Podman doesn't pass ARG to ENV

[tachoknight]

Description

Aloha! When trying to build an image via Podman (it was the Podman repo that sent me here), I have found that ARG values do not get passed to ENV in the Dockerfile. This does work with Docker.

I am using Podman 1.9.1 on a new installation of Fedora 32. Buildah version is 1.14.8 (both installed via dnf).

Steps to reproduce the issue:

1. Using this Dockerfile:

FROM centos:8
ARG FOO=bar
ARG WEBROOT=https://example.org/

ENV WEBROOT="$WEBROOT/$FOO"

RUN echo "${WEBROOT}/latest-build.yml"

2. Run docker build -f ./Dockerfile . -t "nothing:nothing"

Describe the results you received:

STEP 1: FROM centos:8
STEP 2: ARG FOO=bar
--> e0570e10c8c
STEP 3: ARG WEBROOT=https://example.org/
--> cf6a073b395
STEP 4: ENV WEBROOT="$WEBROOT/$FOO"
--> 5bb67731c71
STEP 5: RUN echo "${WEBROOT}/latest-build.yml"
https://example.org//latest-build.yml
STEP 6: COMMIT nothing:nothing
--> 2b4886a3eac
2b4886a3eacb548121813dba8fa1f9e2740475961940bace77a6429896977119

Note that the result of the echo is https://example.org//latest-build.yml

Describe the results you expected:

When run using Docker:

Sending build context to Docker daemon 3.072 kB
Step 1/5 : FROM centos:8
 ---> 470671670cac
Step 2/5 : ARG FOO=bar
 ---> Running in 51af1f6d924f
 ---> 8965f2299110
Removing intermediate container 51af1f6d924f
Step 3/5 : ARG WEBROOT=https://example.org
 ---> Running in aa23d8feaa69
 ---> 6214e2a80239
Removing intermediate container aa23d8feaa69
Step 4/5 : ENV WEBROOT "$WEBROOT/$FOO"
 ---> Running in 350af92a3854
 ---> 5d7126dc1520
Removing intermediate container 350af92a3854
Step 5/5 : RUN echo "${WEBROOT}/latest-build.yml"
 ---> Running in b714c4be51d1
https://example.org/bar/latest-build.yml
 ---> 4292ac41d5e9
Removing intermediate container b714c4be51d1
Successfully built 4292ac41d5e9

The result of the echo correct: https://example.org/bar/latest-build.yml

Output of buildah version:
buildah-1.14.8-1.fc32.x86_64

Output of podman version if reporting a podman build issue:
podman version 1.9.1

Output of cat /etc/*release:

Fedora release 32 (Thirty Two)
NAME=Fedora
VERSION="32 (Server Edition)"
ID=fedora
VERSION_ID=32
VERSION_CODENAME=""
PLATFORM_ID="platform:f32"
PRETTY_NAME="Fedora 32 (Server Edition)"
ANSI_COLOR="0;34"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:32"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f32/system-administrators-guide/"
SUPPORT_URL="https://fedoraproject.org/wiki/Communicating_and_getting_help"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=32
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=32
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Server Edition"
VARIANT_ID=server
Fedora release 32 (Thirty Two)
Fedora release 32 (Thirty Two)

Output of uname -a:

Linux tkdockery 5.6.8-300.fc32.x86_64 #1 SMP Wed Apr 29 19:01:34 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Output of cat /etc/containers/storage.conf:

# This file is is the configuration file for all tools
# that use the containers/storage library.
# See man 5 containers-storage.conf for more information
# The "container storage" table contains all of the server options.
[storage]

# Default Storage Driver
driver = "overlay"

# Temporary storage location
runroot = "/var/run/containers/storage"

# Primary Read/Write location of container storage
graphroot = "/var/lib/containers/storage"

[storage.options]
# Storage options to be passed to underlying storage drivers

# AdditionalImageStores is used to pass paths to additional Read/Only image stores
# Must be comma separated list.
additionalimagestores = [
]

# Remap-UIDs/GIDs is the mapping from UIDs/GIDs as they should appear inside of
# a container, to the UIDs/GIDs as they should appear outside of the container,
# and the length of the range of UIDs/GIDs.  Additional mapped sets can be
# listed and will be heeded by libraries, but there are limits to the number of
# mappings which the kernel will allow when you later attempt to run a
# container.
#
# remap-uids = 0:1668442479:65536
# remap-gids = 0:1668442479:65536

# Remap-User/Group is a user name which can be used to look up one or more UID/GID
# ranges in the /etc/subuid or /etc/subgid file.  Mappings are set up starting
# with an in-container ID of 0 and then a host-level ID taken from the lowest
# range that matches the specified name, and using the length of that range.
# Additional ranges are then assigned, using the ranges which specify the
# lowest host-level IDs first, to the lowest not-yet-mapped in-container ID,
# until all of the entries have been used for maps.
#
# remap-user = "storage"
# remap-group = "storage"

[storage.options.overlay]
# ignore_chown_errors can be set to allow a non privileged user running with
# a single UID within a user namespace to run containers. The user can pull
# and use any image even those with multiple uids.  Note multiple UIDs will be
# squashed down to the default uid in the container.  These images will have no
# separation between the users in the container. Only supported for the overlay
# and vfs drivers.
#ignore_chown_errors = false

# Path to an helper program to use for mounting the file system instead of mounting it
# directly.
#mount_program = "/usr/bin/fuse-overlayfs"

# mountopt specifies comma separated list of extra mount options
mountopt = "nodev,metacopy=on"

# Size is used to set a maximum size of the container image.
# size = ""

[storage.options.thinpool]
# Storage Options for thinpool

# autoextend_percent determines the amount by which pool needs to be
# grown. This is specified in terms of % of pool size. So a value of 20 means
# that when threshold is hit, pool will be grown by 20% of existing
# pool size.
# autoextend_percent = "20"

# autoextend_threshold determines the pool extension threshold in terms
# of percentage of pool size. For example, if threshold is 60, that means when
# pool is 60% full, threshold has been hit.
# autoextend_threshold = "80"

# basesize specifies the size to use when creating the base device, which
# limits the size of images and containers.
# basesize = "10G"

# blocksize specifies a custom blocksize to use for the thin pool.
# blocksize="64k"

# directlvm_device specifies a custom block storage device to use for the
# thin pool. Required if you setup devicemapper.
# directlvm_device = ""

# directlvm_device_force wipes device even if device already has a filesystem.
# directlvm_device_force = "True"

# fs specifies the filesystem type to use for the base device.
# fs="xfs"

# log_level sets the log level of devicemapper.
# 0: LogLevelSuppress 0 (Default)
# 2: LogLevelFatal
# 3: LogLevelErr
# 4: LogLevelWarn
# 5: LogLevelNotice
# 6: LogLevelInfo
# 7: LogLevelDebug
# log_level = "7"

# min_free_space specifies the min free space percent in a thin pool require for
# new device creation to succeed. Valid values are from 0% - 99%.
# Value 0% disables
# min_free_space = "10%"

# mkfsarg specifies extra mkfs arguments to be used when creating the base.
# device.
# mkfsarg = ""
# Size is used to set a maximum size of the container image.
# size = ""

# use_deferred_removal marks devicemapper block device for deferred removal.
# If the thinpool is in use when the driver attempts to remove it, the driver
# tells the kernel to remove it as soon as possible. Note this does not free
# up the disk space, use deferred deletion to fully remove the thinpool.
# use_deferred_removal = "True"

# use_deferred_deletion marks thinpool device for deferred deletion.
# If the device is busy when the driver attempts to delete it, the driver
# will attempt to delete device every 30 seconds until successful.
# If the program using the driver exits, the driver will continue attempting
# to cleanup the next time the driver is used. Deferred deletion permanently
# deletes the device and all data stored in device will be lost.
# use_deferred_deletion = "True"

# xfs_nospace_max_retries specifies the maximum number of retries XFS should
# attempt to complete IO when ENOSPC (no space) error is returned by
# underlying storage device.
# xfs_nospace_max_retries = "0"

[tachoknight]

Adding an additional line:

ARG WEBROOT="$WEBROOT/$FOO"

makes it work, but this is not my Dockerfile so changing it isn't really an option.

[TomSweeneyRedHat]

@tachoknight thanks for the report. I think this may be related to #2323.

[TomSweeneyRedHat]

Scratch #2323, likely related to #2192

[TomSweeneyRedHat]

@tachoknight unfortunately the other PR did not fix this issue. While testing with this further today, I found what's happening. The issue is you have an ARG named WEBROOT and the ENV variable named WEBROOT. That should be handled appropriately, but it is not at the moment. As a test, could you rename your ARG to WEBROOT1 and see if that works for you?

[tachoknight]

@TomSweeneyRedHat That does seem to work:

STEP 1: FROM centos:8
STEP 2: ARG FOO=bar
--> de575c3c4d1
STEP 3: ARG WEBROOT1=https://example.org/
--> 6c5acd1dd30
STEP 4: ARG WEBROOT1="$WEBROOT1/$FOO"
--> 394293fe2d0
STEP 5: ENV WEBROOT="$WEBROOT1"
--> 6f7a6363492
STEP 6: RUN echo "${WEBROOT}/latest-build.yml"
https://example.org//bar/latest-build.yml
STEP 7: COMMIT nothing:nothing
--> ea80b81fd49

where I modified the Dockerfile to look like:

FROM centos:8
ARG FOO=bar
ARG WEBROOT1=https://example.org/
ARG WEBROOT1="$WEBROOT1/$FOO"

ENV WEBROOT="$WEBROOT1"

RUN echo "${WEBROOT}/latest-build.yml"

[TomSweeneyRedHat]

@tachoknight TYVM for the test and results. I'm glad that works for you too. I ran into unrelated issues last night on my test machine, hope to dig further through the ENV/ARG handling code there later today. I've a suspicion of where the issue is, but haven't been able to test it out yet.

[rhatdan]

It looks like this is fixed in upstream. Reopen if I am mistaken.