From b819708599d31276b49869f46c06f202ec584eca Mon Sep 17 00:00:00 2001
From: Emily S <emily.stolfo@elastic.co>
Date: Tue, 14 Apr 2020 14:37:47 +0200
Subject: [PATCH] Ensure that the running agent's config is used when restarted
 (#763)

* Ensure that the running agent's config is used when restarted

* Add changelog entry
---
 CHANGELOG.asciidoc       | 1 +
 lib/elastic_apm.rb       | 2 +-
 spec/elastic_apm_spec.rb | 9 +++++++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.asciidoc b/CHANGELOG.asciidoc
index 5662e8b60..7540526c7 100644
--- a/CHANGELOG.asciidoc
+++ b/CHANGELOG.asciidoc
@@ -50,6 +50,7 @@ endif::[]
 
 - Ensure that the log level is updated for the config's logger when value is changed {pull}755[#755]
 - Set config `false` values to `false`, not `nil` {pull}761[#761]
+- Ensure that the previously running agent's config is used in `ElasticAPM.restart` {pull}763[#763]
 
 [float]
 ===== Added
diff --git a/lib/elastic_apm.rb b/lib/elastic_apm.rb
index c0ed0aa38..87a7494b9 100644
--- a/lib/elastic_apm.rb
+++ b/lib/elastic_apm.rb
@@ -51,7 +51,7 @@ def stop
     # one, if it is provided.
     # Starts the agent if it is not running.
     # Stops and starts the agent if it is running.
-    def restart(config = {})
+    def restart(config = nil)
       config ||= agent&.config
       stop if running?
       start(config)
diff --git a/spec/elastic_apm_spec.rb b/spec/elastic_apm_spec.rb
index f85f9972a..9b9b86bd2 100644
--- a/spec/elastic_apm_spec.rb
+++ b/spec/elastic_apm_spec.rb
@@ -36,12 +36,21 @@
       end
     end
     context 'when a new config is passed' do
+      before { ElasticAPM.start }
       it 'restarts the agent with the new config' do
         ElasticAPM.restart(api_buffer_size: 10)
         expect(ElasticAPM::Agent).to be_running
         expect(ElasticAPM.agent.config.api_buffer_size).to be(10)
       end
     end
+    context 'when no new config is passed' do
+      before { ElasticAPM.start(api_buffer_size: 10) }
+      it 'restarts the agent with the same config' do
+        ElasticAPM.restart
+        expect(ElasticAPM::Agent).to be_running
+        expect(ElasticAPM.agent.config.api_buffer_size).to be(10)
+      end
+    end
   end
 
   context 'when running', :mock_intake do