Closed
Description
Description
Docker storage native overlay diff is disabled by default
Impact
Some Docker image build failed for error layer doesn't exist.
Environment and steps to reproduce
- Set-up:
Launch an EC2 instance from Flatcar-stable-2765.2.5.
- Task:
Build a Docker image with below Dockerfile:
# echo hello > 1
# cat <<EOF > Dockerfile
FROM scratch AS base
COPY 1 /1
FROM base
# "useless" copy works ...
COPY --from=base /1 /1
# ... and the COPY statement after it fails
COPY 1 /2
EOF
# docker build -t mytest .
Sending build context to Docker daemon 3.072kB
Step 1/5 : FROM scratch AS base
--->
Step 2/5 : COPY 1 /1
---> 6fe1b1fd9cab
Step 3/5 : FROM base
---> 6fe1b1fd9cab
Step 4/5 : COPY --from=base /1 /1
---> 12bd28054ffd
Step 5/5 : COPY 1 /2
failed to export image: failed to create image: failed to get layer sha256:ec22588dcfceca289a1df0a426789512fd73560b296eb6a64b60b14b316be019: layer does not exist
Notice overlay module features redirect_dir and metacopy are enabled and docker reports native overlay diff is disabled.
# cat /sys/module/overlay/parameters/redirect_dir
Y
# cat /sys/module/overlay/parameters/metacopy
Y
# docker info
......
Server:
......
Server Version: 19.03.15
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: false
Expected behavior
Expect the Docker image be built successfully
Additional information
The same Docker image can be built without issue by turning off overlay module features redirect_dir and metacopy.
# echo N > /sys/module/overlay/parameters/redirect_dir
# echo N > /sys/module/overlay/parameters/metacopy
# systemctl restart docker
# docker build -t mytest .
Sending build context to Docker daemon 3.072kB
Step 1/5 : FROM scratch AS base
--->
Step 2/5 : COPY 1 /1
---> Using cache
---> 6fe1b1fd9cab
Step 3/5 : FROM base
---> 6fe1b1fd9cab
Step 4/5 : COPY --from=base /1 /1
---> Using cache
---> 12bd28054ffd
Step 5/5 : COPY 1 /2
---> bf943f2dd295
Successfully built bf943f2dd295
Successfully tagged mytest:latest
Notice now Docker reports that native overlay diff is enabled
# docker info
......
Server:
......
Server Version: 19.03.15
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
......
Please add any information here that does not fit the above format.
The change that enabled the two overlay features is flatcar-archive/coreos-overlay#691. Related issue #170
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Status
Implemented