Refactor new --sshcopyid behavior into separate cmdline option --sshc…

…opyauth

Related to commit 07e835e and the discussion within
#153

If execution of --sshcopyid fails, then user might want to be aware of
it. So instead of implementing the copying of .ssh/authorized_keys as
fallback of --sshcopyid, let's provide it via cmdline option
--sshcopyauth.

Reviewed-by: Chris Hofstaedtler
Reviewed-by: Darshaka Pathirana
Closes: #153

grml-debootstrap

@@ -155,6 +155,7 @@ Configuration options:
       --hostname <name>    Hostname of Debian system.
       --nopassword         Do not prompt for the root password.
       --password <pwd>     Use specified password as password for user root.
+      --sshcopyauth        Use ${HOME}/.ssh/authorized_keys to authorise root login on the target system.
       --sshcopyid          Use locally available public keys to authorise root login on the target system.
       --bootappend <line>  Add specified appendline to kernel whilst booting.
       --chroot-scripts <d> Execute chroot scripts from specified directory.
@@ -343,7 +344,7 @@ fi
 # }}}
 
 # cmdline handling {{{
-CMDLINE_OPTS=mirror:,iso:,release:,target:,mntpoint:,debopt:,defaultinterfaces,interactive,nodebootstrap,nointerfaces,nokernel,nopackages,filesystem:,config:,confdir:,packages:,chroot-scripts:,scripts:,post-scripts:,pre-scripts:,debconf:,vm,vmfile,vmsize:,keep_src_list,hostname:,password:,nopassword,grmlrepos,backportrepos,bootappend:,grub:,efi:,arch:,insecure,verbose,help,version,force,debug,contrib,non-free,remove-configs,sshcopyid
+CMDLINE_OPTS=mirror:,iso:,release:,target:,mntpoint:,debopt:,defaultinterfaces,interactive,nodebootstrap,nointerfaces,nokernel,nopackages,filesystem:,config:,confdir:,packages:,chroot-scripts:,scripts:,post-scripts:,pre-scripts:,debconf:,vm,vmfile,vmsize:,keep_src_list,hostname:,password:,nopassword,grmlrepos,backportrepos,bootappend:,grub:,efi:,arch:,insecure,verbose,help,version,force,debug,contrib,non-free,remove-configs,sshcopyid,sshcopyauth
 
 _opt_temp=$(getopt --name grml-debootstrap -o +m:i:r:t:p:c:d:vhV --long \
   $CMDLINE_OPTS -- "$@")
@@ -460,6 +461,9 @@ while :; do
   --sshcopyid)         # Use locally available public keys to authorise root login on the target system
     _opt_sshcopyid=T
     ;;
+  --sshcopyauth)       # Use .ssh/authorized_keys to authorise root login on the target system
+    _opt_sshcopyauth=T
+    ;;
   --grmlrepos)         # Enable Grml repository
     _opt_grmlrepos=T
     ;;
@@ -561,6 +565,7 @@ done
 [ "$_opt_nointerfaces" ]        && NOINTERFACES="true"
 [ "$_opt_nokernel" ]            && NOKERNEL="true"
 [ "$_opt_sshcopyid" ]           && SSHCOPYID="true"
+[ "$_opt_sshcopyauth" ]         && SSHCOPYAUTH="true"
 [ "$_opt_bootappend" ]          && BOOT_APPEND=$_opt_bootappend
 [ "$_opt_grub" ]                && GRUB=$_opt_grub
 [ "$_opt_efi" ]                 && EFI=$_opt_efi
@@ -589,6 +594,12 @@ if [ "$_opt_grub" ] && [ "$_opt_vmfile" ] ; then
   bailout 1
 fi
 
+if [ "${_opt_sshcopyid}" ] && [ "${_opt_sshcopyauth}" ] ; then
+  eerror "The --sshcopyid option is incompatible with --sshcopyauth, please drop either of them from your command line."
+  eend 1
+  bailout 1
+fi
+
 if [ -n "$ISO" ] && [[ "$DEBOOTSTRAP" =~ mmdebstrap$ ]] ; then
   eerror "The ISO option is incompatible with usage of mmdebstrap for bootstrapping."
   eerror "Either drop the --iso ... option or use plain debootstrap instead."
@@ -1810,7 +1821,28 @@ iface ${interface} inet dhcp
         bailout 1
       fi
     else
-      eerror "Could not open a connection to your authentication agent or the agent has no identites."
+      eerror "Error: Could not open a connection to your authentication agent or the agent has no identities."
+      eend 1
+      bailout 1
+    fi
+  fi
+
+  if [ -n "${SSHCOPYAUTH}" ] ; then
+    AUTHORIZED_KEYS_SOURCE=${AUTHORIZED_KEYS_SOURCE:-${HOME}/.ssh/authorized_keys}
+
+    if ! [ -f "${AUTHORIZED_KEYS_SOURCE}" ]; then
+      eerror "Error: could not read '${AUTHORIZED_KEYS_SOURCE}' for setting up SSH key login."
+      eend 1
+      bailout 1
+    fi
+
+    AUTHORIZED_KEYS_TARGET="${MNTPOINT}/root/.ssh/"
+    einfo "Copying '${AUTHORIZED_KEYS_SOURCE}' to '${AUTHORIZED_KEYS_TARGET}' as requested via --sshcopyauth option."
+    mkdir -m 0700 -p "${AUTHORIZED_KEYS_TARGET}"
+    if cp "${AUTHORIZED_KEYS_SOURCE}" "${AUTHORIZED_KEYS_TARGET}" ; then
+      eend 0
+    else
+      eerror "Error: copying '${AUTHORIZED_KEYS_SOURCE}' to '${AUTHORIZED_KEYS_TARGET}' failed."
       eend 1
       bailout 1
     fi

grml-debootstrap.8.txt

@@ -226,6 +226,13 @@ Options and environment variables
     Delete grml-debootstrap configuration files (/etc/debootstrap/*) from installed
     system. Useful for reproducible builds or if you don't want to leak information.
 
+*--sshcopyauth*::
+
+    Use locally available _$HOME/.ssh/authorized_keys_ to authorise root login on the target system.
+    This installs _$HOME/.ssh/authorized_keys_ as _/root/.ssh/authorized_keys_ on
+    the target system. If a different file than _$HOME/.ssh/authorized_keys_ should
+    be used, the environment variable _AUTHORIZED_KEYS_SOURCE_ can be used.
+
 *--sshcopyid*::
 
     Use locally available public keys to authorise root login on the target system.