Cannot overwrite PATH environment variable properly

[fspaniol]

Actual behavior
Whenever I try to add anything to the PATH, the previous value is gone.

Expected behavior
Mimic the normal Docker behavior

To Reproduce
Try to build this Dockerfile:

FROM opensuse/leap:15.0

RUN echo $PATH
ENV PATH="${PATH}:a"
RUN echo $PATH

When building it directly with Docker, the output is:

Sending build context to Docker daemon  2.048kB
Step 1/4 : FROM opensuse/leap:15.0
 ---> aaf6380c86fb
Step 2/4 : RUN echo $PATH
 ---> Running in 843a7bc797ae
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
Removing intermediate container 843a7bc797ae
 ---> e868ea5e93e7
Step 3/4 : ENV PATH="${PATH}:a"
 ---> Running in 5777e406e11f
Removing intermediate container 5777e406e11f
 ---> fc531f605651
Step 4/4 : RUN echo $PATH
 ---> Running in 529207d98d8d
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:a
Removing intermediate container 529207d98d8d
 ---> 6b0409e343cc
Successfully built 6b0409e343cc

Whereas when using Kaniko, the output is:

INFO[0001] Resolved base name opensuse/leap:15.0 to opensuse/leap:15.0 
INFO[0001] Resolved base name opensuse/leap:15.0 to opensuse/leap:15.0 
INFO[0001] Downloading base image opensuse/leap:15.0    
INFO[0004] Error while retrieving image from cache: getting file info: stat /cache/sha256:ad69820fac84924293242a2c5180810e99aac4361ad422172e147de3894ddd74: no such file or directory 
INFO[0004] Downloading base image opensuse/leap:15.0    
INFO[0005] Built cross stage deps: map[]                
INFO[0005] Downloading base image opensuse/leap:15.0    
INFO[0007] Error while retrieving image from cache: getting file info: stat /cache/sha256:ad69820fac84924293242a2c5180810e99aac4361ad422172e147de3894ddd74: no such file or directory 
INFO[0007] Downloading base image opensuse/leap:15.0    
INFO[0008] Unpacking rootfs as cmd RUN echo $PATH requires it. 
INFO[0027] Taking snapshot of full filesystem...        
INFO[0030] RUN echo $PATH                               
INFO[0030] cmd: /bin/sh                                 
INFO[0030] args: [-c echo $PATH]                        
/usr/local/bin:/usr/bin:/bin:.
INFO[0030] Taking snapshot of full filesystem...        
INFO[0031] No files were changed, appending empty layer to config. No layer added to image. 
INFO[0031] ENV PATH="${PATH}:a"                         
INFO[0031] RUN echo $PATH                               
INFO[0031] cmd: /bin/sh                                 
INFO[0031] args: [-c echo $PATH]                        
:a
INFO[0031] Taking snapshot of full filesystem...        
INFO[0031] No files were changed, appending empty layer to config. No layer added to image.

One interesting thing, is that the default PATH is not the PATH from the base image that I'm extending, but instead a fixed one. This has already been reported in #650. Maybe #691 has some relation to this as well?

Kaniko image used: gcr.io/kaniko-project/executor:debug-v0.10.0 (although I have tried with many different ones)

For now, the workaround I've been using is to manually set the PATH to the one contained in the base image I'm extending :)

Thanks for the help :)

[ffoebel]

I've faced the same issue and while applying your workaround is sufficient when building your specific image, it doesn't help you when trying to offer a build pipeline for arbitrary images.

[tejal29]

Thanks, relates to #649.

[tejal29]

Currently, we only resolve environments which are set or passed via build-args. We can definitely add "$PATH" as a special case.

[prary]

#762 kind of resolve the issue, here is the output

INFO[0007] Executing 0 build triggers
INFO[0007] Unpacking rootfs as cmd RUN echo $PATH requires it.
INFO[0014] Taking snapshot of full filesystem...
INFO[0017] RUN echo $PATH
INFO[0017] cmd: /bin/sh
INFO[0017] args: [-c echo $PATH]
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
INFO[0017] Taking snapshot of full filesystem...
INFO[0020] No files were changed, appending empty layer to config. No layer added to image.
INFO[0020] ENV PATH="${PATH}:a"
INFO[0020] RUN echo $PATH
INFO[0020] cmd: /bin/sh
INFO[0020] args: [-c echo $PATH]
INFO[0020] Taking snapshot of full filesystem...
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:a
INFO[0022] No files were changed, appending empty layer to config. No layer added to image.

[tejal29]

so, i added tests on @prary branch and checked it out myself.

INFO[0005] ENV PATH="${PATH}:a"                         
DEBU[0005] Replacing environment variable {PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin} with {PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:a} in config 
INFO[0005] RUN echo $PATH                               
INFO[0005] cmd: /bin/sh                                 
INFO[0005] args: [-c echo $PATH]                        
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:a
INFO[0005] No files were changed, appending empty layer to cfg. No layer added to image. 
INFO[0005] Skipping push to container registry due to --no-push flag 
tejaldesai@@kaniko (test)$