It depends on what you're doing inside the containers themselves. If you're simply pulling from a git repo to update a code checkout, and installing one or two

It depends on what you're doing inside the containers themselves. If you're simply pulling from a git repo to update a code checkout, and installing one or two things via apt/yum, shell script/RUN isn't so bad. If you're approaching containers more like 'lightweight VMs', the string of RUN commands gets unmaintainable, fast. That can indicate some deeper problems, but in some circumstances (and especially when making updates to your container images), using configuration management for individual containers can be helpful for the same reasons even CM-ifying a small single-purpose standalone VM can.