Cerberus was developed because we did not find another solution that met all our needs at the time.
Here are some other options you may want to consider:
AWS Secrets Manager came out after Cerberus and is the official solution for secrets management with in AWS and should seriously be considered over Cerberus.
Confidant is open source solution developed by Lyft that provides user-friendly storage and access to secrets in a secure way. Uses KMS, IAM authentication, and Google OAuth.
Credstash is an easy to use credential management and distribution system that uses AWS Key Management Service (KMS) and DynamoDB.
Some people simply store credentials in S3 with SSE which can be a viable option with the right policies in place.