Bazel cache for travis (#236)

* use google cloud storage for remote caching

* install gcloud

* poke readme to kick travis

* Remove cache thing

* unpoke README

* remove tabs from copy paste

* fix more tabs... what happened?

* fix formatting i think

* parsable yml

* try to cache the cloud sdk tools

* add gcloud to path

* dont need gcloud

* move service account to home directory

* lets try tmp directory


Former-commit-id: 0e844dc112bf6a78e0f3c24eb1ca4ce1ba4f376a [formerly c8106e91a46e7db40710f637bab3658fa9686cc4]
Former-commit-id: f9c69ca80a9a110568bf932eb913f3408f953e56

.travis-bazelrc

@@ -1,15 +1,17 @@
-# TODO: Set up remote caching.
-
 startup --host_jvm_args=-Xmx500m --host_jvm_args=-Xms500m
 
 # Disable sandboxing since it may fail inside of Travis' containers because the
 # mount system call is not permitted.
 build --spawn_strategy=standalone --genrule_strategy=standalone
 
+# Remote caching over Google Cloud Storage
+build --remote_http_cache=https://storage.googleapis.com/prysmatic-bazel-cache 
+build --google_credentials=/tmp/service-account.json
+
 # Set some build options for travis container.
 build --local_resources=1536,1.5,0.5
 build --noshow_progress
 build --verbose_failures 
 build --sandbox_debug
 build --test_output=errors
-build --flaky_test_attempts=5
+build --flaky_test_attempts=5

.travis.yml

@@ -13,6 +13,7 @@ matrix:
     - os: linux
       env: V=0.15.0
       before_install:
+        # Install Bazel
         - |
           if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
             OS=darwin
@@ -40,6 +41,9 @@ matrix:
           chmod +x install.sh
           ./install.sh --user
           rm -f install.sh
+        # Decrypt service account
+        - openssl aes-256-cbc -K $encrypted_64ca747eb448_key -iv $encrypted_64ca747eb448_iv
+          -in service-account.json.enc -out /tmp/service-account.json -d
       
       install: true # Skip install go packages.