Dockerfile.rootfs: drop dangling /etc/resolv.conf symlink#205
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The rootfs image ships /etc/resolv.conf as a symlink to /tmp/resolv.conf. In a build context /tmp is empty, so the symlink dangles and older buildkit fails any RUN step on the image with: make mountpoint "/etc/resolv.conf": file exists when it tries to bind-mount the build-time resolv.conf over it. Docker injects its own /etc/resolv.conf at runtime regardless, so the shipped symlink serves no purpose in the container image. Remove it in the builder stage before it is copied into the final scratch image. Verified with `docker save` that no layer contains etc/resolv.conf after the change, and that DNS still resolves at runtime via Docker's mounted resolv.conf (nslookup downloads.openwrt.org succeeds). Fixes: openwrt#191 Signed-off-by: Maxim Skokov <skokov.m020709@gmail.com>
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What
/etc/resolv.confin the rootfs image is a symlink to/tmp/resolv.conf. Ina build context
/tmpis empty, so the symlink dangles and older buildkitfails any
RUNon the image with:while trying to bind-mount the build-time resolv.conf over it, which makes
FROM openwrt/rootfs+ anyRUNunusable as a base image (#191). Dockerinjects its own
/etc/resolv.confat runtime anyway, so the shipped symlinkis useless in the container image.
Removed in the builder stage before the rootfs is copied into the final
scratchimage, so real firmware (where the symlink is intentional) isuntouched.
Verification
docker saveof the rebuilt image: no layer containsetc/resolv.conf(before:
lrwxrwxrwx etc/resolv.conf -> /tmp/resolv.conf).nslookup downloads.openwrt.orgresolves viaDocker's mounted resolv.conf.
longer reproduces, so it was fixed upstream in buildkit at some point and
the reporter hit it on an older version. The dangling symlink is still
shipped though and breaks older buildkit for no benefit, so removing it is
worthwhile and side-effect-free.
Fixes #191