前言
emqtt插件开发网络上可参考的地方很少，这里做一个记录，希望能帮你节约一点时间。
引用
-emqtt
-emq-plugin-template插件模板
-参考的emqtt-kafka插件
环境
-编译环境 erlang OTP19
-运行环境 64位Centos7
-emqtt-2.3.7
编译
添加引用
#修改emq-relx的Makefile
DEPS += emqttd emq_modules emq_dashboard emq_retainer emq_recon emq_reloader \
emq_auth_clientid emq_auth_username emq_auth_ldap emq_auth_http \
emq_auth_mysql emq_auth_pgsql emq_auth_redis emq_auth_mongo \
emq_sn emq_coap emq_stomp emq_plugin_template emq_web_hook \
emq_lua_hook emq_auth_jwt <font color=#ff0000> emqttd_plugin_kafka_bridge </font>
#添加插件git路径，或者用svn、cp（本地路径)
dep_emqttd_plugin_kafka_bridge = git https://github.com/msdevanms/emqttd_plugin_kafka_bridge master
添加插件自启动
#在emq-relx/data/loaded_plugins文件末尾添加
emqttd_plugin_kafka_bridge.
添加配置
#修改emq-relx的relx.config，只列出添加项
{release, {emqttd, "2.3.7"}, [
...
#添加
kafkamocker,
ekaf,
ranch,
{emqttd_plugin_kafka_bridge, load},
#添加结束
{emq_plugin_template, load}
]}.
{overlay, [
#添加配置文件
{copy, "rel/conf/plugins/plugin.config", "etc/plugins/emqttd_plugin_kafka_bridge.config"},
#添加结束
]}.
运行
$ cd _rel/emqttd/bin
$ ./emqttd start
kafka桥接修改的示例代码如下
%%%-----------------------------------------------------------------------------
%%% Copyright (c) 2016 Huang Rui<vowstar@gmail.com>, All Rights Reserved.
%%%
%%% Permission is hereby granted, free of charge, to any person obtaining a copy
%%% of this software and associated documentation files (the "Software"), to deal
%%% in the Software without restriction, including without limitation the rights
%%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%%% copies of the Software, and to permit persons to whom the Software is
%%% furnished to do so, subject to the following conditions:
%%%
%%% The above copyright notice and this permission notice shall be included in all
%%% copies or substantial portions of the Software.
%%%
%%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
%%% SOFTWARE.
%%%-----------------------------------------------------------------------------
%%% @doc
%%% emqttd_plugin_kafka_bridge.
%%%
%%% @end
%%%-----------------------------------------------------------------------------
-module(emqttd_plugin_kafka_bridge).
-include("../../emqttd/include/emqttd.hrl").
-include("../../emqttd/include/emqttd_protocol.hrl").
-include("../../emqttd/include/emqttd_internal.hrl").
-export([load/1, unload/0]).
%% Hooks functions
-export([on_client_connected/3, on_client_disconnected/3]).
-export([on_client_subscribe/4, on_client_unsubscribe/4]).
-export([on_message_publish/2, on_message_delivered/4, on_message_acked/4]).
-record(struct, {lst=[]}).
%% Called when the plugin application start
load(Env) ->
ekaf_init([Env]),
emqttd:hook('client.connected', fun ?MODULE:on_client_connected/3, [Env]),
emqttd:hook('client.disconnected', fun ?MODULE:on_client_disconnected/3, [Env]),
emqttd:hook('client.subscribe', fun ?MODULE:on_client_subscribe/4, [Env]),
emqttd:hook('client.unsubscribe', fun ?MODULE:on_client_unsubscribe/4, [Env]),
emqttd:hook('message.publish', fun ?MODULE:on_message_publish/2, [Env]),
emqttd:hook('message.delivered', fun ?MODULE:on_message_delivered/4, [Env]),
emqttd:hook('message.acked', fun ?MODULE:on_message_acked/4, [Env]).
%%-----------client connect start-----------------------------------%%
on_client_connected(ConnAck, Client = #mqtt_client{client_id = ClientId}, _Env) ->
io:format("client ~s connected, connack: ~w~n", [ClientId, ConnAck]),
Json = mochijson2:encode([
{type, <<"connected">>},
{client_id, ClientId},
{cluster_node, node()}
% ,{ts, emqttd_time:now_to_secs()}
]),
ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json)),
{ok, Client}.
%%-----------client connect end-------------------------------------%%
%%-----------client disconnect start---------------------------------%%
on_client_disconnected(Reason, _Client = #mqtt_client{client_id = ClientId}, _Env) ->
% io:format("client ~s disconnected, reason: ~w~n", [ClientId, Reason]),
Json = mochijson2:encode([
{type, <<"disconnected">>},
{client_id, ClientId},
{reason, Reason},
{cluster_node, node()}
% ,{ts, emqttd_time:now_to_secs()}
]),
ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json)),
ok.
%%-----------client disconnect end-----------------------------------%%
%%-----------client subscribed start---------------------------------------%%
%% should retain TopicTable
on_client_subscribe(ClientId,Username, TopicTable, _Env) ->
io:format("client ~s will subscribe ~p~n", [ClientId, TopicTable]),
case TopicTable of
[_|_] ->
%% If TopicTable list is not empty
Key = proplists:get_keys(TopicTable),
%% build json to send using ClientId
Json = mochijson2:encode([
{type, <<"subscribed">>},
{client_id, ClientId},
{topic, lists:last(Key)},
{cluster_node, node()}
]),
ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json));
_ ->
%% If TopicTable is empty
io:format("empty topic ~n")
end,
{ok, TopicTable}.
%on_client_subscribe_after(ClientId, TopicTable, _Env) ->
% io:format("client ~s subscribed ~p~n", [ClientId, TopicTable]),
% case TopicTable of
% [_|_] ->
% %% If TopicTable list is not empty
% Key = proplists:get_keys(TopicTable),
% %% build json to send using ClientId
% Json = mochijson2:encode([
% {type, <<"subscribed">>},
% {client_id, ClientId},
% {topic, lists:last(Key)},
% {cluster_node, node()}
% ,{ts, emqttd_time:now_to_secs()}
% ]),
% ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json));
% _ ->
% %% If TopicTable is empty
% io:format("empty topic ~n")
% end,
% {ok, TopicTable}.
%%-----------client subscribed end----------------------------------------%%
%%-----------client unsubscribed start----------------------------------------%%
on_client_unsubscribe(ClientId,Username, Topics, _Env) ->
io:format("client ~s unsubscribe ~p~n", [ClientId, Topics]),
% build json to send using ClientId
Json = mochijson2:encode([
{type, <<"unsubscribed">>},
{client_id, ClientId},
{topic, lists:last(Topics)},
{cluster_node, node()}
% ,{ts, emqttd_time:now_to_secs()}
]),
ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json)),
{ok, Topics}.
%%-----------client unsubscribed end----------------------------------------%%
%%-----------message publish start--------------------------------------%%
%% transform message and return
on_message_publish(Message = #mqtt_message{topic = <<"$SYS/", _/binary>>}, _Env) ->
{ok, Message};
on_message_publish(Message, _Env) ->
io:format("publish ~s~n", [emqttd_message:format(Message)]),
% From = Message#mqtt_message.from,
% Sender = Message#mqtt_message.sender,
Topic = Message#mqtt_message.topic,
Payload = Message#mqtt_message.payload,
QoS = Message#mqtt_message.qos,
Timestamp = Message#mqtt_message.timestamp,
Json = mochijson2:encode([
{type, <<"published">>},
% {client_id, From},
{topic, Topic},
% 如果是二进制 {payload, binary_to_list(Payload)},
{payload, Payload},
{qos, QoS},
{cluster_node, node()}
% ,{ts, emqttd_time:now_to_secs(Timestamp)}
]),
ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json)),
{ok, Message}.
%%-----------message delivered start--------------------------------------%%
on_message_delivered(ClientId, Username, Message, _Env) ->
io:format("delivered to client ~s: ~s~n", [ClientId, emqttd_message:format(Message)]),
% From = Message#mqtt_message.from,
% Sender = Message#mqtt_message.sender,
Topic = Message#mqtt_message.topic,
Payload = Message#mqtt_message.payload,
QoS = Message#mqtt_message.qos,
Timestamp = Message#mqtt_message.timestamp,
Json = mochijson2:encode([
{type, <<"delivered">>},
{client_id, ClientId},
% {from, From},
{topic, Topic},
% 如果是二进制 {payload, binary_to_list(Payload)},
{payload, Payload},
{qos, QoS},
{cluster_node, node()}
% ,{ts, emqttd_time:now_to_secs(Timestamp)}
]),
ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json)),
{ok, Message}.
%%-----------message delivered end----------------------------------------%%
%%-----------acknowledgement publish start----------------------------%%
on_message_acked(ClientId, Username, Message, _Env) ->
io:format("client ~s acked: ~s~n", [ClientId, emqttd_message:format(Message)]),
% From = Message#mqtt_message.from,
% Sender = Message#mqtt_message.sender,
Topic = Message#mqtt_message.topic,
Payload = Message#mqtt_message.payload,
QoS = Message#mqtt_message.qos,
Timestamp = Message#mqtt_message.timestamp,
Json = mochijson2:encode([
{type, <<"acked">>},
{client_id, ClientId},
% {from, From},
{topic, Topic},
% 如果是二进制 {payload, binary_to_list(Payload)},
{payload, Payload},
{qos, QoS},
{cluster_node, node()}
% ,{ts, emqttd_time:now_to_secs(Timestamp)}
]),
ekaf:produce_sync(<<"broker_message">>, list_to_binary(Json)),
{ok, Message}.
%% ===================================================================
%% ekaf_init
%% ===================================================================
ekaf_init(_Env) ->
%% Get parameters
{ok, Kafka} = application:get_env(emqttd_plugin_kafka_bridge, kafka),
BootstrapBroker = proplists:get_value(bootstrap_broker, Kafka),
PartitionStrategy= proplists:get_value(partition_strategy, Kafka),
%% Set partition strategy, like application:set_env(ekaf, ekaf_partition_strategy, strict_round_robin),
application:set_env(ekaf, ekaf_partition_strategy, PartitionStrategy),
%% Set broker url and port, like application:set_env(ekaf, ekaf_bootstrap_broker, {"127.0.0.1", 9092}),
application:set_env(ekaf, ekaf_bootstrap_broker, BootstrapBroker),
%% Set topic
application:set_env(ekaf, ekaf_bootstrap_topics, <<"broker_message">>),
{ok, _} = application:ensure_all_started(kafkamocker),
{ok, _} = application:ensure_all_started(gproc),
{ok, _} = application:ensure_all_started(ranch),
{ok, _} = application:ensure_all_started(ekaf),
io:format("Init ekaf with ~p~n", [BootstrapBroker]).
%% Called when the plugin application stop
unload() ->
emqttd:unhook('client.connected', fun ?MODULE:on_client_connected/3),
emqttd:unhook('client.disconnected', fun ?MODULE:on_client_disconnected/3),
emqttd:unhook('client.subscribe', fun ?MODULE:on_client_subscribe/3),
emqttd:unhook('client.subscribe.after', fun ?MODULE:on_client_subscribe_after/3),
emqttd:unhook('client.unsubscribe', fun ?MODULE:on_client_unsubscribe/3),
emqttd:unhook('message.publish', fun ?MODULE:on_message_publish/2),
emqttd:unhook('message.acked', fun ?MODULE:on_message_acked/3),
emqttd:unhook('message.delivered', fun ?MODULE:on_message_delivered/3).
