wrap network errors to inst-fs in service exception

closes FOO-1467
flag=none

TEST PLAN:
  1) disable inst-fs
  2) network errors should get
    reported as service errors because
    we already have error paths for those.

Change-Id: Ib8cd10d05156b809e78602d24a6a6d92f10465ab
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/256728
Reviewed-by: Simon Williams <simon@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
QA-Review: Ethan Vizitei <evizitei@instructure.com>
Product-Review: Ethan Vizitei <evizitei@instructure.com>

lib/inst_fs.rb

@@ -165,7 +165,11 @@ module InstFS
       data = {}
       data[file_name] = file_object
 
-      response = CanvasHttp.post(url, form_data: data, multipart: true, streaming: true)
+      begin
+        response = CanvasHttp.post(url, form_data: data, multipart: true, streaming: true)
+      rescue Net::ReadTimeout, CanvasHttp::CircuitBreakerError
+        raise InstFS::ServiceError, "unable to communicate with instfs"
+      end
       if response.class == Net::HTTPCreated
         json_response = JSON.parse(response.body)
         return json_response["instfs_uuid"] if json_response.key?("instfs_uuid")

spec/lib/inst_fs_spec.rb

@@ -545,6 +545,14 @@ describe InstFS do
           file_object: File.open("public/images/a.png")
         )
       end
+
+      it "wraps network errors in a service exception" do
+        instfs_uuid = "1234-abcd"
+        allow(CanvasHttp).to receive(:post).and_raise(Net::ReadTimeout)
+        expect do
+          InstFS.direct_upload(file_name: "a.png", file_object: File.open("public/images/a.png"))
+        end.to raise_error(InstFS::ServiceError)
+      end
     end
 
     context "duplicate" do