feat: add option to overwrite Docker read and open timeout values

docker/lib/dependabot/docker/update_checker.rb

@@ -300,17 +300,30 @@ def docker_repo_name
         "library/#{dependency.name}"
       end
 
+      # Defaults from https://github.com/deitch/docker_registry2/blob/bfde04144f0b7fd63c156a1aca83efe19ee78ffd/lib/registry/registry.rb#L26-L27
+      DEFAULT_DOCKER_OPEN_TIMEOUT_IN_SECONDS = 2
+      DEFAULT_DOCKER_READ_TIMEOUT_IN_SECONDS = 5
+
       def docker_registry_client
         @docker_registry_client ||=
           DockerRegistry2::Registry.new(
             "https://#{registry_hostname}",
             user: registry_credentials&.fetch("username", nil),
             password: registry_credentials&.fetch("password", nil),
-            read_timeout: 10,
+            read_timeout: docker_read_timeout_in_seconds,
+            open_timeout: docker_open_timeout_in_seconds,
             http_options: { proxy: ENV.fetch("HTTPS_PROXY", nil) }
           )
       end
 
+      def docker_open_timeout_in_seconds
+        ENV.fetch("DEPENDABOT_DOCKER_OPEN_TIMEOUT_IN_SECONDS", DEFAULT_DOCKER_OPEN_TIMEOUT_IN_SECONDS).to_i
+      end
+
+      def docker_read_timeout_in_seconds
+        ENV.fetch("DEPENDABOT_DOCKER_READ_TIMEOUT_IN_SECONDS", DEFAULT_DOCKER_READ_TIMEOUT_IN_SECONDS).to_i
+      end
+
       def sort_tags(candidate_tags, version_tag)
         candidate_tags.sort do |tag_a, tag_b|
           if comparable_version_from(tag_a) > comparable_version_from(tag_b)

docker/spec/dependabot/docker/update_checker_spec.rb

@@ -1433,6 +1433,40 @@ def stub_tag_with_no_digest(tag)
     end
   end
 
+  describe ".docker_read_timeout_in_seconds" do
+    context "when DEPENDABOT_DOCKER_READ_TIMEOUT_IN_SECONDS is set" do
+      it "returns the provided value" do
+        override_value = 10
+        stub_const("ENV", ENV.to_hash.merge("DEPENDABOT_DOCKER_READ_TIMEOUT_IN_SECONDS" => override_value))
+        expect(checker.send(:docker_read_timeout_in_seconds)).to eq(override_value)
+      end
+    end
+
+    context "when ENV does not provide an override" do
+      it "falls back to a default value" do
+        expect(checker.send(:docker_read_timeout_in_seconds))
+          .to eq(Dependabot::Docker::UpdateChecker::DEFAULT_DOCKER_READ_TIMEOUT_IN_SECONDS)
+      end
+    end
+  end
+
+  describe ".docker_open_timeout_in_seconds" do
+    context "when DEPENDABOT_DOCKER_OPEN_TIMEOUT_IN_SECONDS is set" do
+      it "returns the provided value" do
+        override_value = 10
+        stub_const("ENV", ENV.to_hash.merge("DEPENDABOT_DOCKER_OPEN_TIMEOUT_IN_SECONDS" => override_value))
+        expect(checker.send(:docker_open_timeout_in_seconds)).to eq(override_value)
+      end
+    end
+
+    context "when ENV does not provide an override" do
+      it "falls back to a default value" do
+        expect(checker.send(:docker_open_timeout_in_seconds))
+          .to eq(Dependabot::Docker::UpdateChecker::DEFAULT_DOCKER_OPEN_TIMEOUT_IN_SECONDS)
+      end
+    end
+  end
+
   private
 
   def stub_same_sha_for(*tags)