Early in the history of docker, a lot of bits and bobs hadn't been worked out yet, and I had a bug land on my desk where a service was leaking memory until it crashed, but only when running in a container. Turns out, the jvm at the time just never collected in a container because the /proc directory was mounted from the host rather than the k8s scheduler. So it would only collect if it did not receive a second allocation request during the GC.

This is no longer true with buildkit - you can use the --secret to securely pass a secret in as an argument.