buildah: yum fails to run in a container built/launched with rootless buildah/podman

Description The build of CentOS 7 container base image using this approach works with docker, but not with rootless buildah/podman due to a yum failure in chroot.sh. For the detailed log, refer to centos7-buildah-podman.log on issue #362 of base-images-docker repo.

Steps to reproduce the issue: On a system running CentOS 7.6.1810, and with buildah/podman and vbatts’s shadow-utils-newxidmap installed,

$git clone https://github.com/GoogleContainerTools/base-images-docker.git
$cd base-images-docker/centos
$buildah bud -f Dockerfile.build -t builder .
$podman run --privileged -v $(pwd):/workspace builder /build.sh

Describe the results you received: In running yum -y -q --releasever=7 install yum centos-release in chroot /target ./chroot.sh in build.sh,

error: Failed to initialize NSS library There was a problem importing one of the Python modules required to run yum. The error leading to this problem was:

cannot import name ts

Please install a package which provides this module, or verify that the module is installed correctly.

It’s possible that the above module doesn’t match the current version of Python, which is: 2.7.5 (default, Apr 9 2019, 14:30:50) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]

If you cannot solve this problem yourself, please go to the yum faq at: http://yum.baseurl.org/wiki/Faq

Describe the results you expected: yum install succeeds and chroot.sh proceeds to build a base container image.

Output of rpm -q buildah or apt list buildah:

buildah-1.7.1-2.git93747b1.el7.centos.x86_64
podman-0.12.1.2-2.git9551f6b.el7.centos.x86_64

Output of buildah version:

buildah version 1.7.1 (image-spec 1.0.0, runtime-spec 1.0.0)

Output of podman version if reporting a podman build issue:

podman version 0.12.1.2

Output of cat /etc/*release:

CentOS Linux release 7.6.1810 (Core)
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"

CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"

CentOS Linux release 7.6.1810 (Core)
CentOS Linux release 7.6.1810 (Core)

Output of uname -a:

Linux osbox76 3.10.0-957.el7.x86_64 #1 SMP Thu Nov 8 23:39:32 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

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

# storage.conf is the configuration file for all tools
# that share the containers/storage libraries
# 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 = [
]

# Size is used to set a maximum size of the container image.  Only supported by
# certain container storage drivers.
size = ""

# OverrideKernelCheck tells the driver to ignore kernel checks based on kernel version
override_kernel_check = "true"

# Remap-UIDs/GIDs is the mapping from UIDs/GIDs as they should appear inside of
# a container, to 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 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 the 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 container-level ID,
# until all of the entries have been used for maps.
#
# remap-user = "storage"
# remap-group = "storage"

[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 = ""

# mountopt specifies extra mount options used when mounting the thin devices.
# mountopt = ""

# use_deferred_removal Marking device for deferred removal
# use_deferred_removal = "True"

# use_deferred_deletion Marking device for deferred deletion
# 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"

About this issue

  • Original URL
  • State: closed
  • Created 5 years ago
  • Reactions: 1
  • Comments: 17 (8 by maintainers)

Most upvoted comments

an unprivileged user (rootless) has not enough privileges for using mknod, the kernel blocks that. It doesn’t matter how many capabilities are left in the user namespace, it won’t still be able to use it.

mknod doesn’t work in containers launched with buildah run even with many capabilities, including CAP_MKNOD, enabled, refer to mknod.strace.log.

buildah run --cap-add=CAP_SYS_CHROOT --cap-add=CAP_SYS_ADMIN --cap-add=CAP_SYS_PTRACE --cap-add=CAP_MKNOD --cap-add=CAP_SETGID --cap-add=CAP_SETPCAP --cap-add=CAP_SETUID $(buildah from builder) /bin/bash

  • mkdir -p /target/dev
  • mknod /target/dev/random c 1 8 mknod: ‘/target/dev/random’: Operation not permitted
  • mknod /target/dev/urandom c 1 9 mknod: ‘/target/dev/urandom’: Operation not permitted