Migration scripts infrastructure.

Some changes require manual action, like those affecting what is run
only during installation. It'd be nice if we had something for that
similar to what flyway does for the DB changes.

scripts/install/install.sh

@@ -286,6 +286,10 @@ if [ ! -f "${basedir}"/publite2/settings.ini ]; then
   cp "${basedir}"/publite2/settings.ini{.dist,}
 fi
 
+cd "${basedir}"/scripts/migration
+mig_scripts=([0-9]*)
+echo "${mig_scripts[-1]}" > checkpoint
+
 cd "${basedir}"/scripts && ./sync-js-hand.sh
 cd "${basedir}"/freeciv-web && ./build.sh
 

scripts/migration/.gitignore

@@ -0,0 +1 @@
+checkpoint

scripts/migration/README.md

@@ -0,0 +1,14 @@
+Migration scripts
+-----------------
+
+When changes in Freeciv-web may make current installations stop working, a
+migration script should be provided to help users find and understand the
+changeset, and hopefully migrate their installation with no issues if it's
+a default setup.
+
+The filenames start with a sequential four-digit number. When `migrate.sh`
+is executed it runs each of them in order, following from where it stopped
+in its last execution.
+
+The scripts may still fail on purpose if manual action is required (or safer
+than trying to script it).

scripts/migration/migrate.sh

@@ -0,0 +1,55 @@
+#!/bin/bash
+
+#   Copyright (C) 2018  The Freeciv-web project
+#
+#   This program is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU Affero General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU Affero General Public License for more details.
+#
+#   You should have received a copy of the GNU Affero General Public License
+#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Runs new migration scripts.
+# migrate.sh [migration_dir]
+#
+# Every file in migration_dir starting with a number is run in lexicographical
+# order, except the ones lower than or equal to the saved checkpoint.
+
+set -e
+
+if [ -z "$1" ]; then
+  BASEDIR=${BASH_SOURCE%/*}
+else
+  BASEDIR=$1
+fi
+
+if [ -z "${BASEDIR}" ]; then
+  echo >&2 "Please pass the directory with the migration scripts"
+  exit 1
+fi
+
+if [ "${BASEDIR:0:1}" = - ]; then
+  BASEDIR=./"${BASEDIR}"
+fi
+
+cd "${BASEDIR}"
+
+if [ -f checkpoint ]; then
+  read LAST < checkpoint
+fi
+
+for f in [0-9]*; do
+  if [ "$f" \> "${LAST}" ]; then
+    echo "Running $f"
+    ./"$f"
+    echo "$f" > checkpoint
+  fi
+done
+
+echo "Migration finished"