Move the circuitbreaker check out in a separate processbvl-circuitbreaker-process

Moving the check out of the general requests, makes sure we don't have
any slowdown in the regular requests.

To keep the process performing this checks small, the check is still
performed inside a unicorn. But that is called from a process running
on the same server.

Because the checks are now done outside normal request, we can have a
simpler failure strategy:

The check is now performed in the background every
`circuitbreaker_check_interval`. Failures are logged in redis. The
failures are reset when the check succeeds. Per check we will try
`circuitbreaker_access_retries` times within
`circuitbreaker_storage_timeout` seconds.

When the number of failures exceeds
`circuitbreaker_failure_count_threshold`, we will block access to the
storage.

After `failure_reset_time` of no checks, we will clear the stored
failures. This could happen when the process that performs the checks
is not running.

1 files changed, 2 insertions, 13 deletions

diff --git a/spec/models/application_setting_spec.rb b/spec/models/application_setting_spec.rb
index 0b7e16cc33c..ef480e7a80a 100644
--- a/spec/models/application_setting_spec.rb
+++ b/spec/models/application_setting_spec.rb
@@ -115,9 +115,8 @@ describe ApplicationSetting do
     end
 
     context 'circuitbreaker settings' do
-      [:circuitbreaker_backoff_threshold,
-       :circuitbreaker_failure_count_threshold,
-       :circuitbreaker_failure_wait_time,
+      [:circuitbreaker_failure_count_threshold,
+       :circuitbreaker_check_interval,
        :circuitbreaker_failure_reset_time,
        :circuitbreaker_storage_timeout].each do |field|
         it "Validates #{field} as number" do
@@ -126,16 +125,6 @@ describe ApplicationSetting do
                            .is_greater_than_or_equal_to(0)
         end
       end
-
-      it 'requires the `backoff_threshold` to be lower than the `failure_count_threshold`' do
-        setting.circuitbreaker_failure_count_threshold = 10
-        setting.circuitbreaker_backoff_threshold = 15
-        failure_message = "The circuitbreaker backoff threshold should be lower "\
-                          "than the failure count threshold"
-
-        expect(setting).not_to be_valid
-        expect(setting.errors[:circuitbreaker_backoff_threshold]).to include(failure_message)
-      end
     end
 
     context 'repository storages' do