🏗 Use xenial VMs on Travis for faster bootup

.travis.yml

@@ -1,5 +1,5 @@
 language: node_js
-dist: trusty
+dist: xenial
 node_js:
   - "lts/*"
 python:
@@ -13,10 +13,10 @@ notifications:
   webhooks:
     - http://savage.nonblocking.io:8080/savage/travis
 before_install:
-  - curl -o- -L https://yarnpkg.com/install.sh | bash
-  - export PATH="$HOME/.yarn/bin:$HOME/.config/yarn/global/node_modules/.bin:$PATH"
-  - pip install urllib3[secure]
-  - pip install gsutil --user
+  - pip install --user gsutil protobuf urllib3[secure]
+  # Override Xenial's default Java version (github.com/travis-ci/travis-ci/issues/10290)
+  - export PATH=$(echo "$PATH" | sed -e 's/:\/usr\/local\/lib\/jvm\/openjdk11\/bin//')
+  - export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-amd64
 branches:
   only:
     - master
@@ -25,12 +25,16 @@ branches:
     - /^amp-release-.*$/
     - /^revert-.*$/
 addons:
+  apt:
+    packages:
+      - protobuf-compiler
+      - python-protobuf
+  chrome: stable
   hosts:
     - ads.localhost
     - iframe.localhost
-    # CURLs amp subdomain for amp-recaptcha-input,
-    # integration tests. The hash is the
-    # CURLS subdomain for localhost:9876
+    # CURLs amp subdomain for the amp-recaptcha-input integration test. The hash
+    # is the CURLS subdomain for localhost:9876
     - jgla3zmib2ggq5buc4hwi5taloh6jlvzukddfr4zltz3vay5s5rq.recaptcha.localhost
     # Requested by some tests because they need a valid font host,
     # but should not resolve in tests.
@@ -50,24 +54,15 @@ jobs:
         - node build-system/pr-check/checks.js
     - stage: build
       name: "Validator Tests"
-      before_script:
-        - pip install --user protobuf
       script:
         - node build-system/pr-check/validator-tests.js
-      addons:
-        apt:
-          packages:
-            - protobuf-compiler
-            - python-protobuf
     - stage: build
       name: "Dist"
       if: type != pull_request
       script:
         - node build-system/pr-check/dist.js
     - stage: test
       name: "Dist, Bundle Size, Single Pass Tests"
-      addons:
-        chrome: stable
       script:
         - node build-system/pr-check/dist-tests.js
     - stage: test
@@ -76,8 +71,6 @@ jobs:
         - node build-system/pr-check/visual-diff-tests.js
     - stage: test
       name: "Local Tests"
-      addons:
-        chrome: stable
       script:
         - node build-system/pr-check/local-tests.js
     - stage: test
@@ -87,18 +80,18 @@ jobs:
       after_script:
         - build-system/sauce_connect/stop_sauce_connect.sh
   fast_finish: true
-  #TODO(ampproject/wg-infra): remove when remote tests stabilize
+
+  # TODO(ampproject/wg-infra): remove when remote tests stabilize
   allow_failures:
-      - script:
-          - node build-system/pr-check/remote-tests.js
+    - script:
+      - node build-system/pr-check/remote-tests.js
 cache:
-  yarn: true
   directories:
-    - build-system/tasks/visual-diff/node_modules
     - node_modules
+    - build-system/tasks/visual-diff/node_modules
+    - sauce_connect
     - validator/node_modules
     - validator/nodejs/node_modules
     - validator/webui/node_modules
-    - sauce_connect
-  pip: true
-  bundler: true
+    - $HOME/.cache/pip
+  yarn: true