I run a Dockerized monolithic application in ECS, and I'll be switching to Kubernetes soon. I am 100% sold on this approach and will never go back to any deployment methods that I've used in the past (Capistrano, Ansible, Chef, Puppet, Saltstack, etc.)

I use Convox [1] which makes everything extremely simple and easy to set up on any Cloud provider. They have some paid options, but their convox/rack [2] project is completely free and open source. I manage everything from the command-line and don't use their web UI. It's just as easy as Heroku:

    convox rack install aws production

    convox apps create my_app

    convox env set FOO=bar

    convox deploy

You can also run a single command to set up a new RDS database, Redis instance, S3 bucket, etc. Convox manages absolutely everything: secure VPC, application load balancer, SSL certificates, logs sent to CloudWatch, etc. You can also set up a private rack where none of your instances have a public IP address, and all traffic is sent through a NAT gateway:

    convox rack params set Private=true

This single command sets up HIPAA and PCI compliant server infrastructure out of the box. Convox automatically creates all the required infrastructure and migrates your containers onto new EC2 instances. All with zero downtime. Now, all you need to do is sign a BAA with AWS and make sure your application and company complies with regulations (access control, encryption, audit logs, company policies, etc.)

I run a simple monolithic application where I build a single Docker image, and I run this in multiple Docker containers across 3+ EC2 instances. This has made it incredibly easy to maintain 100% uptime for over 2 years. There were a few times where I've had to fix some things in CloudFormation or roll back a failed deploy, but I've never had any downtime.

My Docker images would be much smaller and faster if I built my backend server with C++ or Rust instead of Ruby on Rails. But I would absolutely still package a C++ application in a Docker image and use ECS / Kubernetes to manage my infrastructure. I think the main benefit of Docker is that you can build and re-use consistent images across CI, development, staging, and production. So all of my Debian packages are exactly the same version, and now I spend almost zero time trying to debug strange issues that only happen on CI, etc.

So now I already know I want to use Docker because of all these benefits, and the next question is just "How can I run my Docker containers in production?". Kubernetes just happens to be the best option. The next question is "What's the easiest way to set up Docker and Kubernetes?" Convox is the holy grail.

The application language or framework isn't really relevant to the discussion.

[1] https://convox.com

[2] https://github.com/convox/rack

P.S. Things move really fast in this ecosystem, so I wouldn't be surprised if there are some other really good options. But Convox has worked really well for me over the last few years.