Notifier

The notification feature is a Dewy component that automatically communicates deployment status to teams. Various events such as success, failure, and hook execution results can be notified via Slack and email.

Supported Notification Methods

Dewy supports the following notification methods:

• Slack (slack://): Notifications to Slack channels
• Mail (smtp://): Email notifications via SMTP

Notification Timing

Dewy sends notifications at the following times:

• Startup: Dewy service start
• Download completion: New artifact download
• Deploy success: Application startup/restart success
• Error occurrence: Various error occurrences
• Hook execution: Before/After hook execution results
• Shutdown: Dewy service shutdown

Quiet Mode

Adding quiet=true to the notifier URL suppresses verbose notifications (startup, download, successful hooks) while still delivering important ones (deploy success, errors, hook failures).

dewy server --registry ghr://owner/repo \
  --notifier "slack://deployments?title=MyApp&quiet=true"

Slack Notifications

Basic configuration

# Basic format
slack://<channel-name>

# Example
dewy server --registry ghr://owner/repo \
  --notifier slack://deployments \
  -- /opt/myapp/current/myapp

Environment variables

# Slack Bot Token (required)
export SLACK_TOKEN=xoxb-xxxxxxxxxxxxxxxxxxxxx

Slack App Configuration

1. Create Slack App
   • Create app at https://api.slack.com/apps
2. Required permissions (Scopes)
   • chat:write: Post messages
   • chat:write.customize: Customize bot name and icon per message
3. Invite the Slack App to the notification channel
   • You must invite the app to the channel via Slack GUI before sending notifications
4. Get token
   • OAuth & Permissions → Bot User OAuth Token

Configuration with Options

# Notification with title
dewy server --registry ghr://owner/repo \
  --notifier "slack://deployments?title=MyApp"

# Notification with URL (link to repository, etc.)
dewy server --registry ghr://owner/repo \
  --notifier "slack://deployments?title=MyApp&url=https://github.com/owner/repo"

# Multiple options
dewy server --registry ghr://owner/repo \
  --notifier "slack://prod-deploy?title=MyApp&url=https://myapp.example.com"

Slack Thread Notifications

When deploying to multiple servers, deploy notifications can flood a Slack channel. Thread notifications group all notifications for the same version into a single Slack thread, keeping the main channel feed clean.

How it works:

1. Your CI system (e.g., GitHub Actions) posts a parent message to Slack and saves the message timestamp (ts) to a file named .slack-thread-ts inside the artifact
2. Dewy extracts the artifact, reads .slack-thread-ts, and sends all subsequent notifications as thread replies
3. Error notifications use reply_broadcast so they also appear in the main channel feed

Enable thread mode by adding thread=true to the notifier URL:

dewy server --registry ghr://owner/repo \
  --notifier "slack://deploy-notify?title=MyApp&url=https://github.com/owner/repo&thread=true" \
  -- /opt/app/current/app

CI-side setup (GitHub Actions + GoReleaser example):

In your GitHub Actions workflow, post the Slack parent message before running GoReleaser. Then configure GoReleaser to include the .slack-thread-ts file in the archive.

.github/workflows/release.yml:

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

      - name: Post Slack parent message
        if: startsWith(github.ref, 'refs/tags/')
        env:
          SLACK_TOKEN: ${{ secrets.SLACK_TOKEN }}
          SLACK_CHANNEL: deploy-notify
        run: |
          TAG="${GITHUB_REF#refs/tags/}"
          TS=$(curl -s -X POST https://slack.com/api/chat.postMessage \
            -H "Authorization: Bearer $SLACK_TOKEN" \
            -H "Content-Type: application/json" \
            -d "{\"channel\":\"$SLACK_CHANNEL\",\"text\":\"Release \`$TAG\`\"}" \
            | jq -r '.ts')
          echo "$TS" > .slack-thread-ts

      - uses: goreleaser/goreleaser-action@v6
        with:
          args: release
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.goreleaser.yml:

archives:
  - files:
      - .slack-thread-ts

Behavior summary:

Example Notification Content

🚀 Automatic shipping started by Dewy (v1.2.3: server)

✅ Downloaded artifact for v1.2.3

🔄 Server restarted for v1.2.3

❌ Deploy failed: connection timeout

Email Notifications

Basic configuration

# Basic format
smtp://<smtp-host>:<port>/<recipient>

# Example
dewy server --registry ghr://owner/repo \
  --notifier smtp://smtp.gmail.com:587/admin@example.com \
  -- /opt/myapp/current/myapp

Environment variables

# SMTP authentication info
export MAIL_USERNAME=sender@gmail.com
export MAIL_PASSWORD=app-specific-password
export MAIL_FROM=sender@gmail.com

Configuration Options

URL Format Configuration

# Specify all settings with URL parameters
dewy server --registry ghr://owner/repo \
  --notifier "smtp://smtp.gmail.com:587/admin@example.com?username=sender@gmail.com&password=app-password&from=sender@gmail.com&subject=Deploy+Notification"

Gmail Configuration Example

# Use environment variables
export MAIL_USERNAME=sender@gmail.com
export MAIL_PASSWORD=your-app-password
export MAIL_FROM=sender@gmail.com

# Execute Dewy
dewy server --registry ghr://owner/repo \
  --notifier "smtp://smtp.gmail.com:587/admin@example.com?subject=MyApp+Deploy"

Error Notification Limits

Dewy limits consecutive error notifications to prevent spam.

• Limit start: After 3 consecutive errors, notifications are suppressed
• Limit release: Automatically released when normal operation resumes
• Behavior during limits: Logs are recorded but notifications are not sent

Multiple Environment Notification Configuration

Environment-specific Channels

# Production environment
dewy server --registry ghr://owner/repo \
  --notifier "slack://prod-deploy?title=MyApp+Production"

# Staging environment
dewy server --registry "ghr://owner/repo?pre-release=true" \
  --notifier "slack://staging-deploy?title=MyApp+Staging"

# Development environment
dewy server --registry "ghr://owner/repo?pre-release=true" \
  --notifier "slack://dev-deploy?title=MyApp+Development"

Troubleshooting

Slack notifications not arriving

1. Check token

   # Test token
   curl -H "Authorization: Bearer $SLACK_TOKEN" \
     https://slack.com/api/auth.test
   

2. Check permissions
   • Are chat:write and chat:write.customize set in Bot Token Scopes?
   • Is the App installed in the workspace?
3. Check channel name

   # For public channels, exclude #
   # ❌ slack://#deployments
   # ✅ slack://deployments
   

4. Check Bot invitation
   • Is the Bot invited to the channel? (required for both public and private channels)

Email notifications not sending

1. Check SMTP settings

   # Test SMTP server connection
   telnet smtp.gmail.com 587
   

2. Check authentication info

   # Check environment variables
   echo $MAIL_USERNAME
   echo $MAIL_FROM
   # Don't display password
   

3. Check TLS settings

   # Test with TLS disabled (not recommended)
   dewy server --registry ghr://owner/repo \
     --notifier "smtp://smtp.example.com:25/admin@example.com?tls=false"
   

The notification feature enables sharing deployment status across teams and enables early problem detection and response. Build an efficient operational system with appropriate notification settings.