Add a script to read all databases with a prefix from the database server

When passing a value via the FOODSOFT_DB_PREFIX environment variable the
FOODSOFT_FOODCOOPS environment variable will be overwritten with a list
of databases starting with the given prefix.

This can be used to dynamically generate the app_config.yml in a multicoop
installation and avoid listing all instances manually.

docker-entrypoint.sh

@@ -6,6 +6,10 @@ if [ -f tmp/pids/server.pid ]; then
   rm tmp/pids/server.pid
 fi
 
+if [ ! -z "${FOODSOFT_DB_PREFIX}" ] || [ ! -z "${FOODSOFT_DB_PREFIX_FILE}" ]; then
+  FOODSOFT_FOODCOOPS=`BUNDLE_CONFIG=/dev/null bundle exec ruby script/list_databases`
+fi
+
 if [ -e app_config.defaults.yml ] ; then
   cat app_config.defaults.yml > config/app_config.yml
 

script/list_databases

@@ -0,0 +1,22 @@
+require 'mysql2'
+
+def get_env_or_file_content(name)
+  ENV.fetch('FOODSOFT_DB_' + name) do |full_name|
+    file_name = ENV.fetch(full_name + '_FILE', nil)
+    file_name ? File.read(file_name).strip : ''
+  end
+end
+
+prefix = get_env_or_file_content('PREFIX')
+host = get_env_or_file_content('HOST')
+database = get_env_or_file_content('NAME')
+username = get_env_or_file_content('USER')
+password = get_env_or_file_content('PASSWORD')
+
+client = Mysql2::Client.new(host: host, database: database, username: username, password: password)
+escaped_prefix = client.escape(prefix)
+results = client.query("SELECT schema_name FROM information_schema.schemata WHERE schema_name LIKE '#{escaped_prefix}%'")
+results.each do |row|
+  puts row["schema_name"][prefix.length..]
+end
+client.close