regression in consistent hashing plugin after #5077

[lazedo]

we work a lot with consistent hashing and noticed a regression in behaviour after #5077

when consistency is configured with a header and that header is not set on the published msg, a crash in rabbit_exchange_type_consistent_hash.erl , this is different from previous versions. if this is the new desired behaviour, how can we prevent clients from publishing without the header? can the msg be rejected ?

value_to_hash({header, Header}, Msg0) ->
    maps:get(Header, mc:routing_headers(Msg0, [x_headers]));

should be changed to below to restore behaviour

value_to_hash({header, Header}, Msg0) ->
    maps:get(Header, mc:routing_headers(Msg0, [x_headers]), undefined);

[lukebakken]

Hello, would you please provide the full stack trace you see with this crash?

[hugh-zen]

The same issue is happening to me and i've reproduced it easily by creating a consistent hashing exchange with: hash-header = hash_id

Then publish a message without the header set.

2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> Connection (<0.27400.0>) closing: internal error in channel (<0.27408.0>): {{badkey,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> <<"hash_id">>},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{erlang,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> map_get,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [<<"hash_id">>,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> #{}],
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{error_info,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> #{module =>
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> erl_erts_errors}}]},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {rabbit_exchange_type_consistent_hash,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> value_to_hash,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 2,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{file,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> "rabbit_exchange_type_consistent_hash.erl"},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {line,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 265}]},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {rabbit_exchange_type_consistent_hash,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> route,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 3,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{file,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> "rabbit_exchange_type_consistent_hash.erl"},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {line,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 71}]},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {rabbit_exchange,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> route1,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 4,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{file,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> "rabbit_exchange.erl"},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {line,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 389}]},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {rabbit_exchange,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> route,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 3,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{file,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> "rabbit_exchange.erl"},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {line,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 369}]},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {rabbit_channel,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> handle_method,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 3,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{file,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> "rabbit_channel.erl"},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {line,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 1281}]},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {rabbit_channel,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> handle_cast,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 2,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{file,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> "rabbit_channel.erl"},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {line,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 659}]},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {gen_server2,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> handle_msg,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 2,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> [{file,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> "gen_server2.erl"},
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> {line,
2024-07-23 13:42:13.476706+00:00 [warning] <0.27400.0> 1056}]}]}
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> supervisor: {<0.27406.0>,amqp_channel_sup}
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> errorContext: shutdown
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> reason: reached_max_restart_intensity
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> offender: [{pid,<0.27408.0>},
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> {id,channel},
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> {mfargs,{amqp_channel,start_link,
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> [direct,<0.27400.0>,1,<0.27407.0>,
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> {<<"rabbit@003f76197cf0.1721731945.27400.0">>,
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> 1}]}},
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> {restart_type,transient},
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> {significant,true},
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> {shutdown,300000},
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0> {child_type,worker}]
2024-07-23 13:42:13.477116+00:00 [error] <0.27406.0>
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> supervisor: {<0.27410.0>,rabbit_channel_sup}
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> errorContext: child_terminated
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> reason: {{badkey,<<"hash_id">>},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{erlang,map_get,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [<<"hash_id">>,#{}],
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{error_info,#{module => erl_erts_errors}}]},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {rabbit_exchange_type_consistent_hash,value_to_hash,2,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{file,"rabbit_exchange_type_consistent_hash.erl"},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {line,265}]},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {rabbit_exchange_type_consistent_hash,route,3,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{file,"rabbit_exchange_type_consistent_hash.erl"},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {line,71}]},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {rabbit_exchange,route1,4,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{file,"rabbit_exchange.erl"},{line,389}]},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {rabbit_exchange,route,3,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{file,"rabbit_exchange.erl"},{line,369}]},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {rabbit_channel,handle_method,3,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{file,"rabbit_channel.erl"},{line,1281}]},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {rabbit_channel,handle_cast,2,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{file,"rabbit_channel.erl"},{line,659}]},
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> {gen_server2,handle_msg,2,
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> [{file,"gen_server2.erl"},{line,1056}]}]}
2024-07-23 13:42:13.476551+00:00 [error] <0.27410.0> offender: [{pid,<0.27412.0>},

[michaelklishin]

This is just a rarely used way of using the plugin. Please put together an executable way to reproduce (as a public repo on GitHub).

[jeremy-smith-maco]

I have also encountered this issue. I have created a reproduction case using a simple python script taken from the consistent hashing example. You can see the original line on 28 I replaced with an empty headers object on line 30. https://gist.github.com/jeremy-smith-maco/1dc7eeee7ae189678e98de93fdbebf8f

[ansd]

Fixed in #11808