mirror of
https://github.com/bitnami/minideb.git
synced 2026-06-04 10:13:55 +08:00
James Westby
b4db65f619
These depend on the build environment, but differences don't show up inside the docker image as docker sets the content of these files when starting a container. We can put static values in the files to stop the image layers differing without affecting the running containers in any way. This wasn't caught by the reproducibility check as the values will be pretty static when built on the same host. (hostname will be fixed, and resolv.conf will only change if the networking configration changes enough, and that is unlikely to happen)
244 lines
10 KiB
Bash
Executable File
244 lines
10 KiB
Bash
Executable File
#!/bin/bash
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set -e
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set -u
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set -o pipefail
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ROOT=$(cd $(dirname $0) && pwd)
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TARGET=${1:?Specify the target filename}
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DIST=${2:-stable}
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LOGFILE=${TARGET}.log
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>$LOGFILE
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exec > >(tee -ia $LOGFILE)
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exec 2> >(tee -ia $LOGFILE >&2)
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DEBOOTSTRAP_DIR=$(mktemp -d)
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cp -a /usr/share/debootstrap/* $DEBOOTSTRAP_DIR
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cp -a /usr/share/keyrings/debian-archive-keyring.gpg $DEBOOTSTRAP_DIR
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cp -a $ROOT/debootstrap/* $DEBOOTSTRAP_DIR/scripts
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KEYRING=$DEBOOTSTRAP_DIR/debian-archive-keyring.gpg
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if [ -f $ROOT/keys/$DIST.gpg ]; then
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gpg --no-default-keyring --keyring $KEYRING --import $ROOT/keys/$DIST.gpg
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fi
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export DEBIAN_FRONTEND=noninteractive
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DIRS_TO_TRIM="/usr/share/man
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/var/cache/apt
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/var/lib/apt/lists
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/usr/share/locale
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/var/log
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/usr/share/info
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"
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rootfsDir=$(mktemp -d)
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echo "Building base in $rootfsDir"
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DEBOOTSTRAP_DIR=$DEBOOTSTRAP_DIR debootstrap --keyring $KEYRING --variant container --foreign ${DIST} "$rootfsDir"
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chroot "$rootfsDir" bash debootstrap/debootstrap --second-stage
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echo -e "deb http://httpredir.debian.org/debian $DIST main" > "$rootfsDir/etc/apt/sources.list"
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if [ "$DIST" != "unstable" ]; then
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echo "deb http://security.debian.org/ $DIST/updates main" >> "$rootfsDir/etc/apt/sources.list"
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fi
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chroot "$rootfsDir" apt-get update
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chroot "$rootfsDir" apt-get upgrade -y -o Dpkg::Options::="--force-confdef"
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chroot "$rootfsDir" dpkg -l | tee "$TARGET.manifest"
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echo "Applying docker-specific tweaks"
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# These are copied from the docker contrib/mkimage/debootstrap script.
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# Modifications:
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# - remove `strings` check for applying the --force-unsafe-io tweak.
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# This was sometimes wrongly detected as not applying, and we aren't
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# interested in building versions that this guard would apply to,
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# so simply apply the tweak unconditionally.
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# get path to "chroot" in our current PATH
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chrootPath="$(type -P chroot)"
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rootfs_chroot() {
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# "chroot" doesn't set PATH, so we need to set it explicitly to something our new debootstrap chroot can use appropriately!
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# set PATH and chroot away!
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PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin' \
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"$chrootPath" "$rootfsDir" "$@"
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}
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# prevent init scripts from running during install/update
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echo >&2 "+ echo exit 101 > '$rootfsDir/usr/sbin/policy-rc.d'"
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cat > "$rootfsDir/usr/sbin/policy-rc.d" <<-'EOF'
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#!/bin/sh
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# For most Docker users, "apt-get install" only happens during "docker build",
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# where starting services doesn't work and often fails in humorous ways. This
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# prevents those failures by stopping the services from attempting to start.
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exit 101
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EOF
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chmod +x "$rootfsDir/usr/sbin/policy-rc.d"
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# prevent upstart scripts from running during install/update
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(
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set -x
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rootfs_chroot dpkg-divert --local --rename --add /sbin/initctl
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cp -a "$rootfsDir/usr/sbin/policy-rc.d" "$rootfsDir/sbin/initctl"
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sed -i 's/^exit.*/exit 0/' "$rootfsDir/sbin/initctl"
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)
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# shrink a little, since apt makes us cache-fat (wheezy: ~157.5MB vs ~120MB)
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( set -x; rootfs_chroot apt-get clean )
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# this file is one APT creates to make sure we don't "autoremove" our currently
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# in-use kernel, which doesn't really apply to debootstraps/Docker images that
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# don't even have kernels installed
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rm -f "$rootfsDir/etc/apt/apt.conf.d/01autoremove-kernels"
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# force dpkg not to call sync() after package extraction (speeding up installs)
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echo >&2 "+ echo force-unsafe-io > '$rootfsDir/etc/dpkg/dpkg.cfg.d/docker-apt-speedup'"
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cat > "$rootfsDir/etc/dpkg/dpkg.cfg.d/docker-apt-speedup" <<-'EOF'
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# For most Docker users, package installs happen during "docker build", which
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# doesn't survive power loss and gets restarted clean afterwards anyhow, so
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# this minor tweak gives us a nice speedup (much nicer on spinning disks,
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# obviously).
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force-unsafe-io
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EOF
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if [ -d "$rootfsDir/etc/apt/apt.conf.d" ]; then
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# _keep_ us lean by effectively running "apt-get clean" after every install
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aptGetClean='"rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true";'
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echo >&2 "+ cat > '$rootfsDir/etc/apt/apt.conf.d/docker-clean'"
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cat > "$rootfsDir/etc/apt/apt.conf.d/docker-clean" <<-EOF
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# Since for most Docker users, package installs happen in "docker build" steps,
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# they essentially become individual layers due to the way Docker handles
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# layering, especially using CoW filesystems. What this means for us is that
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# the caches that APT keeps end up just wasting space in those layers, making
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# our layers unnecessarily large (especially since we'll normally never use
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# these caches again and will instead just "docker build" again and make a brand
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# new image).
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# Ideally, these would just be invoking "apt-get clean", but in our testing,
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# that ended up being cyclic and we got stuck on APT's lock, so we get this fun
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# creation that's essentially just "apt-get clean".
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DPkg::Post-Invoke { ${aptGetClean} };
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APT::Update::Post-Invoke { ${aptGetClean} };
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Dir::Cache::pkgcache "";
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Dir::Cache::srcpkgcache "";
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# Note that we do realize this isn't the ideal way to do this, and are always
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# open to better suggestions (https://github.com/docker/docker/issues).
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EOF
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# remove apt-cache translations for fast "apt-get update"
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echo >&2 "+ echo Acquire::Languages 'none' > '$rootfsDir/etc/apt/apt.conf.d/docker-no-languages'"
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cat > "$rootfsDir/etc/apt/apt.conf.d/docker-no-languages" <<-'EOF'
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# In Docker, we don't often need the "Translations" files, so we're just wasting
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# time and space by downloading them, and this inhibits that. For users that do
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# need them, it's a simple matter to delete this file and "apt-get update". :)
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Acquire::Languages "none";
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EOF
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echo >&2 "+ echo Acquire::GzipIndexes 'true' > '$rootfsDir/etc/apt/apt.conf.d/docker-gzip-indexes'"
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cat > "$rootfsDir/etc/apt/apt.conf.d/docker-gzip-indexes" <<-'EOF'
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# Since Docker users using "RUN apt-get update && apt-get install -y ..." in
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# their Dockerfiles don't go delete the lists files afterwards, we want them to
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# be as small as possible on-disk, so we explicitly request "gz" versions and
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# tell Apt to keep them gzipped on-disk.
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# For comparison, an "apt-get update" layer without this on a pristine
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# "debian:wheezy" base image was "29.88 MB", where with this it was only
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# "8.273 MB".
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Acquire::GzipIndexes "true";
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Acquire::CompressionTypes::Order:: "gz";
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EOF
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# update "autoremove" configuration to be aggressive about removing suggests deps that weren't manually installed
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echo >&2 "+ echo Apt::AutoRemove::SuggestsImportant 'false' > '$rootfsDir/etc/apt/apt.conf.d/docker-autoremove-suggests'"
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cat > "$rootfsDir/etc/apt/apt.conf.d/docker-autoremove-suggests" <<-'EOF'
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# Since Docker users are looking for the smallest possible final images, the
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# following emerges as a very common pattern:
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# RUN apt-get update \
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# && apt-get install -y <packages> \
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# && <do some compilation work> \
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# && apt-get purge -y --auto-remove <packages>
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# By default, APT will actually _keep_ packages installed via Recommends or
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# Depends if another package Suggests them, even and including if the package
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# that originally caused them to be installed is removed. Setting this to
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# "false" ensures that APT is appropriately aggressive about removing the
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# packages it added.
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# https://aptitude.alioth.debian.org/doc/en/ch02s05s05.html#configApt-AutoRemove-SuggestsImportant
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Apt::AutoRemove::SuggestsImportant "false";
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EOF
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fi
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cat > "$rootfsDir/usr/sbin/install_packages" <<-'EOF'
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#!/bin/sh
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set -e
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set -u
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export DEBIAN_FRONTEND=noninteractive
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n=0
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max=2
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until [ $n -gt $max ]; do
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set +e
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(
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apt-get update -qq &&
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apt-get install -y --no-install-recommends "$@"
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)
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CODE=$?
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set -e
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if [ $CODE -eq 0 ]; then
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break
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fi
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if [ $n -eq $max ]; then
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exit $CODE
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fi
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echo "apt failed, retrying"
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n=$(($n + 1))
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done
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rm -r /var/lib/apt/lists /var/cache/apt/archives
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EOF
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chmod 0755 "$rootfsDir/usr/sbin/install_packages"
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# Set the password change date to a fixed date, otherwise it defaults to the current
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# date, so we get a different image every day. SOURCE_DATE_EPOCH is designed to do this, but
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# was only implemented recently, so we can't rely on it for all versions we want to build
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# We also have to copy over the backup at /etc/shadow- so that it doesn't change
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chroot "$rootfsDir" getent passwd | cut -d: -f1 | xargs -n 1 chroot "$rootfsDir" chage -d 17885 && cp "$rootfsDir/etc/shadow" "$rootfsDir/etc/shadow-"
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# Clean /etc/hostname and /etc/resolv.conf as they are based on the current env, so make
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# the chroot different. Docker doesn't care about them, as it fills them when starting
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# a container
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echo "" > "$rootfsDir/etc/resolv.conf"
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echo "host" > "$rootfsDir/etc/hostname"
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# Capture the most recent date that a package in the image was changed.
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# We don't care about the particular date, or which package it comes from,
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# we just need a date that isn't very far in the past.
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BUILD_DATE="$(find $rootfsDir/usr/share/doc -name changelog.Debian.gz -exec dpkg-parsechangelog -SDate -l'{}' \; | xargs -l -i date --date="{}" +%s | sort -n | tail -n 1)"
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echo "Trimming down"
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for DIR in $DIRS_TO_TRIM; do
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rm -r "$rootfsDir/$DIR"/*
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done
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# Remove the aux-cache as it isn't reproducible. It doesn't seem to
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# cause any problems to remove it.
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rm "$rootfsDir/var/cache/ldconfig/aux-cache"
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find "$rootfsDir/usr/share/doc" -mindepth 1 -not -name copyright -not -type d -delete
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find "$rootfsDir/usr/share/doc" -mindepth 1 -type d -empty -delete
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# Set the mtime on all files to be no older than $BUILD_DATE.
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# This is required to have the same metadata on files so that the
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# same tarball is produced. We assume that it is not important
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# that any file have a newer mtime than this.
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find "$rootfsDir" -depth -newermt "@$BUILD_DATE" -print0 | xargs -0r touch --no-dereference --date="@$BUILD_DATE"
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echo "Total size"
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du -skh "$rootfsDir"
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echo "Package sizes"
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chroot "$rootfsDir" dpkg-query -W -f '${Package} ${Installed-Size}\n'
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echo "Largest dirs"
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du "$rootfsDir" | sort -n | tail -n 20
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echo "Built in $rootfsDir"
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tar cf "$TARGET" -C "$rootfsDir" .
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rm -r "$rootfsDir"
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rm -r "$DEBOOTSTRAP_DIR"
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echo "Image built at ${TARGET}"
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