diff --git a/Dockerfile b/Dockerfile
index d41fd2b..e9095d0 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,8 @@
-FROM ubuntu:18.04
+FROM ubuntu:20.04
 
+ARG docker_version="19.03.12"
+
+ENV DEBIAN_FRONTEND=noninteractive
 RUN apt-get update \
     && apt-get install -y --no-install-recommends apt-transport-https \
                ca-certificates curl software-properties-common gnupg dirmngr \
@@ -7,7 +10,10 @@ RUN apt-get update \
     && add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
                           $(lsb_release -cs) stable" \
     && apt-get update \
-    && apt-get install -y --no-install-recommends ufw "docker-ce=18.06.1~*" \
+    && apt-get install -y --no-install-recommends locales ufw \
+    && ( apt-get install -y --no-install-recommends "docker-ce=5:${docker_version}~*" || \
+         apt-get install -y --no-install-recommends "docker-ce=${docker_version}~*" ) \
+    && locale-gen en_US.UTF-8 \
     && apt-get clean autoclean \
     && apt-get autoremove --yes \
     && rm -rf /var/lib/{apt,dpkg,cache,log}/
diff --git a/Vagrantfile b/Vagrantfile
index 877efb6..1499184 100644
--- a/Vagrantfile
+++ b/Vagrantfile
@@ -6,6 +6,7 @@
 Vagrant.configure('2') do |config|
 
   config.vm.box = "chaifeng/ubuntu-20.04-docker-19.03.11"
+  #config.vm.box = "chaifeng/ubuntu-16.04-docker-18.03"
 
   config.vm.provider 'virtualbox' do |vb|
     vb.memory = '1024'
@@ -112,10 +113,10 @@ DOCKERFILE
 
     master.vm.provision "local-webapp", type: 'shell', inline: <<-SHELL
         set -euo pipefail
-        for name in public:8080 local:8000; do
+        for name in public:18080 local:8000; do
             webapp="${name%:*}_webapp"
             port="${name#*:}"
-            if docker inspect "$webapp" &>/dev/null; then docker stop "$webapp"; fi
+            if docker inspect "$webapp" &>/dev/null; then docker rm -f "$webapp"; fi
             docker run -d --restart unless-stopped --name "$webapp" \
                 -p "$port:80" --env name="$webapp" #{private_registry}/chaifeng/hostname-webapp
             sleep 1
@@ -126,7 +127,7 @@ DOCKERFILE
 
     master.vm.provision "swarm-webapp", type: 'shell', inline: <<-SHELL
       set -euo pipefail
-        for name in public:9090 local:9000; do
+        for name in public:29090 local:9000; do
             webapp="${name%:*}_service"
             port="${name#*:}"
             if docker service inspect "$webapp" &>/dev/null; then docker service rm "$webapp"; fi
@@ -162,10 +163,10 @@ DOCKERFILE
         set -x
         server="http://#{ip_prefix}.130"
         function test-webapp() { timeout 3 curl --silent "$@"; }
-        test-webapp "$server:8080"
+        test-webapp "$server:18080"
         ! test-webapp "$server:8000"
 
-        test-webapp "$server:9090"
+        test-webapp "$server:29090"
         ! test-webapp "$server:9000"
 
         echo "====================="