postgres - detect readonly instance

plugins/localdump/pgsql.sh

@@ -42,6 +42,21 @@ function pgsql.backup(){
   local SNAPSHOTDB
   local OUTFILE
   local snapshotprefix="snapshot_"
+  local bUseSnapshot
+
+  typeset -i bUseSnapshot=0
+
+  # Detect a readonly or writeable postgres host.
+  TESTDB="imlbackup_createtest"
+  su ${PGUSER} -c "dropdb ${TESTDB}" >/dev/null 2>&1
+  if su ${PGUSER} -c "psql ${BACKUP_PARAMS} -c \"CREATE DATABASE ${TESTDB};\"" >/dev/null 2>&1
+  then
+    bUseSnapshot=1
+    su ${PGUSER} -c "dropdb ${TESTDB}"
+    echo "INFO: enabling snapshots"
+  else
+    echo "INFO: create database failed for snapshots - dumping databases directly"
+  fi
 
   create_targetdir
 
@@ -58,26 +73,35 @@ function pgsql.backup(){
     for DATABASE in $( su ${PGUSER} -c "psql ${BACKUP_PARAMS} -At -c '$sSqlGetDblist' postgres" 2>/dev/null | grep -v "^$snapshotprefix" )
     do
       echo -n "__DB__${SERVICENAME} backup $DATABASE ... "
-    SNAPSHOTDB="${snapshotprefix}${DATABASE}"
+
+      SNAPSHOTDB="${DATABASE}"
+      test $bUseSnapshot -eq 1 && SNAPSHOTDB="${snapshotprefix}${DATABASE}"
+
       OUTFILE="${BACKUP_TARGETDIR}/$(get_outfile ${DATABASE}).sql"
 
-    echo -n " snapshot ... "
+      myrc=0
+
       # drop snapshot db first - just in case
+      test $bUseSnapshot -eq 1 && (
+        echo -n " snapshot ... "
         su ${PGUSER} -c "dropdb ${SNAPSHOTDB}" >/dev/null 2>&1
         su ${PGUSER} -c "psql ${BACKUP_PARAMS} -c \"CREATE DATABASE ${SNAPSHOTDB} WITH TEMPLATE ${DATABASE};\"" >/dev/null
         fetchrc >/dev/null
+      )
       if [ $myrc -eq 0 ]; then
 
         echo -n "backup ... "
         if su ${PGUSER} -c "pg_dump ${BACKUP_PARAMS} -Fp ${SNAPSHOTDB} >$OUTFILE"; then
           fetchrc >/dev/null
+          test $bUseSnapshot -eq 1 && ( 
             echo -n "delete snapshot ... "
             su ${PGUSER} -c "dropdb ${SNAPSHOTDB}"
+          )
 
           db._compressDumpfile "$OUTFILE"
         else
           fetchrc
-        su ${PGUSER} -c "dropdb ${SNAPSHOTDB}"
+          test $bUseSnapshot -eq 1 && su ${PGUSER} -c "dropdb ${SNAPSHOTDB}"
         fi
       else
         cecho error "ERROR!"