Add a mac-clean.sh script for manual regular maintenance.
diff --git a/mac/mac-clean.sh b/mac/mac-clean.sh
new file mode 100644
index 0000000..d96464c
--- /dev/null
+++ b/mac/mac-clean.sh
@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -eux
+
+sudo launchctl unload /Library/LaunchDaemons/jenkins.plist
+
+cd ~/
+rm -rf /var/tmp/_bazel_ci workspace android-ndk-* android-sdk-* node jenkins.slave.*.log slave.jar
+curl https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/mac/mac-android.sh | bash
+curl https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/mac/mac-nodejs.sh | bash
+curl -o slave.jar http://master.ci.bazel.io/jnlpJars/slave.jar
diff --git a/mac/mac-service.sh b/mac/mac-service.sh
index 466d90d..5dc794a 100644
--- a/mac/mac-service.sh
+++ b/mac/mac-service.sh
@@ -35,7 +35,7 @@
 export ANDROID_SDK_BUILD_TOOLS_VERSION=$(ls $ANDROID_SDK_PATH/build-tools | sort -n | tail -1)
 export ANDROID_SDK_API_LEVEL=$(ls $ANDROID_SDK_PATH/platforms | cut -d '-' -f 2 | sort -n | tail -1)
 export ANDROID_NDK_API_LEVEL=$(ls $ANDROID_NDK_PATH/platforms | cut -d '-' -f 2 | sort -n | tail -1)
-export PATH=/Users/ci/node/node-v6.9.1-darwin-x64/bin:$PATH
+export PATH=/Users/ci/node/node-v8.9.4-darwin-x64/bin:$PATH
 
 while true; do
   $(which java) -jar slave.jar -jnlpUrl https://ci.bazel.build/computer/$(cat $HOME/node_name)/slave-agent.jnlp -noReconnect