#!/bin/bash
# A script which runs, largely on the remote machine, to prepare for backup
# Jobs to do: 
# * Exclude files which are only found in packages
# * List all packages which are installed
# * (optionally) dump MySQL into a file
# * (optionally) dump PostgreSQL into a file
CONFDIR=/etc/chem-zfs-backup-server/zfs-rsync.d
SSH="ssh -p ${SSHPORT:-22} -o ConnectTimeout=10"
SCP="scp -P ${SSHPORT:-22}"

set -xv

SERVER=$1
if [ -z $SERVER ] ; then
 echo $0 Server
 exit 1
fi
(
set -e
# Has the package status changed since last time we generated the list of files?
if $SSH root@$SERVER [ /var/lib/dpkg/status -nt /var/adm/backup/package-files ] ; then
 # Need to rebuild package-files
 $SSH root@$SERVER "
  set -e
  set -o pipefail
  umask 077
  FILELIST=\`tempfile\`
  CONFLIST=\`tempfile\`
  DIFFLIST=\'tempfile\'
  mkdir -p /var/adm/backup
  # Which packages are installed?
  dpkg --get-selections | awk ' { print \$1 ; } ' >/var/adm/backup/packages
  cat /var/lib/dpkg/info/*.list | while read F ; do [ -f \"\$F\" ] && echo \"\$F\" ; done | sort > \$FILELIST
  awk '/Description:/ { flag = 0 } ; flag == 1 { print \$1 ; }  ; /Conffiles:/ { flag = 1  } ; ' </var/lib/dpkg/status |  sort >\$CONFLIST
  # ignore the fact that diff exits non-zero when differences are found
  set +e
  diff -u \$FILELIST \$CONFLIST  > \$DIFFLIST
  set -e
  cat \$DIFFLIST | grep ^-/ | sed s/^-// | tr '\\n' '\\0' | xargs -n1 -0 realpath >/var/adm/backup/package-files
  rm \$FILELIST \$CONFLIST \$DIFFLIST
 "
 mkdir -p $CONFDIR/$SERVER
 $SCP -q root@$SERVER:/var/adm/backup/package-files $CONFDIR/$SERVER/exclude
fi
# Ensure that the excludes file exists, even if we haven't updated it this time
if [ ! -f $CONFDIR/$SERVER/exclude ] ; then
  mkdir -p $CONFDIR/$SERVER
 $SCP -q root@$SERVER:/var/adm/backup/package-files $CONFDIR/$SERVER/exclude
fi

# If we can identify this as a xen VM, add some extra dirs to the exclude list
# because they include some files built by the kernel package but are not
# provided by it.
# systemd-detect-virt is present on all our Ubuntu VMs so is hopefully a 
# reliable method to use
# NB this returns non-zero on a non-virtual machine so we don't mind
# the return value
set +e
VIRT_TYPE=$(ssh root@$SERVER systemd-detect-virt 2>/dev/null)
set -e
if [ "$VIRT_TYPE" == "xen" ] ; then
cat<<EOF >> $CONFDIR/$SERVER/exclude
/lib/modules
/lib/firmware
EOF
fi

if $SSH root@$SERVER id postgres >/dev/null 2>&1 ; then
  PGVER=$($SSH root@$SERVER pg_lsclusters| awk -F '[. ]+' '/online/ { print $1 }')
  if [[ -n "$PGVER" ]]; then
    if (( "$PGVER" >= 12 )) ; then
      $SSH root@$SERVER "umask 077; su -c 'pg_dumpall --clean' postgres |gzip -9 >/var/adm/backup/postgres" || echo Postgres failed on $SERVER
    else
      $SSH root@$SERVER "umask 077; su -c 'pg_dumpall --oids --clean' postgres |gzip -9 >/var/adm/backup/postgres" || echo Postgres failed on $SERVER
    fi
  fi
fi

$SSH root@$SERVER "
set -e
# Ensure that things are not readable where they ought not to be
umask 077

# Save the package configuration info
which debconf-get-selections >/dev/null 2>&1 || apt-get install debconf-utils
which rsync >/dev/null 2>&1 || apt-get install rsync
debconf-get-selections  >/var/adm/backup/debconf

# Dump MySQL, if the root user has access
set +e
systemctl is-enabled mysql --quiet 2>/dev/null
MYSQL_ENABLED=\$?
set -e

if [ \$MYSQL_ENABLED -eq 0 ] ; then
  if [ -f /root/.my.cnf ] ; then
    DEFAULTS_FILE=/root/.my.cnf
  else
    DEFAULTS_FILE=/etc/mysql/debian.cnf
  fi
  mysqldump  --defaults-file=\$DEFAULTS_FILE --all-databases >/var/adm/backup/mysql
fi

"
echo Prepared $SERVER `date`
) >/var/log/chem-zfs-backup-server/${SERVER}-prepare 2>&1