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>
- [X] put multiples workers in a single binary ("-tags containerd standalone")
- [X] add worker selector to LLB vertex metadata
- [X] s/worker/executor/g
- [X] introduce the new "worker" concept https://github.com/moby/buildkit/pull/176#discussion_r153693928
- [X] fix up CLI
- [X] fix up tests
- allow using multiples workers (requires inter-vertex cache copier, HUGE!) --> will be separate PR
Implementation notes:
- "Workers" are renamed to "executors" now
- The new "worker" instance holds an "executor" instance and its
related stuffs such as the snapshotter
- The default worker is "runc-overlay"
Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
Kunal Kushwaha
Tonis Tiigi
Ian Campbell
Akihiro Suda