ci: enable bazel remote caching on CircleCI (#21784)

This should cause Bazel builds to be incremental, only re-building parts of Angular affected by changes since the last build.
It also fixes a potential version skew, where CI was running the Bazel linter binaries in the ngcontainer docker image, but developers built them using the versions in WORKSPACE

PR Close #21784

.circleci/bazel.rc

@@ -0,0 +1,25 @@
+# These options are enabled when running on CI
+# We do this by copying this file to /etc/bazel.bazelrc at the start of the build.
+# See remote cache documentation in /docs/BAZEL.md
+
+# Don't be spammy in the logs
+build --noshow_progress
+
+# Don't run manual tests
+test --test_tag_filters=-manual
+
+# Enable experimental CircleCI bazel remote cache proxy
+# See remote cache documentation in /docs/BAZEL.md
+build --experimental_remote_spawn_cache --remote_rest_cache=http://localhost:7643
+
+# Prevent unstable environment variables from tainting cache keys
+build --experimental_strict_action_env
+
+# Workaround https://github.com/bazelbuild/bazel/issues/3645
+# Bazel doesn't calculate the memory ceiling correctly when running under Docker.
+# Limit Bazel to consuming resources that fit in CircleCI "medium" class which is the default:
+# https://circleci.com/docs/2.0/configuration-reference/#resource_class
+build --local_resources=3072,2.0,1.0
+
+# Retry in the event of flakes, eg. https://circleci.com/gh/angular/angular/31309
+test --flaky_test_attempts=2

.circleci/config.yml

@@ -15,6 +15,13 @@
 var_1: &docker_image angular/ngcontainer:0.1.0
 var_2: &cache_key angular-{{ .Branch }}-{{ checksum "yarn.lock" }}-0.1.0
 
+# See remote cache documentation in /docs/BAZEL.md
+var_3: &setup-bazel-remote-cache
+  run:
+    name: Start up bazel remote cache proxy
+    command: ~/bazel-remote-proxy -backend circleci://
+    background: true
+
 # Settings common to each job
 anchor_1: &job_defaults
   working_directory: ~/ng
@@ -34,14 +41,16 @@ jobs:
     steps:
       - checkout:
           <<: *post_checkout
-      # Check BUILD.bazel formatting before we have a node_modules directory
-      # Then we don't need any exclude pattern to avoid checking those files
-      - run: 'buildifier -mode=check $(find . -type f \( -name BUILD.bazel -or -name BUILD \)) ||
-              (echo "BUILD files not formatted. Please run ''yarn buildifier''" ; exit 1)'
-      # Run the skylark linter to check our Bazel rules
-      - run: 'find . -type f -name "*.bzl" |
-              xargs java -jar /usr/local/bin/Skylint_deploy.jar ||
+      # See remote cache documentation in /docs/BAZEL.md
+      - run: .circleci/setup_cache.sh
+      - run: sudo cp .circleci/bazel.rc /etc/bazel.bazelrc
+      - *setup-bazel-remote-cache
+
+      - run: 'yarn buildifier -mode=check ||
+              (echo -e "\nBUILD files not formatted. Please run ''yarn buildifier''" ; exit 1)'
+      - run: 'yarn skylint ||
               (echo -e "\n.bzl files have lint errors. Please run ''yarn skylint''"; exit 1)'
+
       - restore_cache:
           key: *cache_key
 
@@ -54,6 +63,11 @@ jobs:
     steps:
       - checkout:
           <<: *post_checkout
+      # See remote cache documentation in /docs/BAZEL.md
+      - run: .circleci/setup_cache.sh
+      - run: sudo cp .circleci/bazel.rc /etc/bazel.bazelrc
+      - *setup-bazel-remote-cache
+
       - restore_cache:
           key: *cache_key
 
@@ -62,7 +76,7 @@ jobs:
       # Use bazel query so that we explicitly ask for all buildable targets to be built as well
       # This avoids waiting for a build command to finish before running the first test
       # See https://github.com/bazelbuild/bazel/issues/4257
-      - run: bazel query --output=label '//modules/... union //packages/... union //tools/...' | xargs bazel test --config=ci
+      - run: bazel query --output=label '//modules/... union //packages/... union //tools/...' | xargs bazel test
 
       # CircleCI will allow us to go back and view/download these artifacts from past builds.
       # Also we can use a service like https://buildsize.org/ to automatically track binary size of these artifacts.

.circleci/setup_cache.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+# Install bazel remote cache proxy
+# This is temporary until the feature is no longer experimental on CircleCI.
+# See remote cache documentation in /docs/BAZEL.md
+
+set -u -e
+
+readonly DOWNLOAD_URL="https://5-116431813-gh.circle-artifacts.com/0/pkg/bazel-remote-proxy-$(uname -s)_$(uname -m)"
+
+curl --fail -o ~/bazel-remote-proxy "$DOWNLOAD_URL"
+chmod +x ~/bazel-remote-proxy