fixing CI build failed

.travis.yml

@@ -10,6 +10,11 @@ env:
     - PHP_VERSION=71
     - HUGO_VERSION=0.20.2
 
+# Installing a newer Docker version
+before_install:
+  - sudo apt-get update
+  - sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-engine
+
 script: ./travis-build.sh
 
 deploy:

travis-build.sh

@@ -3,6 +3,12 @@
 #### halt script on error
 set -e
 
+echo '##### Print docker version'
+docker --version
+
+echo '##### Print environment'
+env | sort
+
 #### Build the Docker Images
 if [ -n "${PHP_VERSION}" ]; then
     cp env-example .env