releasing package livecd-rootfs version 2.719.1

With that, the Dockerfile modifications[0] currently done externally
are done now here. That means that the created rootfs tarball can be
directly used within a Dockerfile to create a container from scratch:

FROM scratch
ADD livecd.ubuntu-oci.rootfs.tar.gz /
CMD ["/bin/bash"]

[0]
https://github.com/tianon/docker-brew-ubuntu-core/blob/master/update.sh

(cherry picked from commit a81972a58b004897bf3e5c14ff371bc2f6b5e4b8)

debian/changelog

@@ -1,3 +1,12 @@
+livecd-rootfs (2.719.1) hirsute; urgency=medium
+
+  [ Thomas Bechtold ]
+  * Add a new ubuntu-oci project that contains the customizations currently
+    performed downstream for the official Ubuntu images on dockerhub.
+    (LP: #1926732)
+
+ -- Michael Hudson-Doyle <michael.hudson@ubuntu.com>  Tue, 11 May 2021 11:34:58 +1200
+
 livecd-rootfs (2.719) hirsute; urgency=medium
 
   * Our raspi server images should have used the raspi-server seed in hirsute,

live-build/auto/build

@@ -245,7 +245,7 @@ if  [ "$(dpkg-divert --truename /usr/bin/man)" = "/usr/bin/man.REAL" ]; then
 fi
 EOF
 
-                if [ "$PROJECT" != "ubuntu-base" ]; then
+                if [ "$PROJECT" != "ubuntu-base" ] && [ "$PROJECT" != "ubuntu-oci" ]; then
                     	# ubuntu-minimal is too much for a docker container (it contains
                     	# systemd and other things)
 	                cat >> chroot/usr/local/sbin/unminimize <<'EOF'
@@ -441,6 +441,10 @@ serial: $BUILDSTAMP
 EOF
 		fi
 
+		if [ "$PROJECT" = "ubuntu-oci" ]; then
+		    configure_oci chroot
+		fi
+
 		configure_network_manager
 
 		echo "===== Checking size of /usr/share/doc ====="

live-build/auto/config

@@ -514,7 +514,7 @@ if [ "$PREINSTALLED" = "true" ]; then
 		ubuntu-server)
 			add_package live oem-config-debconf ubiquity-frontend-debconf
 			;;
-		ubuntu-core|ubuntu-base|base|ubuntu-cpc)
+		ubuntu-core|ubuntu-base|ubuntu-oci|base|ubuntu-cpc)
 			;;
 		ubuntu)
 			add_package live oem-config-gtk ubiquity-frontend-gtk
@@ -796,6 +796,10 @@ case $PROJECT in
 		OPTS="${OPTS:+$OPTS }--bootstrap-flavour=minimal"
 		;;
 
+	ubuntu-oci)
+		OPTS="${OPTS:+$OPTS }--bootstrap-flavour=minimal"
+		;;
+
 	ubuntu-cpc)
 		KERNEL_FLAVOURS=virtual
 
@@ -962,7 +966,7 @@ case $ARCH in
 esac
 
 case $PROJECT:${SUBPROJECT:-} in
-	ubuntu-server:*|ubuntu-base:*)
+	ubuntu-server:*|ubuntu-base:*|ubuntu-oci:*)
 		OPTS="${OPTS:+$OPTS }--linux-packages=none --initramfs=none"
 		KERNEL_FLAVOURS=none
 		BINARY_REMOVE_LINUX=false
@@ -1029,7 +1033,7 @@ echo "SUBPROJECT=\"${SUBPROJECT:-}\"" >> config/binary
 echo "LB_DISTRIBUTION=\"$SUITE\"" >> config/binary
 
 case $PROJECT in
-  ubuntu-cpc|ubuntu-core|ubuntu-base|base)
+  ubuntu-cpc|ubuntu-core|ubuntu-base|ubuntu-oci|base)
     # ubuntu-cpc gets this added in 025-create-groups.chroot, and we do
     # not want this group in projects that are effectively just chroots
     ;;

live-build/functions

@@ -833,7 +833,7 @@ clean_debian_chroot() {
     rm -f chroot/var/cache/debconf/*-old chroot/var/lib/dpkg/*-old
     Chroot chroot apt clean
     # For the docker images we remove even more stuff.
-    if [ "${PROJECT}:${SUBPROJECT:-}" = "ubuntu-base:minimized" ]; then
+    if [ "${PROJECT}:${SUBPROJECT:-}" = "ubuntu-base:minimized" ] || [ "${PROJECT}:${SUBPROJECT:-}" = "ubuntu-oci:minimized" ]; then
         # Remove apt lists (that are currently removed downstream
         # anyway)
         rm -rf chroot/var/lib/apt/lists/*
@@ -906,6 +906,62 @@ EOF
 fi
 }
 
+configure_oci() {
+    # configure a chroot to be a OCI/docker container
+    # theses changes are taken from the current Dockerfile modifications done
+    # at https://github.com/tianon/docker-brew-ubuntu-core/blob/master/update.sh
+
+    local chroot=$1
+
+    echo "==== Configuring OCI ===="
+
+    # https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L40-L48
+    echo '#!/bin/sh' > ${chroot}/usr/sbin/policy-rc.d
+    echo 'exit 101' >> ${chroot}/usr/sbin/policy-rc.d
+    Chroot ${chroot} "chmod +x /usr/sbin/policy-rc.d"
+
+    # https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L54-L56
+    Chroot ${chroot} "dpkg-divert --local --rename --add /sbin/initctl"
+    cp -a ${chroot}/usr/sbin/policy-rc.d ${chroot}/sbin/initctl
+    sed -i 's/^exit.*/exit 0/' ${chroot}/sbin/initctl
+
+    # https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L71-L78
+    echo 'force-unsafe-io' > ${chroot}/etc/dpkg/dpkg.cfg.d/docker-apt-speedup
+
+    # https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L85-L105
+    echo 'DPkg::Post-Invoke { "rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true"; };' > ${chroot}/etc/apt/apt.conf.d/docker-clean
+
+    echo 'APT::Update::Post-Invoke { "rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true"; };' >> ${chroot}/etc/apt/apt.conf.d/docker-clean
+
+    echo 'Dir::Cache::pkgcache ""; Dir::Cache::srcpkgcache "";' >> ${chroot}/etc/apt/apt.conf.d/docker-clean
+
+    # https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L109-L115
+    echo 'Acquire::Languages "none";' > ${chroot}/etc/apt/apt.conf.d/docker-no-languages
+
+    # https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L118-L130
+    echo 'Acquire::GzipIndexes "true"; Acquire::CompressionTypes::Order:: "gz";' > ${chroot}/etc/apt/apt.conf.d/docker-gzip-indexes
+
+    # https://github.com/docker/docker/blob/9a9fc01af8fb5d98b8eec0740716226fadb3735c/contrib/mkimage/debootstrap#L134-L151
+    echo 'Apt::AutoRemove::SuggestsImportant "false";' > ${chroot}/etc/apt/apt.conf.d/docker-autoremove-suggests
+
+    # delete all the apt list files since they're big and get stale quickly
+    rm -rf ${chroot}/var/lib/apt/lists/*
+
+    # verify that the APT lists files do not exist
+    Chroot chroot "apt-get indextargets" > indextargets.out
+    [ ! -s indextargets.out ]
+    rm indextargets.out
+    # (see https://bugs.launchpad.net/cloud-images/+bug/1699913)
+
+    # make systemd-detect-virt return "docker"
+    # See: https://github.com/systemd/systemd/blob/aa0c34279ee40bce2f9681b496922dedbadfca19/src/basic/virt.c#L434
+    mkdir -p ${chroot}/run/systemd
+    echo 'docker' > ${chroot}/run/systemd/container
+
+    rm -rf ${chroot}/var/cache/apt/*.bin
+    echo "==== Configuring OCI done ===="
+}
+
 configure_network_manager() {
     # If the image pre-installs network-manager, let it manage all devices by
     # default. Installing NM on an existing system only manages wifi and wwan via