Twilio Profile Management & CORS Troubleshooting

This guide covers best practices for managing Twilio CLI profiles and troubleshooting common CORS issues that can occur when working with multiple environments.

Overview

The Twilio Flex template supports multiple environments (dev, staging, production) and relies on proper Twilio CLI profile configuration to ensure deployments target the correct Twilio account and Flex instance.

Common Issues

Profile/Environment Mismatch

Problem: Configuration deployed to wrong environment, CORS errors, or "403 Forbidden" errors when accessing admin UI.

Symptoms:

Admin UI fails to load with CORS errors
Serverless functions deployed to wrong account
Flex configuration pointing to wrong serverless domain

Root Cause: Twilio CLI profile doesn't match the intended deployment environment.

Profile Management Best Practices

1. Check Current Profile Status

Always verify your current Twilio CLI profile before deploying:

# Check current profile
twilio profiles:list

# Check current profile account
node scripts/print-profile-account.mjs

# Quick profile vs environment check
export profile=`node scripts/print-profile-account.mjs`; echo "Current profile account: ${profile}"

2. Verify Profile Matches Environment Files

Before deploying any component, ensure your CLI profile matches the target environment:

For Serverless Functions:

cd serverless-functions
export env=`cat .env | grep ACCOUNT_SID | cut -d '=' -f 2`
export profile=`node ../scripts/print-profile-account.mjs`
echo -e 'serverless .env: \t' ${env}
echo -e 'CLI profile: \t' ${profile}

For Flex Config:

cd flex-config
export env=`cat .env | grep ACCOUNT_SID | cut -d '=' -f 2`
export profile=`node ../scripts/print-profile-account.mjs`
echo -e 'flex-config .env: \t' ${env}
echo -e 'CLI profile: \t' ${profile}

For Add-ons:

export env=`cat addons/serverless-schedule-manager/.env | grep ACCOUNT_SID | cut -d '=' -f 2`
export profile=`node scripts/print-profile-account.mjs`
echo -e 'schedule-manager .env: \t' ${env}
echo -e 'CLI profile: \t' ${profile}

3. Switching Profiles

If your profile doesn't match the target environment:

# List available profiles
twilio profiles:list

# Switch to the correct profile
twilio profiles:use my-dev-profile

# Verify the switch
twilio profiles:list

4. Regenerating Environment Files

If you've switched profiles and need to update .env files:

# From the template root directory
npm run postinstall -- --overwrite

This will regenerate all .env files based on your current CLI profile.

CORS Troubleshooting

Understanding CORS in the Flex Template

The Twilio Flex template has built-in CORS handling via middleware. Do not add additional CORS headers unless absolutely necessary.

Common CORS Errors

Error: Access-Control-Allow-Origin header contains multiple values '*,*'

Cause: Duplicate CORS headers being added by both template middleware and custom code.

Solution: Remove custom CORS header additions and rely on template's built-in handling.

Error: No 'Access-Control-Allow-Origin' header is present

Cause: Error responses bypassing template middleware.

Solution: Add CORS headers only to error response paths.

CORS Best Practices

Use Template's Built-in CORS: The template automatically handles CORS for successful responses.
Only Add CORS to Error Paths: Add CORS headers manually only when returning error responses:

// ❌ Don't do this - duplicates template CORS
const response = new Twilio.Response();
response.appendHeader('Access-Control-Allow-Origin', '*');
response.appendHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
response.appendHeader('Access-Control-Allow-Headers', 'Content-Type');

// ✅ Do this - only for error responses
if (error) {
  const response = new Twilio.Response();
  response.appendHeader('Access-Control-Allow-Origin', '*');
  response.appendHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
  response.appendHeader('Access-Control-Allow-Headers', 'Content-Type');
  response.setStatusCode(500);
  response.setBody({ error: 'Something went wrong' });
  return callback(null, response);
}

Test CORS with Browser, Not Curl: CORS is a browser security feature. Always test with actual browser requests.
Check for OPTIONS Handling: Ensure your functions handle OPTIONS preflight requests:

exports.handler = function(context, event, callback) {
  // Handle OPTIONS preflight
  if (event.RequestMethod === 'OPTIONS') {
    const response = new Twilio.Response();
    response.appendHeader('Access-Control-Allow-Origin', '*');
    response.appendHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
    response.appendHeader('Access-Control-Allow-Headers', 'Content-Type');
    response.setStatusCode(200);
    return callback(null, response);
  }
  
  // Your function logic here...
};

Environment-Specific Configuration

Development Environment

For development, ensure your Flex configuration points to the correct serverless domain:

// flex-config/ui_attributes.production.json
{
  "custom_data": {
    "serverless_functions_domain": "custom-flex-extensions-serverless-1866-dev.twil.io"
  }
}

Verifying Serverless Domains

Check which serverless services and environments are active:

# List all serverless services
twilio api:serverless:v1:services:list

# List environments for a specific service
twilio api:serverless:v1:services:environments:list --service-sid=ZSxxxxx

Deployment Checklist

Before deploying any component:

✅ Verify CLI profile matches target environment
✅ Check .env files are up to date
✅ Ensure serverless domain in Flex config is correct
✅ Test CORS with browser requests after deployment
✅ Verify admin UI functionality

Troubleshooting Steps

If you encounter CORS or profile issues:

Check Profile Status:

twilio profiles:list
node scripts/print-profile-account.mjs

Verify Environment Alignment:

# Check all environments match
cd serverless-functions && export env=`cat .env | grep ACCOUNT_SID | cut -d '=' -f 2` && echo "Serverless: ${env}"
cd ../flex-config && export env=`cat .env | grep ACCOUNT_SID | cut -d '=' -f 2` && echo "Flex Config: ${env}"
cd .. && export profile=`node scripts/print-profile-account.mjs` && echo "CLI Profile: ${profile}"

Test CORS Headers:

# Test with curl
curl -i -X OPTIONS https://your-serverless-domain.twil.io/features/admin-ui/flex/fetch-config

# Look for single CORS headers (not duplicates)

Check Serverless Deployment Status:
```
twilio api:serverless:v1:services:list
```

Redeploy if Necessary:

# Redeploy serverless functions
cd serverless-functions && npm run deploy

# Redeploy flex config
cd ../flex-config && npm run deploy

Prevention

Always check profile before deploying
Use the verification commands provided in deployment docs
Test admin UI functionality after any configuration changes
Document any custom CORS modifications with clear comments
Keep environment files in sync with CLI profile

Overview​

Common Issues​

Profile/Environment Mismatch​

Profile Management Best Practices​

1. Check Current Profile Status​

2. Verify Profile Matches Environment Files​

3. Switching Profiles​

4. Regenerating Environment Files​

CORS Troubleshooting​

Understanding CORS in the Flex Template​

Common CORS Errors​

CORS Best Practices​

Environment-Specific Configuration​

Development Environment​

Verifying Serverless Domains​

Deployment Checklist​

Troubleshooting Steps​

Prevention​

Related Documentation​