@@ -38,13 +38,13 @@ rootfs_chroot() {

 # prevent init scripts from running during install/update

 echo >&2 "+ echo exit 101 > '$rootfsDir/usr/sbin/policy-rc.d'"

 cat > "$rootfsDir/usr/sbin/policy-rc.d" <<'EOF'

-#!/bin/sh

+	#!/bin/sh

-# For most Docker users, "apt-get install" only happens during "docker build",

-# where starting services doesn't work and often fails in humorous ways. This

-# prevents those failures by stopping the services from attempting to start.

+	# For most Docker users, "apt-get install" only happens during "docker build",

+	# where starting services doesn't work and often fails in humorous ways. This

+	# prevents those failures by stopping the services from attempting to start.

-exit 101

+	exit 101

 EOF

 chmod +x "$rootfsDir/usr/sbin/policy-rc.d"

@@ -69,12 +69,12 @@ if strings "$rootfsDir/usr/bin/dpkg" | grep -q unsafe-io; then

 	# force dpkg not to call sync() after package extraction (speeding up installs)

 	echo >&2 "+ echo force-unsafe-io > '$rootfsDir/etc/dpkg/dpkg.cfg.d/docker-apt-speedup'"

 	cat > "$rootfsDir/etc/dpkg/dpkg.cfg.d/docker-apt-speedup" <<-'EOF'

-	# For most Docker users, package installs happen during "docker build", which

-	# doesn't survive power loss and gets restarted clean afterwards anyhow, so

-	# this minor tweak gives us a nice speedup (much nicer on spinning disks,

-	# obviously).

+		# For most Docker users, package installs happen during "docker build", which

+		# doesn't survive power loss and gets restarted clean afterwards anyhow, so

+		# this minor tweak gives us a nice speedup (much nicer on spinning disks,

+		# obviously).

-	force-unsafe-io

+		force-unsafe-io

 	EOF

 fi

@@ -107,26 +107,47 @@ if [ -d "$rootfsDir/etc/apt/apt.conf.d" ]; then

 	# remove apt-cache translations for fast "apt-get update"

 	echo >&2 "+ echo Acquire::Languages 'none' > '$rootfsDir/etc/apt/apt.conf.d/docker-no-languages'"

 	cat > "$rootfsDir/etc/apt/apt.conf.d/docker-no-languages" <<-'EOF'

-	# In Docker, we don't often need the "Translations" files, so we're just wasting

-	# time and space by downloading them, and this inhibits that.  For users that do

-	# need them, it's a simple matter to delete this file and "apt-get update". :)

+		# In Docker, we don't often need the "Translations" files, so we're just wasting

+		# time and space by downloading them, and this inhibits that.  For users that do

+		# need them, it's a simple matter to delete this file and "apt-get update". :)

-	Acquire::Languages "none";

+		Acquire::Languages "none";

 	EOF

 	echo >&2 "+ echo Acquire::GzipIndexes 'true' > '$rootfsDir/etc/apt/apt.conf.d/docker-gzip-indexes'"

 	cat > "$rootfsDir/etc/apt/apt.conf.d/docker-gzip-indexes" <<-'EOF'

-	# Since Docker users using "RUN apt-get update && apt-get install -y ..." in

-	# their Dockerfiles don't go delete the lists files afterwards, we want them to

-	# be as small as possible on-disk, so we explicitly request "gz" versions and

-	# tell Apt to keep them gzipped on-disk.

+		# Since Docker users using "RUN apt-get update && apt-get install -y ..." in

+		# their Dockerfiles don't go delete the lists files afterwards, we want them to

+		# be as small as possible on-disk, so we explicitly request "gz" versions and

+		# tell Apt to keep them gzipped on-disk.

-	# For comparison, an "apt-get update" layer without this on a pristine

-	# "debian:wheezy" base image was "29.88 MB", where with this it was only

-	# "8.273 MB".

+		# For comparison, an "apt-get update" layer without this on a pristine

+		# "debian:wheezy" base image was "29.88 MB", where with this it was only

+		# "8.273 MB".

-	Acquire::GzipIndexes "true";

-	Acquire::CompressionTypes::Order:: "gz";

+		Acquire::GzipIndexes "true";

+		Acquire::CompressionTypes::Order:: "gz";

+	EOF

+

+	# update "autoremove" configuration to be aggressive about removing suggests deps that weren't manually installed

+	echo >&2 "+ echo Apt::AutoRemove::SuggestsImportant 'false' > '$rootfsDir/etc/apt/apt.conf.d/docker-autoremove-suggests'"

+	cat > "$rootfsDir/etc/apt/apt.conf.d/docker-autoremove-suggests" <<-'EOF'

+		# Since Docker users are looking for the smallest possible final images, the

+		# following emerges as a very common pattern:

+

+		#   RUN apt-get update \

+		#       && apt-get install -y <packages> \

+		#       && <do some compilation work> \

+		#       && apt-get purge -y --auto-remove <packages>

+

+		# By default, APT will actually _keep_ packages installed via Recommends or

+		# Depends if another package Suggests them, even and including if the package

+		# that originally caused them to be installed is removed.  Setting this to

+		# "false" ensures that APT is appropriately aggressive about removing the

+		# packages it added.

+

+		# https://aptitude.alioth.debian.org/doc/en/ch02s05s05.html#configApt-AutoRemove-SuggestsImportant

+		Apt::AutoRemove::SuggestsImportant "false";

 	EOF

 fi