expand build arguments in log #6327
Description
Issue Description
Buildah/Podman does not expand build arguments in the logs. The build logs/steps display the unexpanded contents of the Containerfile instructions, e.g., [1/2] STEP 5/9: RUN mkdir $NEWROOT.
Docker/Buildkit does the expansions (e.g., [builder 2/5] RUN mkdir /new-root-fs) which is extremely helpful to debug/analyze if the expansion during the build process works as expected.
I would love Buildah to expand the variables as well. I couldn't wrap my head around an issue where the build succeeded but didn't provide the build artifact I expected. Trying docker build helped me debug the issue and correct the Containerfile.
Steps to reproduce the issue
Steps to reproduce the issue
[root@lima-fedora tmp.cGoHObl9M4]# cat Containerfile
FROM fedora:rawhide
ARG FOO=foo
RUN echo $FOO
[root@lima-fedora tmp.cGoHObl9M4]# buildah build -f Containerfile .
STEP 1/3: FROM fedora:rawhide
STEP 2/3: ARG FOO=foo
STEP 3/3: RUN echo $FOO
[...]
[root@lima-fedora tmp.cGoHObl9M4]# docker build -f Containerfile .
[..] 0.0s
=> CACHED [1/2] FROM docker.io/library/fedora:rawhide@sha256:af660adb8de42682b494c7d102860c155466ba61cd850a8420e1ffad1764b1b7 0.0s
=> [2/2] RUN echo foo 0.1s
[...]
Describe the results you received
RUN echo $FOO
Describe the results you expected
RUN echo foo
buildah version output
Version: 1.40.1
Go Version: go1.24.3
Image Spec: 1.1.1
Runtime Spec: 1.2.1
CNI Spec: 1.1.0
libcni Version:
image Version: 5.35.0
Git Commit:
Built: Thu Jun 5 16:13:27 2025
OS/Arch: linux/arm64
BuildPlatform: linux/arm64/v8buildah info output
{
"host": {
"CgroupVersion": "v2",
"Distribution": {
"distribution": "fedora",
"version": "42"
},
"MemFree": 174956544,
"MemTotal": 4082163712,
"OCIRuntime": "crun",
"SwapFree": 4082102272,
"SwapTotal": 4082102272,
"arch": "arm64",
"cpus": 4,
"hostname": "lima-fedora",
"kernel": "6.14.0-63.fc42.aarch64",
"os": "linux",
"rootless": false,
"uptime": "6h 4m 56.52s (Approximately 0.25 days)",
"variant": ""
},
"store": {
"ContainerStore": {
"number": 0
},
"GraphDriverName": "overlay",
"GraphOptions": [
"overlay.imagestore=/usr/lib/containers/storage",
"overlay.mountopt=nodev,metacopy=on"
],
"GraphRoot": "/var/lib/containers/storage",
"GraphStatus": {
"Backing Filesystem": "btrfs",
"Native Overlay Diff": "false",
"Supports d_type": "true",
"Supports shifting": "true",
"Supports volatile": "true",
"Using metacopy": "true"
},
"ImageStore": {
"number": 2
},
"RunRoot": "/run/containers/storage"
}
}Provide your storage.conf
Standard F42Upstream Latest Release
Yes
Additional environment details
Additional environment details
Additional information
Additional information like issue happens only occasionally or issue happens with a particular architecture or on a particular setting