Add -f option to avoid ln cmd failing when target exist

If we run ./stack.sh again in the same host, test-setup.sh will fail,
because go and gofmt link have existed in the host, ln command will
throw error, like this:

ln: failed to create symbolic link '/usr/local/bin/gofmt': File exists

Author: kiwik

devstack/plugin.sh

@@ -90,11 +90,11 @@ function install_k8s_cloud_provider {
     # Seed the log files so devstack-gate can capture the logs
     export LOG_DIR=${SCREEN_LOGDIR:-/opt/stack/logs}
     sudo mkdir -p $LOG_DIR
-    sudo touch $LOG_DIR/kube-apiserver.log;sudo ln -s $LOG_DIR/kube-apiserver.log $LOG_DIR/screen-kube-apiserver.log
-    sudo touch $LOG_DIR/kube-controller-manager.log;sudo ln -s $LOG_DIR/kube-controller-manager.log $LOG_DIR/screen-kube-controller-manager.log
-    sudo touch $LOG_DIR/kube-proxy.log;sudo ln -s $LOG_DIR/kube-proxy.log $LOG_DIR/screen-kube-proxy.log
-    sudo touch $LOG_DIR/kube-scheduler.log;sudo ln -s $LOG_DIR/kube-scheduler.log $LOG_DIR/screen-kube-scheduler.log
-    sudo touch $LOG_DIR/kubelet.log;sudo ln -s $LOG_DIR/kubelet.log $LOG_DIR/screen-kubelet.log
+    sudo touch $LOG_DIR/kube-apiserver.log;sudo ln -sf $LOG_DIR/kube-apiserver.log $LOG_DIR/screen-kube-apiserver.log
+    sudo touch $LOG_DIR/kube-controller-manager.log;sudo ln -sf $LOG_DIR/kube-controller-manager.log $LOG_DIR/screen-kube-controller-manager.log
+    sudo touch $LOG_DIR/kube-proxy.log;sudo ln -sf $LOG_DIR/kube-proxy.log $LOG_DIR/screen-kube-proxy.log
+    sudo touch $LOG_DIR/kube-scheduler.log;sudo ln -sf $LOG_DIR/kube-scheduler.log $LOG_DIR/screen-kube-scheduler.log
+    sudo touch $LOG_DIR/kubelet.log;sudo ln -sf $LOG_DIR/kubelet.log $LOG_DIR/screen-kubelet.log
 
     echo "Stopping firewall and allow all traffic..."
     sudo iptables -F

tools/test-setup.sh

@@ -50,8 +50,8 @@ case $OS in
         fi
         sudo add-apt-repository --yes ppa:gophers/archive
         sudo apt-get update && sudo $APT_GET install golang-1.9-go
-        sudo ln -s /usr/lib/go-1.9/bin/go /usr/local/bin
-        sudo ln -s /usr/lib/go-1.9/bin/gofmt /usr/local/bin
+        sudo ln -sf /usr/lib/go-1.9/bin/go /usr/local/bin
+        sudo ln -sf /usr/lib/go-1.9/bin/gofmt /usr/local/bin
         wget -O install-glide.sh https://glide.sh/get
         export GOPATH=$HOME/go
         export PATH=$PATH:$HOME/go/bin