.travis.yml: Enable Docker buildkit

.travis.yml

@@ -1,15 +1,29 @@
+dist: bionic
 language: go
-services:
-  - docker
 go:
   - "1.14"
+
 env:
-  - "GO15VENDOREXPERIMENT=1"
+  global:
+    - "GO15VENDOREXPERIMENT=1"
+    - "DOCKER_BUILDKIT=1"
 before_install:
+  - sudo rm -rf /var/lib/apt/lists/*
+  - curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+  - sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) edge"
+  - sudo apt-get update
+  - echo '{"experimental":true}' | sudo tee /etc/docker/daemon.json
+  - export DOCKER_CLI_EXPERIMENTAL=enabled
+  - sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce
+  - mkdir -vp ~/.docker/cli-plugins/
+  - curl --silent -L "https://github.com/docker/buildx/releases/download/v0.3.0/buildx-v0.3.0.linux-amd64" > ~/.docker/cli-plugins/docker-buildx
+  - chmod a+x ~/.docker/cli-plugins/docker-buildx
+  - docker buildx version
   - sudo -E env "PATH=$PATH" apt-get install -y libcap2-bin
   - sudo -E env "PATH=$PATH" make deps
 script:
   - sudo -E env "PATH=$PATH" make multiarch-build test-integration test-coverage
+
 #after_success:
 #  - |
 #      if [ -n "$TRAVIS_TAG" ] && [ "$TRAVIS_PULL_REQUEST" == "false" ]; then