Docker and the success of containers is mostly due to the ease of shipping code that carries its own dependencies and can be run anywhere
I don’t disagree with you, but that also shows that most modern software is poorly written. Usually a bunch of solutions that hardly work and nobody is able to reproduce their setup in a quick, sane and secure way.
There are a many container runtimes (CRI-O, podman, mirantis, containerd, etc.). Docker is just a convenient API, containers are fully implemented just with Linux native features (namespaces, seccomp, capabilities, cgroups) and images follow an open standard (OCI).
Yes, that’s exactly point point. There are many options, yet people stick with Docker and DockerHub (that is everything but open).
In systemd you need to use 30 different options to get what using containers you achieve almost instantly and with much less hussle.
Yes… maybe we just need some automation/orchestration tool for that. This is like saying that it’s way too hard to download the rootfs of some distro, unpack it and then use unshare to launch a shell on a isolated namespace… Docker as you said provides a convenient API but it doesn’t mean we can’t do the same for systemd.
but I want to simply remind you that containers are the successor of VMs (virtualize everything!), platforms that were completely proprietary and in the hands of a handful of vendor