Intercom is pretty similar. We use EC2 hosts and no containers (other than for development/test environments and some niche third-party software that is distributed as Docker containers). Autoscaling groups are our unit of scalability, pretty much one per workload, and we treat the EC2 hosts as immutable cattle. We do a scheduled AMI build every week and replace every host. We use an internally developed software tool to deploy buildpacks to hosts - buildpacks are pre-Docker technology from Heroku that solves most of the problems containers do.

I wouldn't necessarily recommend building this from scratch today, it was largely put in place around 8 years ago, and there are few compelling reasons for us to switch.