How to design blue-green multi-env CI/CD for Kubernetes monolith migration

[RonaldM]

I'm a DevOps engineer tasked with migrating our legacy monolithic application to a microservices architecture running on Kubernetes. We have a basic cluster set up, but I'm struggling with designing an efficient CI/CD pipeline that can handle blue-green deployments and automated rollbacks. Specifically, I'm unsure about best practices for managing secrets across multiple environments and setting up proper network policies for service-to-service communication. For teams that have gone through this, what tools and patterns did you settle on for ingress, service mesh, and monitoring? How did you structure your Helm charts or Kustomize overlays to maintain sanity across dev, staging, and production? Any lessons learned on avoiding common pitfalls would be invaluable.