diff --git a/scripts/_common.sh b/scripts/_common.sh
index b4bb1eb..d8051ab 100644
--- a/scripts/_common.sh
+++ b/scripts/_common.sh
@@ -12,3 +12,37 @@ ynh_delete_file_checksum () {
 	local checksum_setting_name=checksum_${1//[\/ ]/_}	# Replace all '/' and ' ' by '_'
 	ynh_app_setting_delete $app $checksum_setting_name
 }
+
+# =============================================================================
+# COMMON ROUNDCUBE FUNCTIONS
+# =============================================================================
+
+# Execute a composer command from a given directory
+# usage: composer_exec workdir COMMAND [ARG ...]
+exec_composer() {
+  local workdir=$1
+  shift 1
+
+  COMPOSER_HOME="${workdir}/.composer" \
+    php "${workdir}/composer.phar" $@ \
+      -d "${workdir}" --quiet --no-interaction
+}
+
+# Install and initialize Composer in the given directory
+# usage: init_composer destdir
+init_composer() {
+  local destdir=$1
+
+  # install composer
+  curl -sS https://getcomposer.org/installer \
+    | COMPOSER_HOME="${destdir}/.composer" \
+        php -- --quiet --install-dir="$destdir" \
+    || ynh_die "Unable to install Composer"
+
+  # install composer.json
+  cp "${destdir}/composer.json-dist" "${destdir}/composer.json"
+
+  # update dependencies to create composer.lock
+  exec_composer "$destdir" install --no-dev \
+    || ynh_die "Unable to update Roundcube core dependencies"
+}