Add Drone CI caching

scripts/cacher.sh

@@ -0,0 +1,53 @@
+#!/usr/bin/env sh
+# cacher.sh -- Restore and rebuild cache.
+# Cache paths are designed to work with multi-arch builds and are organized
+# based on the branch or tag. The master branch cache is used as a fallback.
+# This will download and package the cache but it will not upload it.
+
+set -eu
+
+# Try restoring from each argument in turn until we get something.
+restore() {
+	for branch in "$@" ; do
+		if [ -n "$branch" ] ; then
+			cache_path="https://codesrv-ci.cdr.sh/cache/$branch/$tar.tar.gz"
+			if wget "$cache_path" ; then
+				tar xzvf "$tar.tar.gz"
+				break
+			fi
+		fi
+	done
+}
+
+# We need to cache the built-in extensions and Node modules. Everything inside
+# the cache-upload directory will be uploaded as-is to the code-server bucket.
+package() {
+	mkdir -p "cache-upload/cache/$1"
+	tar czfv "cache-upload/cache/$1/$tar.tar.gz" node_modules source/vscode-1.41.1-source
+}
+
+main() {
+	cd "$(dirname "$0")/.."
+
+	# Get the branch for this build.
+	branch=${DRONE_BRANCH:-${DRONE_SOURCE_BRANCH:-${DRONE_TAG:-}}}
+
+	# The cache will be named based on the arch, platform, and libc.
+	arch=$DRONE_STAGE_ARCH
+	platform=${PLATFORM:-linux}
+	case $DRONE_STAGE_NAME in
+		*alpine*) libc=musl  ;;
+		*       ) libc=glibc ;;
+	esac
+
+	tar="$platform-$arch-$libc"
+
+	# The action is determined by the name of the step.
+	case $DRONE_STEP_NAME in
+		*restore*) restore "$branch" "$DRONE_REPO_BRANCH" ;;
+		*rebuild*|*package*) package "$branch" ;;
+		*) exit 1 ;;
+	esac
+}
+
+main "$@"