Wrap installer in a function

This will assure that the install script will not
begin executing until after it has been downloaded should
it be utilized in a 'curl | bash' workflow.

Signed-off-by: Eric Windisch <eric@windisch.us>

hack/install.sh

@@ -20,213 +20,216 @@ command_exists() {
 	command -v "$@" > /dev/null 2>&1
 }
 
-case "$(uname -m)" in
-	*64)
-		;;
-	*)
-		echo >&2 'Error: you are not using a 64bit platform.'
-		echo >&2 'Docker currently only supports 64bit platforms.'
-		exit 1
-		;;
-esac
-
-if command_exists docker || command_exists lxc-docker; then
-	echo >&2 'Warning: "docker" or "lxc-docker" command appears to already exist.'
-	echo >&2 'Please ensure that you do not already have docker installed.'
-	echo >&2 'You may press Ctrl+C now to abort this process and rectify this situation.'
-	( set -x; sleep 20 )
-fi
-
-user="$(id -un 2>/dev/null || true)"
-
-sh_c='sh -c'
-if [ "$user" != 'root' ]; then
-	if command_exists sudo; then
-		sh_c='sudo -E sh -c'
-	elif command_exists su; then
-		sh_c='su -c'
-	else
-		echo >&2 'Error: this installer needs the ability to run commands as root.'
-		echo >&2 'We are unable to find either "sudo" or "su" available to make this happen.'
-		exit 1
+do_docker_install() {
+	case "$(uname -m)" in
+		*64)
+			;;
+		*)
+			echo >&2 'Error: you are not using a 64bit platform.'
+			echo >&2 'Docker currently only supports 64bit platforms.'
+			exit 1
+			;;
+	esac
+
+	if command_exists docker || command_exists lxc-docker; then
+		echo >&2 'Warning: "docker" or "lxc-docker" command appears to already exist.'
+		echo >&2 'Please ensure that you do not already have docker installed.'
+		echo >&2 'You may press Ctrl+C now to abort this process and rectify this situation.'
+		( set -x; sleep 20 )
 	fi
-fi
-
-curl=''
-if command_exists curl; then
-	curl='curl -sSL'
-elif command_exists wget; then
-	curl='wget -qO-'
-elif command_exists busybox && busybox --list-modules | grep -q wget; then
-	curl='busybox wget -qO-'
-fi
-
-# perform some very rudimentary platform detection
-lsb_dist=''
-if command_exists lsb_release; then
-	lsb_dist="$(lsb_release -si)"
-fi
-if [ -z "$lsb_dist" ] && [ -r /etc/lsb-release ]; then
-	lsb_dist="$(. /etc/lsb-release && echo "$DISTRIB_ID")"
-fi
-if [ -z "$lsb_dist" ] && [ -r /etc/debian_version ]; then
-	lsb_dist='debian'
-fi
-if [ -z "$lsb_dist" ] && [ -r /etc/fedora-release ]; then
-	lsb_dist='fedora'
-fi
-if [ -z "$lsb_dist" ] && [ -r /etc/os-release ]; then
-	lsb_dist="$(. /etc/os-release && echo "$ID")"
-fi
-
-lsb_dist="$(echo "$lsb_dist" | tr '[:upper:]' '[:lower:]')"
-case "$lsb_dist" in
-	amzn|fedora|centos)
-		if [ "$lsb_dist" = 'amzn' ]; then
-			(
-				set -x
-				$sh_c 'sleep 3; yum -y -q install docker'
-			)
+
+	user="$(id -un 2>/dev/null || true)"
+
+	sh_c='sh -c'
+	if [ "$user" != 'root' ]; then
+		if command_exists sudo; then
+			sh_c='sudo -E sh -c'
+		elif command_exists su; then
+			sh_c='su -c'
 		else
-			(
-				set -x
-				$sh_c 'sleep 3; yum -y -q install docker-io'
-			)
-		fi
-		if command_exists docker && [ -e /var/run/docker.sock ]; then
-			(
-				set -x
-				$sh_c 'docker version'
-			) || true
+			echo >&2 'Error: this installer needs the ability to run commands as root.'
+			echo >&2 'We are unable to find either "sudo" or "su" available to make this happen.'
+			exit 1
 		fi
-		your_user=your-user
-		[ "$user" != 'root' ] && your_user="$user"
-		echo
-		echo 'If you would like to use Docker as a non-root user, you should now consider'
-		echo 'adding your user to the "docker" group with something like:'
-		echo
-		echo '  sudo usermod -aG docker' $your_user
-		echo
-		echo 'Remember that you will have to log out and back in for this to take effect!'
-		echo
-		exit 0
-		;;
-
-	ubuntu|debian|linuxmint)
-		export DEBIAN_FRONTEND=noninteractive
-
-		did_apt_get_update=
-		apt_get_update() {
-			if [ -z "$did_apt_get_update" ]; then
-				( set -x; $sh_c 'sleep 3; apt-get update' )
-				did_apt_get_update=1
-			fi
-		}
+	fi
 
-		# aufs is preferred over devicemapper; try to ensure the driver is available.
-		if ! grep -q aufs /proc/filesystems && ! $sh_c 'modprobe aufs'; then
-			if uname -r | grep -q -- '-generic' && dpkg -l 'linux-image-*-generic' | grep -q '^ii' 2>/dev/null; then
-				kern_extras="linux-image-extra-$(uname -r) linux-image-extra-virtual"
+	curl=''
+	if command_exists curl; then
+		curl='curl -sSL'
+	elif command_exists wget; then
+		curl='wget -qO-'
+	elif command_exists busybox && busybox --list-modules | grep -q wget; then
+		curl='busybox wget -qO-'
+	fi
 
-				apt_get_update
-				( set -x; $sh_c 'sleep 3; apt-get install -y -q '"$kern_extras" ) || true
+	# perform some very rudimentary platform detection
+	lsb_dist=''
+	if command_exists lsb_release; then
+		lsb_dist="$(lsb_release -si)"
+	fi
+	if [ -z "$lsb_dist" ] && [ -r /etc/lsb-release ]; then
+		lsb_dist="$(. /etc/lsb-release && echo "$DISTRIB_ID")"
+	fi
+	if [ -z "$lsb_dist" ] && [ -r /etc/debian_version ]; then
+		lsb_dist='debian'
+	fi
+	if [ -z "$lsb_dist" ] && [ -r /etc/fedora-release ]; then
+		lsb_dist='fedora'
+	fi
+	if [ -z "$lsb_dist" ] && [ -r /etc/os-release ]; then
+		lsb_dist="$(. /etc/os-release && echo "$ID")"
+	fi
 
-				if ! grep -q aufs /proc/filesystems && ! $sh_c 'modprobe aufs'; then
-					echo >&2 'Warning: tried to install '"$kern_extras"' (for AUFS)'
-					echo >&2 ' but we still have no AUFS.  Docker may not work. Proceeding anyways!'
+	lsb_dist="$(echo "$lsb_dist" | tr '[:upper:]' '[:lower:]')"
+	case "$lsb_dist" in
+		amzn|fedora|centos)
+			if [ "$lsb_dist" = 'amzn' ]; then
+				(
+					set -x
+					$sh_c 'sleep 3; yum -y -q install docker'
+				)
+			else
+				(
+					set -x
+					$sh_c 'sleep 3; yum -y -q install docker-io'
+				)
+			fi
+			if command_exists docker && [ -e /var/run/docker.sock ]; then
+				(
+					set -x
+					$sh_c 'docker version'
+				) || true
+			fi
+			your_user=your-user
+			[ "$user" != 'root' ] && your_user="$user"
+			echo
+			echo 'If you would like to use Docker as a non-root user, you should now consider'
+			echo 'adding your user to the "docker" group with something like:'
+			echo
+			echo '  sudo usermod -aG docker' $your_user
+			echo
+			echo 'Remember that you will have to log out and back in for this to take effect!'
+			echo
+			exit 0
+			;;
+
+		ubuntu|debian|linuxmint)
+			export DEBIAN_FRONTEND=noninteractive
+
+			did_apt_get_update=
+			apt_get_update() {
+				if [ -z "$did_apt_get_update" ]; then
+					( set -x; $sh_c 'sleep 3; apt-get update' )
+					did_apt_get_update=1
+				fi
+			}
+
+			# aufs is preferred over devicemapper; try to ensure the driver is available.
+			if ! grep -q aufs /proc/filesystems && ! $sh_c 'modprobe aufs'; then
+				if uname -r | grep -q -- '-generic' && dpkg -l 'linux-image-*-generic' | grep -q '^ii' 2>/dev/null; then
+					kern_extras="linux-image-extra-$(uname -r) linux-image-extra-virtual"
+
+					apt_get_update
+					( set -x; $sh_c 'sleep 3; apt-get install -y -q '"$kern_extras" ) || true
+
+					if ! grep -q aufs /proc/filesystems && ! $sh_c 'modprobe aufs'; then
+						echo >&2 'Warning: tried to install '"$kern_extras"' (for AUFS)'
+						echo >&2 ' but we still have no AUFS.  Docker may not work. Proceeding anyways!'
+						( set -x; sleep 10 )
+					fi
+				else
+					echo >&2 'Warning: current kernel is not supported by the linux-image-extra-virtual'
+					echo >&2 ' package.  We have no AUFS support.  Consider installing the packages'
+					echo >&2 ' linux-image-virtual kernel and linux-image-extra-virtual for AUFS support.'
 					( set -x; sleep 10 )
 				fi
-			else
-				echo >&2 'Warning: current kernel is not supported by the linux-image-extra-virtual'
-				echo >&2 ' package.  We have no AUFS support.  Consider installing the packages'
-				echo >&2 ' linux-image-virtual kernel and linux-image-extra-virtual for AUFS support.'
-				( set -x; sleep 10 )
 			fi
-		fi
 
-		# install apparmor utils if they're missing and apparmor is enabled in the kernel
-		# otherwise Docker will fail to start
-		if [ "$(cat /sys/module/apparmor/parameters/enabled 2>/dev/null)" = 'Y' ]; then
-			if command -v apparmor_parser &> /dev/null; then
-				echo 'apparmor is enabled in the kernel and apparmor utils were already installed'
-			else
-				echo 'apparmor is enabled in the kernel, but apparmor_parser missing'
-				apt_get_update
-				( set -x; $sh_c 'sleep 3; apt-get install -y -q apparmor' )
+			# install apparmor utils if they're missing and apparmor is enabled in the kernel
+			# otherwise Docker will fail to start
+			if [ "$(cat /sys/module/apparmor/parameters/enabled 2>/dev/null)" = 'Y' ]; then
+				if command -v apparmor_parser &> /dev/null; then
+					echo 'apparmor is enabled in the kernel and apparmor utils were already installed'
+				else
+					echo 'apparmor is enabled in the kernel, but apparmor_parser missing'
+					apt_get_update
+					( set -x; $sh_c 'sleep 3; apt-get install -y -q apparmor' )
+				fi
 			fi
-		fi
 
-		if [ ! -e /usr/lib/apt/methods/https ]; then
-			apt_get_update
-			( set -x; $sh_c 'sleep 3; apt-get install -y -q apt-transport-https ca-certificates' )
-		fi
-		if [ -z "$curl" ]; then
-			apt_get_update
-			( set -x; $sh_c 'sleep 3; apt-get install -y -q curl ca-certificates' )
-			curl='curl -sSL'
-		fi
-		(
-			set -x
-			if [ "https://get.docker.com/" = "$url" ]; then
-				$sh_c "apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9"
-			elif [ "https://test.docker.com/" = "$url" ]; then
-				$sh_c "apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 740B314AE3941731B942C66ADF4FD13717AAD7D6"
-			else
-				$sh_c "$curl ${url}gpg | apt-key add -"
+			if [ ! -e /usr/lib/apt/methods/https ]; then
+				apt_get_update
+				( set -x; $sh_c 'sleep 3; apt-get install -y -q apt-transport-https ca-certificates' )
+			fi
+			if [ -z "$curl" ]; then
+				apt_get_update
+				( set -x; $sh_c 'sleep 3; apt-get install -y -q curl ca-certificates' )
+				curl='curl -sSL'
 			fi
-			$sh_c "echo deb ${url}ubuntu docker main > /etc/apt/sources.list.d/docker.list"
-			$sh_c 'sleep 3; apt-get update; apt-get install -y -q lxc-docker'
-		)
-		if command_exists docker && [ -e /var/run/docker.sock ]; then
 			(
 				set -x
-				$sh_c 'docker version'
-			) || true
-		fi
-		your_user=your-user
-		[ "$user" != 'root' ] && your_user="$user"
-		echo
-		echo 'If you would like to use Docker as a non-root user, you should now consider'
-		echo 'adding your user to the "docker" group with something like:'
-		echo
-		echo '  sudo usermod -aG docker' $your_user
-		echo
-		echo 'Remember that you will have to log out and back in for this to take effect!'
-		echo
-		exit 0
-		;;
-
-	gentoo)
-		if [ "$url" = "https://test.docker.com/" ]; then
-			echo >&2
-			echo >&2 '  You appear to be trying to install the latest nightly build in Gentoo.'
-			echo >&2 '  The portage tree should contain the latest stable release of Docker, but'
-			echo >&2 '  if you want something more recent, you can always use the live ebuild'
-			echo >&2 '  provided in the "docker" overlay available via layman.  For more'
-			echo >&2 '  instructions, please see the following URL:'
-			echo >&2 '    https://github.com/tianon/docker-overlay#using-this-overlay'
-			echo >&2 '  After adding the "docker" overlay, you should be able to:'
-			echo >&2 '    emerge -av =app-emulation/docker-9999'
-			echo >&2
-			exit 1
-		fi
-
-		(
-			set -x
-			$sh_c 'sleep 3; emerge app-emulation/docker'
-		)
-		exit 0
-		;;
-esac
-
-cat >&2 <<'EOF'
-
-  Either your platform is not easily detectable, is not supported by this
-  installer script (yet - PRs welcome! [hack/install.sh]), or does not yet have
-  a package for Docker.  Please visit the following URL for more detailed
-  installation instructions:
+				if [ "https://get.docker.com/" = "$url" ]; then
+					$sh_c "apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9"
+				elif [ "https://test.docker.com/" = "$url" ]; then
+					$sh_c "apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 740B314AE3941731B942C66ADF4FD13717AAD7D6"
+				else
+					$sh_c "$curl ${url}gpg | apt-key add -"
+				fi
+				$sh_c "echo deb ${url}ubuntu docker main > /etc/apt/sources.list.d/docker.list"
+				$sh_c 'sleep 3; apt-get update; apt-get install -y -q lxc-docker'
+			)
+			if command_exists docker && [ -e /var/run/docker.sock ]; then
+				(
+					set -x
+					$sh_c 'docker version'
+				) || true
+			fi
+			your_user=your-user
+			[ "$user" != 'root' ] && your_user="$user"
+			echo
+			echo 'If you would like to use Docker as a non-root user, you should now consider'
+			echo 'adding your user to the "docker" group with something like:'
+			echo
+			echo '  sudo usermod -aG docker' $your_user
+			echo
+			echo 'Remember that you will have to log out and back in for this to take effect!'
+			echo
+			exit 0
+			;;
+
+		gentoo)
+			if [ "$url" = "https://test.docker.com/" ]; then
+				echo >&2
+				echo >&2 '  You appear to be trying to install the latest nightly build in Gentoo.'
+				echo >&2 '  The portage tree should contain the latest stable release of Docker, but'
+				echo >&2 '  if you want something more recent, you can always use the live ebuild'
+				echo >&2 '  provided in the "docker" overlay available via layman.  For more'
+				echo >&2 '  instructions, please see the following URL:'
+				echo >&2 '	https://github.com/tianon/docker-overlay#using-this-overlay'
+				echo >&2 '  After adding the "docker" overlay, you should be able to:'
+				echo >&2 '	emerge -av =app-emulation/docker-9999'
+				echo >&2
+				exit 1
+			fi
 
-    https://docs.docker.com/en/latest/installation/
+			(
+				set -x
+				$sh_c 'sleep 3; emerge app-emulation/docker'
+			)
+			exit 0
+			;;
+	esac
+
+	echo >&2
+	echo >&2 'Either your platform is not easily detectable, is not supported by this'
+	echo >&2 'installer script (yet - PRs welcome! [hack/install.sh]), or does not yet have'
+	echo >&2 'a package for Docker.  Please visit the following URL for more detailed'
+	echo >&2 'installation instructions:'
+	echo >&2
+	echo >&2 ' https://docs.docker.com/en/latest/installation/'
+	echo >&2
+    exit 1
+}
 
-EOF
+do_docker_install
 exit 1