Fix #15, WAL in archive mode when backup is off

WAL logs in archive mode will consume a lot more spaces and not useful
when backup is off. This fix add ability to switch WAL logs mode based
on the backup switch.

db/docker-entrypoint1.sh

@@ -1,5 +1,17 @@
 #!/bin/bash
 
+# if wal backup is not enabled, use minimal wal logging to reduce disk space
+: ${WAL_LEVEL:=minimal}
+: ${ARCHIVE_MODE:=off}
+# PGDATA is defined in upstream postgres dockerfile
+
+function update_conf () {
+    if [ -f $PGDATA/postgresql.conf ]; then
+        sed -i "s/wal_level =.*$/wal_level = $WAL_LEVEL/g" $PGDATA/postgresql.conf
+        sed -i "s/archive_mode =.*$/archive_mode = $ARCHIVE_MODE/g" $PGDATA/postgresql.conf
+    fi
+}
+
 if [ "${1:0:1}" = '-'  ]; then
     set -- postgres "$@"
 fi
@@ -10,6 +22,7 @@ if [ "$1" = 'postgres'  ]; then
     for v in ${VARS[@]}; do
         if [ "${!v}" = "" ]; then
             echo "$v is required for Wal-E but not set. Skipping Wal-E setup."
+            update_conf
             . /docker-entrypoint.sh
             exit
         fi
@@ -23,7 +36,9 @@ if [ "$1" = 'postgres'  ]; then
     done
     chown -R root:postgres /etc/wal-e.d
 
+    WAL_LEVEL=archive
+    ARCHIVE_MODE=on
+
+    update_conf
     . /docker-entrypoint.sh
 fi
-
-exec "$@"