Update to CentOS 8 and support command-line arguments

.dockerignore

@@ -0,0 +1 @@
+*.swp

.gitignore

@@ -0,0 +1 @@
+*.swp

Dockerfile

@@ -1,6 +1,8 @@
-FROM centos:7.6.1810
+FROM fedora:31
 
 ENV container docker
+VOLUME ["/sys/fs/cgroup"]
+
 RUN ( \
     cd /lib/systemd/system/sysinit.target.wants/; \
     for i in *; do [ $i == systemd-tmpfiles-setup.service ] || rm -f $i; done \
@@ -13,9 +15,13 @@ RUN ( \
     rm -f /lib/systemd/system/basic.target.wants/*; \
     rm -f /lib/systemd/system/anaconda.target.wants/*; \
     touch /etc/sysconfig/network
-COPY sbin/export_environment.sh /sbin/export_environment
-COPY systemd/* /etc/systemd/system/
-RUN chmod +x /sbin/export_environment
-RUN systemctl enable export-environment.service
-VOLUME ["/sys/fs/cgroup"]
-CMD ["/usr/sbin/init"]
+
+COPY sbin/ /sbin/
+COPY etc/ /etc/
+
+ENV ARGS_EXPORT_PATH=/etc/ci-container.args
+# A list of variables to be made available in the environment the given command
+# line args run in
+ENV ARGS_ENV_INCLUDE="ARGS_EXPORT_PATH"
+
+ENTRYPOINT ["/sbin/entrypoint.sh"]

etc/systemd/journald.conf

@@ -0,0 +1,42 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+#
+# Entries in this file show the compile time defaults.
+# You can change settings by editing this file.
+# Defaults can be restored by simply deleting this file.
+#
+# See journald.conf(5) for details.
+
+[Journal]
+#Storage=auto
+#Compress=yes
+#Seal=yes
+#SplitMode=uid
+#SyncIntervalSec=5m
+#RateLimitIntervalSec=30s
+#RateLimitBurst=10000
+#SystemMaxUse=
+#SystemKeepFree=
+#SystemMaxFileSize=
+#SystemMaxFiles=100
+#RuntimeMaxUse=
+#RuntimeKeepFree=
+#RuntimeMaxFileSize=
+#RuntimeMaxFiles=100
+#MaxRetentionSec=
+#MaxFileSec=1month
+#ForwardToSyslog=no
+#ForwardToKMsg=no
+ForwardToConsole=yes
+#ForwardToWall=yes
+TTYPath=/dev/console
+#MaxLevelStore=debug
+#MaxLevelSyslog=debug
+#MaxLevelKMsg=notice
+MaxLevelConsole=debug
+#MaxLevelWall=emerg
+#LineMax=48K

etc/systemd/system/run-args.service.in

@@ -0,0 +1,14 @@
+[Unit]
+Description=Run container command
+
+[Service]
+Type=oneshot
+PassEnvironment=ARGS_EXPORT_PATH $ARGS_ENV_INCLUDE
+# Remove this service file so that if the container layer is committed, the
+# resulting image will not contain the given command information
+ExecStartPre=-/usr/bin/systemctl disable --no-reload run-args.service
+ExecStartPre=-/usr/bin/rm -f /etc/systemd/system/run-args.service
+ExecStart=/sbin/run_args.sh ${ARGS_EXPORT_PATH}
+
+[Install]
+WantedBy=multi-user.target

sbin/entrypoint.sh

@@ -0,0 +1,25 @@
+#!/bin/bash -e
+# Read command-line arguments and store them in a file to be used later
+#
+if [[ $# -gt 0 ]] && [[ $1 ]]; then
+    # Podman seems to have an issue where `podman commit` cannot create images
+    # without a CMD setting, and adding `--change='CMD []'` results in the
+    # command being an array with a single string in it. Therefor we detect that
+    # particular case above and treat it as if a command was not given
+    echo "Got $# command-line arguments, enabling run-args service"
+    printf '%s\n' "$@" > "$ARGS_EXPORT_PATH"
+    # Update list of variables that systemd will pass to invoked process on the
+    # fly. Unfortunately this dirty `sed` is the only way to do that
+    #
+    # We create the *.service file from in *.service.in file rather then making
+    # the change to the file in-place, so that the change can be undone without
+    # leaving overlayfs records behind
+    #
+    /usr/bin/sed -re "s/\\\$ARGS_ENV_INCLUDE/$ARGS_ENV_INCLUDE/" \
+        /etc/systemd/system/run-args.service.in \
+        > /etc/systemd/system/run-args.service \
+    # Enable service to run the arguments
+    systemctl enable run-args.service
+fi
+
+exec /usr/sbin/init

sbin/run_args.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+# run_args.sh - Run command from a given file
+#
+(
+    # Run in a subshell so -e only applies to the commands in parantheses
+    set -e
+    CMD_FILE="${1:?Args file not passed to run_args.sh}"
+    if ! [[ -r "$CMD_FILE" ]]; then
+        echo "run_args.sh: Args file: '$CMD_FILE' not found"
+    fi
+    mapfile -t CMD < "$CMD_FILE"
+    # remove the file since we don't need it anymore
+    rm -f "$CMD_FILE" || :
+    # Finally run the command
+    "${CMD[@]}"
+)
+# Since this script is not running with -e the command below will always run
+systemctl exit $?
+# Exit with 0 so systemd doesn't think the service had failed
+exit 0