e.g. with busybox image:
OCI runtime create failed: container_linux.go:348:
starting container process caused "process_linux.go:402:
container init caused \"rootfs_linux.go:58:
mounting \\\"proc\\\" to rootfs \\\"/.../rootfs\\\" at \\\"/proc\\\"
caused \\\"mkdir /.../rootfs/proc: read-only file system\\\"\"": unknown
This is because we were setting the underlying snapshot readonly so the various
mountpoints (here /proc) cannot be created. This would not be necessary if
those mountpoints were present in images but they typically are not.
The right way to get around this (used e.g. by `ctr`) is to use a writeable
snapshot but to set root readonly in the OCI spec. In this configuration the
rootfs is writeable when mounts are processed but is then made readonly by the
runtime (runc) just before entering the user specified binary within the
container.
This involved a surprising amount of plumbing.
Use this new found ability in the dockerfile converter's `dispatchCopy`
function.
Signed-off-by: Ian Campbell <ijc@docker.com>
Otherwise the daemon panics when generating the OCI spec.
For belt and braces check in the ExecOp Run function but also when generating the spec.
Signed-off-by: Ian Campbell <ijc@docker.com>
Ian Campbell
Tonis Tiigi