docker build --squash can create incorrect shadowed layers #38072
Description
Description
I am building images with docker build --squash. One of my image inherits from another, and tries to COPY over a file that was previously copied in the parent. It appears that sometimes when I build with --squash, this file is not overwritten in the child and has the contents set by the parent. However, if I build afterwards without squash, it correctly copies the child's file.
vwoo@ubuntu:~/shared/execute/docker$ docker build --squash -t us.gcr.io/coderpad-1189/coderpad:vb vb
Sending build context to Docker daemon 3.584kB
Step 1/5 : FROM us.gcr.io/coderpad-1189/coderpad:csharp
---> 2bd6abaee988
Step 2/5 : RUN rm *.csproj
---> Using cache
---> ea17424c4927
Step 3/5 : RUN su - coderpad -c "dotnet new console --name solution --output . --language VB && dotnet add package System.Json && dotnet add package NUnitLite && dotnet run"
---> Using cache
---> 38b6ba62c6d7
Step 4/5 : RUN rm *.vb
---> Using cache
---> 5a0d310869ef
Step 5/5 : COPY --chown=coderpad:coderpad bin /usr/local/bin
---> Using cache
---> 6bbe60888a2c
Successfully built 399a017a0656
Successfully tagged us.gcr.io/coderpad-1189/coderpad:vb
vwoo@ubuntu:~/shared/execute/docker$ docker run --entrypoint /bin/bash --rm -it us.gcr.io/coderpad-1189/coderpad:vb
root@841b7f8ce1eb:~# cat `which startshell`
#!/bin/bash
echo "$1" | base64 --decode > Solution.cs
dotnet build --verbosity q --no-restore --output . && dotnet exec solution.dll
root@841b7f8ce1eb:~# exit
vwoo@ubuntu:~/shared/execute/docker$ docker build -t us.gcr.io/coderpad-1189/coderpad:vb vb
Sending build context to Docker daemon 3.584kB
Step 1/5 : FROM us.gcr.io/coderpad-1189/coderpad:csharp
---> 2bd6abaee988
Step 2/5 : RUN rm *.csproj
---> Using cache
---> ea17424c4927
Step 3/5 : RUN su - coderpad -c "dotnet new console --name solution --output . --language VB && dotnet add package System.Json && dotnet add package NUnitLite && dotnet run"
---> Using cache
---> 38b6ba62c6d7
Step 4/5 : RUN rm *.vb
---> Using cache
---> 5a0d310869ef
Step 5/5 : COPY --chown=coderpad:coderpad bin /usr/local/bin
---> Using cache
---> 6bbe60888a2c
Successfully built 6bbe60888a2c
Successfully tagged us.gcr.io/coderpad-1189/coderpad:vb
vwoo@ubuntu:~/shared/execute/docker$ docker run --entrypoint /bin/bash --rm -it us.gcr.io/coderpad-1189/coderpad:vb
root@7e1636a3b5a3:~# cat `which startshell`
#!/bin/bash
echo "$1" | base64 --decode > Solution.vb
dotnet build --verbosity q --no-restore --output . && dotnet exec solution.dll
root@7e1636a3b5a3:~#
Notice that /usr/local/bin/startshell references a file with a .cs extension in the first run, but not after running a build without squash.
Steps to reproduce the issue:
I cannot reproduce this reliably. I believe it may have something to do with layer caching.
Describe the results you received:
See above.
Describe the results you expected:
See above.
Additional information you deem important (e.g. issue happens only occasionally):
Output of docker version:
Client:
Version: 18.06.1-ce
API version: 1.38
Go version: go1.10.3
Git commit: e68fc7a
Built: Tue Aug 21 17:24:51 2018
OS/Arch: linux/amd64
Experimental: false
Server:
Engine:
Version: 18.06.1-ce
API version: 1.38 (minimum version 1.12)
Go version: go1.10.3
Git commit: e68fc7a
Built: Tue Aug 21 17:23:15 2018
OS/Arch: linux/amd64
Experimental: true
Output of docker info:
Containers: 6
Running: 1
Paused: 0
Stopped: 5
Images: 429
Server Version: 18.06.1-ce
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: none
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge host ipvlan macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 468a545b9edcd5932818eb9de8e72413e616e86e
runc version: 69663f0bd4b60df09991c08812a60108003fa340
init version: fec3683
Security Options:
apparmor
seccomp
Profile: default
Kernel Version: 4.15.0-36-generic
Operating System: Ubuntu 18.04.1 LTS
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 1.924GiB
Name: ubuntu
ID: BAB2:FH7X:Q3WS:QGFD:EXYB:PDJX:YA6P:TCLJ:427A:5M5J:NHHA:U5GC
Docker Root Dir: /data/docker
Debug Mode (client): false
Debug Mode (server): true
File Descriptors: 32
Goroutines: 52
System Time: 2018-10-24T02:21:33.142252949Z
EventsListeners: 1
Registry: https://index.docker.io/v1/
Labels:
Experimental: true
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
WARNING: No swap limit support
Additional environment details (AWS, VirtualBox, physical, etc.):
Host system is ubuntu 18.04 running inside vmware fusion, locally.