Add a feature flag for `bundle install` not `—cache`ing by default

7 files changed, 44 insertions, 11 deletions

diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index 1f01999ead..a79ebfcf15 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -163,8 +163,8 @@ module Bundler
       "Specify the number of jobs to run in parallel"
     method_option "local", :type => :boolean, :banner =>
       "Do not attempt to fetch gems remotely and use the gem cache instead"
-    method_option "no-cache", :type => :boolean, :banner =>
-      "Don't update the existing gem cache."
+    method_option "cache", :type => :boolean, :default => Bundler.feature_flag.install_caches_by_default?, :banner =>
+      "Update the existing gem cache."
     method_option "force", :type => :boolean, :banner =>
       "Force downloading every gem."
     method_option "no-prune", :type => :boolean, :banner =>
diff --git a/lib/bundler/cli/install.rb b/lib/bundler/cli/install.rb
index 0592385e23..404f7d5750 100644
--- a/lib/bundler/cli/install.rb
+++ b/lib/bundler/cli/install.rb
@@ -66,7 +66,7 @@ module Bundler
       definition.validate_runtime!
 
       installer = Installer.install(Bundler.root, definition, options)
-      Bundler.load.cache if Bundler.app_cache.exist? && !options["no-cache"] && !Bundler.settings[:frozen]
+      Bundler.load.cache if Bundler.app_cache.exist? && options["cache"] && !Bundler.settings[:frozen]
 
       Bundler.ui.confirm "Bundle complete! #{dependencies_count_for(definition)}, #{gems_installed_for(definition)}."
       Bundler::CLI::Common.output_without_groups_message
diff --git a/lib/bundler/feature_flag.rb b/lib/bundler/feature_flag.rb
index e901e047ed..c138930cdb 100644
--- a/lib/bundler/feature_flag.rb
+++ b/lib/bundler/feature_flag.rb
@@ -34,6 +34,7 @@ module Bundler
     settings_flag(:error_on_stderr) { bundler_2_mode? }
     settings_flag(:global_gem_cache) { bundler_2_mode? }
     settings_flag(:init_gems_rb) { bundler_2_mode? }
+    settings_flag(:install_caches_by_default) { !bundler_2_mode? }
     settings_flag(:lockfile_uses_separate_rubygems_sources) { bundler_2_mode? }
     settings_flag(:only_update_to_newer_versions) { bundler_2_mode? }
     settings_flag(:plugins) { @bundler_version >= Gem::Version.new("1.14") }
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index afea575bf6..8fefab848d 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -28,6 +28,7 @@ module Bundler
       global_gem_cache
       ignore_messages
       init_gems_rb
+      install_caches_by_default
       lockfile_uses_separate_rubygems_sources
       major_deprecations
       no_install
diff --git a/man/bundle-config.ronn b/man/bundle-config.ronn
index 785229e59a..a12d4d3608 100644
--- a/man/bundle-config.ronn
+++ b/man/bundle-config.ronn
@@ -222,16 +222,16 @@ learn more about their operation in [bundle install(1)][bundle-install].
 * `gem.push_key` (`BUNDLE_GEM__PUSH_KEY`):
    Sets the `--key` parameter for `gem push` when using the `rake release`
    command with a private gemstash server.
-* `error_on_stderr` (`BUNDLE_ERROR_ON_STDERR`)
+* `error_on_stderr` (`BUNDLE_ERROR_ON_STDERR`):
    Print Bundler errors to stderr.
-* `init_gems_rb` (`BUNDLE_NEW_GEMFILE_NAME`)
+* `init_gems_rb` (`BUNDLE_NEW_GEMFILE_NAME`):
    Generate a `gems.rb` instead of a `Gemfile` when running `bundle init`.
-* `prefer_gems_rb` (`BUNDLE_PREFER_GEMS_RB`)
+* `prefer_gems_rb` (`BUNDLE_PREFER_GEMS_RB`):
    Prefer `gems.rb` to `Gemfile` when Bundler is searching for a Gemfile.
 * `unlock_source_unlocks_spec` (`BUNDLE_UNLOCK_SOURCE_UNLOCKS_SPEC`):
    Whether running `bundle update --source NAME` unlocks a gem with the given
    name. Defaults to `true`.
-* `update_requires_all_flag` (`BUNDLE_UPDATE_REQUIRES_ALL_FLAG`)
+* `update_requires_all_flag` (`BUNDLE_UPDATE_REQUIRES_ALL_FLAG`):
    Require passing `--all` to `bundle update` when everything should be updated,
    and disallow passing no options to `bundle update`.
 * `allow_bundler_dependency_conflicts` (`BUNDLE_ALLOW_BUNDLER_DEPENDENCY_CONFLICTS`):
@@ -243,6 +243,9 @@ learn more about their operation in [bundle install(1)][bundle-install].
 * `skip_default_git_sources` (`BUNDLE_SKIP_DEFAULT_GIT_SOURCES`):
    Whether Bundler should skip adding default git source shortcuts to the
    Gemfile DSL.
+* `install_caches_by_default` (`BUNDLE_INSTALL_CACHES_BY_DEFAULT`):
+   Whether `bundle install` with no options passed should act as if `--cache`
+   has been passed.
 * `suppress_install_using_messages` (`BUNDLE_SUPPRESS_INSTALL_USING_MESSAGES`):
    Avoid printing `Using ...` messages during installation when the version of
    a gem has not changed.
diff --git a/man/bundle-install.ronn b/man/bundle-install.ronn
index d4bc34909a..8b880176f0 100644
--- a/man/bundle-install.ronn
+++ b/man/bundle-install.ronn
@@ -12,7 +12,7 @@ bundle-install(1) -- Install the dependencies specified in your Gemfile
                  [--deployment]
                  [--force]
                  [--frozen]
-                 [--no-cache]
+                 [--cache]
                  [--no-prune]
                  [--path PATH]
                  [--system]
@@ -98,10 +98,10 @@ time `bundle install` is run, use `bundle config` (see bundle-config(1)).
   Installs the gems specified in the bundle to the system's Rubygems location.
   This overrides any previous configuration of `--path`.
 
-* `--no-cache`:
-  Do not update the cache in `vendor/cache` with the newly bundled gems. This
+* `--cache`:
+  Update the cache in `vendor/cache` with the newly bundled gems. This
   does not remove any gems in the cache but keeps the newly bundled gems from
-  being cached during the install.
+  being cached during the install. Defaults to true.
 
 * `--no-prune`:
   Don't remove stale gems from the cache when the installation finishes.
diff --git a/spec/commands/package_spec.rb b/spec/commands/package_spec.rb
index 9b0de7f4e4..e254bca2ce 100644
--- a/spec/commands/package_spec.rb
+++ b/spec/commands/package_spec.rb
@@ -301,5 +301,33 @@ RSpec.describe "bundle install with gem sources" do
       bundle "install --no-cache"
       expect(bundled_app("vendor/cache").children).to be_empty
     end
+
+    context "when install_caches_by_default is set to false" do
+      before { bundle! "config install_caches_by_default false" }
+
+      it "does not update the cache if --cache is not passed" do
+        create_file "gems.rb", <<-G
+          source "file://#{gem_repo1}"
+          gem "rack"
+        G
+        bundled_app("vendor/cache").mkpath
+        expect(bundled_app("vendor/cache").children).to be_empty
+
+        bundle! "install"
+        expect(bundled_app("vendor/cache").children).to be_empty
+      end
+
+      it "updates the cache if --cache is passed" do
+        create_file "gems.rb", <<-G
+          source "file://#{gem_repo1}"
+          gem "rack"
+        G
+        bundled_app("vendor/cache").mkpath
+        expect(bundled_app("vendor/cache").children).to be_empty
+
+        bundle! "install --cache"
+        expect(bundled_app("vendor/cache").children).not_to be_empty
+      end
+    end
   end
 end