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
 
@@ -52,38 +67,47 @@ function pgsql.backup(){
 
   # prevent could not change directory to "/root": Permission denied
   (
-  cd /tmp
-
-  sSqlGetDblist="select datname from pg_database where not datistemplate and datallowconn order by datname;"
-  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}${DATABASE}"
-    OUTFILE="${BACKUP_TARGETDIR}/$(get_outfile ${DATABASE}).sql"
-
-    echo -n " snapshot ... "
-    # drop snapshot db first - just in case
-    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
-        echo -n "delete snapshot ... "
-        su ${PGUSER} -c "dropdb ${SNAPSHOTDB}"
+    cd /tmp
+
+    sSqlGetDblist="select datname from pg_database where not datistemplate and datallowconn order by datname;"
+    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 ... "
 
-        db._compressDumpfile "$OUTFILE"
+      SNAPSHOTDB="${DATABASE}"
+      test $bUseSnapshot -eq 1 && SNAPSHOTDB="${snapshotprefix}${DATABASE}"
+
+      OUTFILE="${BACKUP_TARGETDIR}/$(get_outfile ${DATABASE}).sql"
+
+      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
+          test $bUseSnapshot -eq 1 && su ${PGUSER} -c "dropdb ${SNAPSHOTDB}"
+        fi
       else
-        fetchrc
-        su ${PGUSER} -c "dropdb ${SNAPSHOTDB}"
+        cecho error "ERROR!"
       fi
-    else
-      cecho error "ERROR!"
-    fi
 
-  done
+    done
   )
 }