Introduce _bulk_docs max_doc_count limit

Let users specify the maximum document count for the _bulk_docs requests. If
the document count exceeds the maximum it would return a 413 HTTP error. This
would also signal the replicator to try to bisect the _bulk_docs array into
smaller batches.

4 files changed, 32 insertions, 1 deletions

diff --git a/rel/overlay/etc/default.ini b/rel/overlay/etc/default.ini
index 3630259a1..43e1c0ba3 100644
--- a/rel/overlay/etc/default.ini
+++ b/rel/overlay/etc/default.ini
@@ -55,6 +55,10 @@ changes_doc_ids_optimization_threshold = 100
 ; for size calculation instead of 7.
 max_document_size = 8000000 ; bytes
 ;
+; Maximum number of documents in a _bulk_docs request. Anything larger
+; returns a 413 error for the whole request
+;max_bulk_docs_count = 10000
+;
 ; Maximum attachment size.
 ; max_attachment_size = infinity
 ;
diff --git a/src/chttpd/src/chttpd.erl b/src/chttpd/src/chttpd.erl
index 699601c0e..e8639ed8d 100644
--- a/src/chttpd/src/chttpd.erl
+++ b/src/chttpd/src/chttpd.erl
@@ -956,6 +956,8 @@ error_info(request_entity_too_large) ->
     {413, <<"too_large">>, <<"the request entity is too large">>};
 error_info({request_entity_too_large, {attachment, AttName}}) ->
     {413, <<"attachment_too_large">>, AttName};
+error_info({request_entity_too_large, {bulk_docs, Max}}) when is_integer(Max) ->
+    {413, <<"max_bulk_docs_count_exceeded">>, integer_to_binary(Max)};
 error_info({request_entity_too_large, DocID}) ->
     {413, <<"document_too_large">>, DocID};
 error_info({error, security_migration_updates_disabled}) ->
diff --git a/src/chttpd/src/chttpd_db.erl b/src/chttpd/src/chttpd_db.erl
index 5cfbd1d5f..5af98fe3a 100644
--- a/src/chttpd/src/chttpd_db.erl
+++ b/src/chttpd/src/chttpd_db.erl
@@ -484,6 +484,11 @@ db_req(#httpd{method='POST',path_parts=[_,<<"_bulk_docs">>]}=Req, Db) ->
     DocsArray0 ->
         DocsArray0
     end,
+    MaxDocs = config:get_integer("couchdb", "max_bulk_docs_count", 10000),
+    case length(DocsArray) =< MaxDocs of
+        true -> ok;
+        false -> throw({request_entity_too_large, {bulk_docs, MaxDocs}})
+    end,
     couch_stats:update_histogram([couchdb, httpd, bulk_docs], length(DocsArray)),
     Options = case chttpd:header_value(Req, "X-Couch-Full-Commit") of
     "true" ->
diff --git a/src/chttpd/test/eunit/chttpd_db_doc_size_tests.erl b/src/chttpd/test/eunit/chttpd_db_doc_size_tests.erl
index 88e2797a3..2b04050a2 100644
--- a/src/chttpd/test/eunit/chttpd_db_doc_size_tests.erl
+++ b/src/chttpd/test/eunit/chttpd_db_doc_size_tests.erl
@@ -29,6 +29,7 @@ setup() ->
     Hashed = couch_passwords:hash_admin_password(?PASS),
     ok = config:set("admins", ?USER, ?b2l(Hashed), _Persist=false),
     ok = config:set("couchdb", "max_document_size", "50"),
+    ok = config:set("couchdb", "max_bulk_docs_count", "2"),
     TmpDb = ?tempdb(),
     Addr = config:get("chttpd", "bind_address", "127.0.0.1"),
     Port = mochiweb_socket_server:get(chttpd, port),
@@ -39,7 +40,8 @@ setup() ->
 teardown(Url) ->
     delete_db(Url),
     ok = config:delete("admins", ?USER, _Persist=false),
-    ok = config:delete("couchdb", "max_document_size").
+    ok = config:delete("couchdb", "max_document_size"),
+    ok = config:delete("couchdb", "max_bulk_docs_count").
 
 create_db(Url) ->
     {ok, Status, _, _} = test_request:put(Url, [?CONTENT_JSON, ?AUTH], "{}"),
@@ -67,6 +69,7 @@ all_test_() ->
                     fun post_single_doc/1,
                     fun put_single_doc/1,
                     fun bulk_doc/1,
+                    fun bulk_docs_too_many_docs/1,
                     fun put_post_doc_attach_inline/1,
                     fun put_multi_part_related/1,
                     fun post_multi_part_form/1
@@ -100,6 +103,23 @@ bulk_doc(Url) ->
     Expect = {[{<<"error">>,<<"document_too_large">>},{<<"reason">>,<<>>}]},
     ?_assertEqual(Expect, ResultJson).
 
+
+bulk_docs_too_many_docs(Url) ->
+    Docs = "{\"docs\": ["
+        "{\"doc1\": \"{}\"}, "
+        "{\"doc2\": \"{}\"}, "
+        "{\"doc3\": \"{}\"}"
+    "]}",
+    {ok, Code, _, ResultBody} = test_request:post(Url ++ "/_bulk_docs/",
+        [?CONTENT_JSON, ?AUTH], Docs),
+    ResultJson = ?JSON_DECODE(ResultBody),
+    ExpectJson = {[
+        {<<"error">>,<<"max_bulk_docs_count_exceeded">>},
+        {<<"reason">>,<<"2">>}
+    ]},
+    ?_assertEqual({413, ExpectJson}, {Code, ResultJson}).
+
+
 put_post_doc_attach_inline(Url) ->
     Body1 = "{\"body\":\"This is a body.\",",
     Body2 = lists:concat(["{\"body\":\"This is a body it should fail",