Update your bot with zero downtime

Why zero downtime?

Every time you restart your bot, users see it disconnect briefly. With the right techniques you can minimize or eliminate that dead time.

Method 1: PM2 Reload (graceful)

PM2 reload starts a new instance before killing the old one:

#!/bin/bash
# deploy.sh
cd /opt/bots/my-bot
git pull origin main
npm install --production
pm2 reload my-bot
echo "Deploy complete: $(date)"

For this to work correctly, handle graceful shutdown:

process.on('SIGINT', async () => {
  console.log('Closing connections...');
  await client.destroy();
  process.exit(0);
});

Method 2: Blue-Green with systemd

Keep two instances and alternate between them:

# Structure
/opt/bots/my-bot-blue/   # Active version
/opt/bots/my-bot-green/  # New version

Deploy script:

#!/bin/bash
ACTIVE=$(systemctl is-active discord-bot-blue && echo 'blue' || echo 'green')
NEW=$([ "$ACTIVE" = 'blue' ] && echo 'green' || echo 'blue')

cd /opt/bots/my-bot-$NEW
git pull origin main
npm install --production

# Start the new version
sudo systemctl start discord-bot-$NEW
sleep 5

# Verify it started correctly
if systemctl is-active --quiet discord-bot-$NEW; then
  sudo systemctl stop discord-bot-$ACTIVE
  echo "Switched to $NEW"
else
  sudo systemctl stop discord-bot-$NEW
  echo "Deploy failed, $ACTIVE still active"
  exit 1
fi

Method 3: CI/CD with GitHub Actions

Automate deployment on every push to main:

# .github/workflows/deploy.yml
name: Deploy Bot
on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Deploy via SSH
        uses: appleboy/ssh-action@v1
        with:
          host: ${{ secrets.VPS_HOST }}
          username: deploy
          key: ${{ secrets.SSH_PRIVATE_KEY }}
          script: |
            cd /opt/bots/my-bot
            git pull origin main
            npm install --production
            pm2 reload my-bot

Configure secrets in your GitHub repository:

• VPS_HOST: Your Baires Host VPS IP
• SSH_PRIVATE_KEY: SSH private key for the deploy user

Graceful shutdown in discord.js

const shutdown = async () => {
  console.log('Shutdown initiated...');
  // Save pending state to DB
  await saveState();
  // Disconnect the bot
  client.destroy();
  process.exit(0);
};

process.on('SIGTERM', shutdown);
process.on('SIGINT', shutdown);

Recommendations

• Use pm2 reload instead of pm2 restart for zero downtime
• Implement graceful shutdown to avoid data loss
• Test deployments in a staging environment before production
• Set up deploy success/failure notifications in Discord