thread_ts: ${{ steps.initial-message.outputs.ts }}

7. Design for Mobile

Keep messages concise and scannable - many users will read them on mobile devices.

Security Considerations

Token Storage: Always use GitHub Secrets for Slack tokens
Token Scope: Use the minimum required scopes for your bot
Channel Access: Only give bot access to channels it needs
Sensitive Data: Avoid including secrets or sensitive data in messages
Token Rotation: Periodically rotate your Slack bot tokens

Slack API Methods

Besides chat.postMessage, you can use other methods:

chat.update - Update an existing message
chat.delete - Delete a message
chat.scheduleMessage - Schedule a message
files.upload - Upload a file
reactions.add - Add a reaction to a message

Refer to the Slack API documentation for all available methods.

References

License

Licensed under the Apache License, Version 2.0.

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parent directory

README.md

Slack Notify Action

Prerequisites

1. Create a Slack App

2. Configure Bot Permissions

3. Get Channel ID

4. Add Token to GitHub Secrets

Quick Start

Basic Text Message

How It Works

Inputs

Outputs

Examples

Example 1: Deployment Success Notification

Example 2: Failure Notification

Example 3: Pull Request Notification

Example 4: Advanced Block Kit Message

Example 5: Conditional Notification (Success or Failure)

Example 6: Reply to Thread

Example 7: Multiple Channels

Example 8: Schedule-Based Notifications

Example 9: Using Different API Methods

Message Formatting

Slack Mrkdwn Syntax

Links

Emojis

Block Kit Builder

Troubleshooting

Issue: "not_in_channel" Error

Issue: "channel_not_found" Error

Issue: Token Not Working

Issue: Message Not Formatted

Issue: Rate Limiting

Best Practices

1. Use GitHub Secrets for Tokens

2. Use Channel IDs, Not Names

3. Add Context to Messages

4. Use Conditional Notifications

5. Handle Errors Gracefully

6. Use Threads for Related Messages

7. Design for Mobile

Security Considerations

Slack API Methods

References

License