Simplify /-/liveness check to avoid connecting to the database

The previous implementation would hit the database each time
and provide a dummy response. If the database goes down, this
means all application workers would be taken out of service.
Simplify this check by using a Rails middleware that intercepts
this endpoint and returns a 200 response.

1 files changed, 57 insertions, 0 deletions

diff --git a/spec/lib/gitlab/middleware/liveness_health_check_spec.rb b/spec/lib/gitlab/middleware/liveness_health_check_spec.rb
new file mode 100644
index 00000000000..3dee13b7770
--- /dev/null
+++ b/spec/lib/gitlab/middleware/liveness_health_check_spec.rb
@@ -0,0 +1,57 @@
+require 'spec_helper'
+
+describe Gitlab::Middleware::LivenessHealthCheck do
+  let(:app) { double(:app) }
+  let(:middleware) { described_class.new(app) }
+  let(:env) { {} }
+
+  describe '#call' do
+    context 'outside IP' do
+      before do
+        env['REMOTE_ADDR'] = '8.8.8.8'
+      end
+
+      it 'returns a 404' do
+        env['PATH_INFO'] = described_class::LIVENESS_PATH
+
+        response = middleware.call(env)
+
+        expect(response[0]).to eq(404)
+      end
+
+      it 'forwards the call for other paths' do
+        env['PATH_INFO'] = '/'
+
+        expect(app).to receive(:call)
+
+        middleware.call(env)
+      end
+    end
+
+    context 'whitelisted IP' do
+      before do
+        env['REMOTE_ADDR'] = '127.0.0.1'
+      end
+
+      it 'returns 200 response when endpoint is hit' do
+        env['PATH_INFO'] = described_class::LIVENESS_PATH
+
+        expect(app).not_to receive(:call)
+
+        response = middleware.call(env)
+
+        expect(response[0]).to eq(200)
+        expect(response[1]).to eq({ 'Content-Type' => 'text/plain' })
+        expect(response[2]).to eq(['GitLab is alive'])
+      end
+
+      it 'forwards the call for other paths' do
+        env['PATH_INFO'] = '/-/readiness'
+
+        expect(app).to receive(:call)
+
+        middleware.call(env)
+      end
+    end
+  end
+end