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Setup

Get Slack notifications working with your Nextflow pipeline in minutes.

Prerequisites

  • Nextflow v25.04.0 or later
  • A Slack workspace where you have permission to add apps

1. Create a Slack App

  1. Go to Slack API Apps
  2. Click "Create New App" → "From scratch"
  3. Name your app (e.g., "Nextflow Notifications"), select your workspace, and click "Create App"

2. Configure Slack Credentials

nf-slack supports two authentication methods. Bot User is recommended — it supports threading, emoji reactions, and file uploads.

Add permissions:

  1. Navigate to "OAuth & Permissions" in the sidebar
  2. Under "Bot Token Scopes", add:
    • chat:write — Send messages
    • chat:write.public — Post to channels without joining (optional)
    • reactions:write — Add emoji reactions (optional — required for emoji reactions)
    • files:write — Upload files (optional — required for file uploads)

Install and copy token:

  1. Scroll to the top of "OAuth & Permissions"
  2. Click "Install to Workspace" → "Allow"
  3. Copy the Bot User OAuth Token (starts with xoxb-)

Keep your token secret

Never commit tokens to version control. See storing credentials securely below.

Test it:

export SLACK_BOT_TOKEN='xoxb-your-token'
curl -X POST https://slack.com/api/chat.postMessage \
  -H "Authorization: Bearer $SLACK_BOT_TOKEN" \
  -H "Content-type: application/json" \
  --data '{"channel":"general","text":"Test from nf-slack"}'

Enable webhooks:

  1. Navigate to "Incoming Webhooks" in the sidebar
  2. Toggle "On"
  3. Click "Add New Webhook to Workspace"
  4. Select the target channel → "Allow"
  5. Copy the webhook URL (starts with https://hooks.slack.com/services/...)

Keep your webhook URL secret

Never commit webhook URLs to version control. See storing credentials securely below.

Webhook limitations

Webhooks don't support threading, emoji reactions, or file uploads. Use a Bot User for these features.

Test it:

export SLACK_WEBHOOK_URL='https://hooks.slack.com/services/YOUR/WEBHOOK/URL'
curl -X POST -H 'Content-type: application/json' \
  --data '{"text":"Test from nf-slack"}' \
  $SLACK_WEBHOOK_URL

3. Store Credentials Securely

# Bot
export SLACK_BOT_TOKEN='xoxb-your-token'

# Webhook
export SLACK_WEBHOOK_URL='https://hooks.slack.com/services/YOUR/WEBHOOK/URL'

# Bot
nextflow secrets set SLACK_BOT_TOKEN 'xoxb-your-token'

# Webhook
nextflow secrets set SLACK_WEBHOOK_URL 'https://hooks.slack.com/services/YOUR/WEBHOOK/URL'

4. Add the Plugin to Your Pipeline

Add nf-slack to your nextflow.config:

plugins {
    id 'nf-slack@0.5.1'
}

Then add the Slack configuration block:

slack {
    bot {
        token = System.getenv('SLACK_BOT_TOKEN')
        channel = 'general'
    }
}

slack {
    webhook {
        url = "$SLACK_WEBHOOK_URL"
    }
}

5. Run Your Pipeline

nextflow run main.nf

You'll receive Slack notifications when your pipeline starts, completes, and fails.

Default notifications

Next Steps

  • Usage Guide — Customize notifications, enable threading, send messages from code
  • Examples — Copy-paste configurations for common scenarios
  • API Reference — Complete configuration reference

Learn More