Add auto-update script

Signed-off-by: Knut Ahlers <knut@ahlers.me>

update-version.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+set -euo pipefail
+
+### ---- ###
+
+echo "Switch back to master"
+git checkout master
+git reset --hard origin/master
+
+### ---- ###
+
+version=$(curl -s "https://lv.luzifer.io/v1/catalog/code-server/latest/version")
+grep -q "CODE_SERVER_VERSION=${version} " Dockerfile && exit 0 || echo "Update required"
+
+sed -Ei \
+  -e "s/CODE_SERVER_VERSION=[0-9.]+/CODE_SERVER_VERSION=${version}/" \
+  Dockerfile
+
+### ---- ###
+
+echo "Testing build..."
+docker build .
+
+### ---- ###
+
+echo "Updating repository..."
+git add Dockerfile
+git -c user.name='Luzifer.io Jenkins' -c user.email='jenkins@luzifer.io' \
+  commit -m "Code-Server ${version}"
+git tag ${version}
+
+git push -q https://${GH_USER}:${GH_TOKEN}@github.com/luzifer-docker/code-server master --tags