feat: implement the traefik plugin

This plugin uses a docker-compose based Traefik installation in conjunction with injected container labels to route requests. It only exposes the minimal necessary for routing traffic to docker containers. Users wishing to customize further labels may explore using the docker-options plugin to attach additional labels during the 'deploy' phase.

plugins/traefik-vhosts/install

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+source "$PLUGIN_CORE_AVAILABLE_PATH/common/property-functions"
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+
+trigger-traefik-install() {
+  declare desc="installs the traefik plugin"
+  declare trigger="install"
+
+  mkdir -p "${DOKKU_LIB_ROOT}/data/traefik"
+  chown -R "${DOKKU_SYSTEM_USER}:${DOKKU_SYSTEM_GROUP}" "${DOKKU_LIB_ROOT}/data/traefik"
+
+  fn-plugin-property-setup "traefik"
+}
+
+trigger-traefik-install "$@"