Erlang HTTP问题

时间：2016-10-19 19:22:03

标签： http erlang cowboy

根本无法向Erlang / Cowboy提出请求。我可以从erlang shell中创建一个，但在运行牛仔版本时却不能。尝试使用'hackney'库：

hackney:start(),

{ok, _, _, Ref} = hackney:request(
  get, <<"http://www.youtube.com">>, [], <<>>, [{pool, default}]
),
{ok, Body} = hackney:body(Ref),
io:format("body: ~p~n~n", [Body]),

错误：

Error in process <0.361.0> on node 'cta_erlang_backend@127.0.0.1' with exit value:
{[{reason,undef},
  {mfa,{hello_handler,handle,2}},
  {stacktrace,[{hackney,start,[],[]},
               {hello_handler,handle,2,
                              [{file,"src/hello_handler.erl"},{line,18}]},
               {cowboy_handler,handler_handle,4,
                               [{file,"src/cowboy_handler.erl"},{line,111}]},
               {cowboy_protocol,execute,4,
                                [{file,"src/cowboy_protocol.erl"},
                                 {line,442}]}]},
  {req,[{socket,#Port<0.267>},
        {transport,ranch_tcp},
        {connection,keepalive},
        {pid,<0.361.0>},
        {method,<<"POST">>},
        {version,'HTTP/1.1'},
        {peer,{{10,0,0,1},40049}},
        {host,<<"10.0.0.103">>},
        {host_info,undefined},
        {port,8080},
        {path,<<"/">>},
        {path_info,undefined},
        {qs,<<>>},
        {qs_vals,undefined},
        {bindings,[]},
        {headers,[{<<"host">>,<<"10.0.0.103:8080">>},
                  {<<"connection">>,<<"keep-alive">>},
                  {<<"content-length">>,<<"4">>},
                  {<<"cache-control">>,<<"no-cache">>},
                  {<<"origin">>,
                   <<"chrome-extension://fdmmgilgnpjigdojojpjoooidkmcomcm">>},
                  {<<"user-agent">>,
                   <<"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/39.0.2171.65 Chrome/39.0.2171.65 Safari/537.36">>},
                  {<<"content-type">>,<<"text/plain;charset=UTF-8">>},
                  {<<"accept">>,<<"*/*">>},
                  {<<"accept-encoding">>,<<"gzip, deflate">>},
                  {<<"accept-language">>,<<"en-GB,en-US;q=0.8,en;q=0.6">>}]},
        {p_headers,[{<<"connection">>,[<<"keep-alive">>]}]},
        {cookies,undefined},
        {meta,[]},
        {body_state,waiting},
        {buffer,<<"asdf">>},
        {multipart,undefined},
        {resp_compress,false},
        {resp_state,waiting},
        {resp_headers,[]},
        {resp_body,<<>>},
        {onresponse,undefined}]},
  {state,{state}}],
 [{cowboy_protocol,execute,4,[{file,"src/cowboy_protocol.erl"},{line,442}]}]}

=ERROR REPORT==== 19-Oct-2016::18:56:51 ===
Ranch listener my_http_listener had connection process started with cowboy_protocol:start_link/4 at <0.361.0> exit with reason:


{[{reason,undef},{mfa,{hello_handler,handle,2}},{stacktrace,[{hackney,start,[],[]},{hello_handler,handle,2,[{file,"src/hello_handler.erl"},{line,18}]},{cowboy_handler,handler_handle,4,[{file,"src/cowboy_handler.erl"},{line,111}]},{cowboy_protocol,execute,4,[{file,"src/cowboy_protocol.erl"},{line,442}]}]},{req,[{socket,#Port<0.267>},{transport,ranch_tcp},{connection,keepalive},{pid,<0.361.0>},{method,<<"POST">>},{version,'HTTP/1.1'},{peer,{{10,0,0,1},40049}},{host,<<"10.0.0.103">>},{host_info,undefined},{port,8080},{path,<<"/">>},{path_info,undefined},

{QS，＆LT;＆LT;＆GT;＆GT;}，{qs_vals，未定义}，{绑定，[]}，{标头，[{＆LT;＆LT; “宿主” ＆GT;＆GT;，＆LT;＆LT; “10.0.0.103:8080">>},{<<"connection">>,<<"keep-alive">>},{<<"content-length “＆GT;＆GT;，＆LT;＆LT;” 4 “＆GT;＆GT;}，{＆LT;＆LT;” 缓存控制 “＆GT;＆GT;，＆LT;＆LT;” 无缓存“＆GT;＆GT;}，{ ＆LT;＆LT; “原点” ＆GT;＆GT;，＆LT;＆LT; “铬扩展：// fdmmgilgnpjigdojojpjoooidkmcomcm” ＆GT;＆GT;}，{＆LT;＆LT; “用户代理” ＆GT;＆GT;，＆LT;＆LT; “Mozilla / 5.0（X11; Linux x86_64）AppleWebKit / 537.36（KHTML，与Gecko一样）Ubuntu Chromium / 39.0.2171.65 Chrome / 39.0.2171.65 Safari / 537.36”＆gt;＆gt;}，{＆lt;＆lt;＆lt;“content-type” ＆GT;＆GT;，＆LT;＆LT; “text / plain的;字符集= UTF-8” ＆GT;＆GT;}，{＆LT;＆LT; “接受” ＆GT;＆GT;，＆LT;＆LT;“ / “＆gt;＆gt;}，{＆lt;＆lt;”accept-encoding“＆gt;＆gt;，＆lt;＆lt;”gzip，deflate“＆gt;＆gt;}，{＆lt;＆lt;”accept-language“＆gt ;＆GT;，＆LT;＆LT; “EN-GB，EN-US; q = 0.8，连接; q = 0.6” ＆GT;＆GT;}]}，{p_headers，[{＆LT;＆LT; “连接” ＆GT;＆GT ;，并[d＆LT; “保持活动” ＆GT;＆GT;]}]}，{饼干，未定义}，{元，[]}，{body_state，等待}，{buffe R，＆LT;＆LT; “ASDF” ＆GT;＆GT;}，{多，未定义}，{resp_compress，FALSE}，{resp_state，等待}，{resp_headers，[]}，{resp_body，＆LT;＆LT;＆GT;＆GT ;}，{onresponse，未定义}]}，{状态，{状态}}]，[{cowboy_protocol，执行，如图4所示，[{文件， “SRC / cowboy_protocol.erl”}，{线，442}]}]}

hello_handler.erl：

-module(hello_handler).
-behaviour(cowboy_http_handler).

-export([init/3]).
-export([handle/2]).
-export([terminate/3]).

-record(state, {
}).

init(_, Req, _Opts) ->
    hackney:start(),
    {ok, Req, #state{}}.

handle(Req, State) ->
    {Method, Req2} = cowboy_req:method(Req),
    case Method of
        <<"POST">> ->
            {ok, _, _, Ref} = hackney:request(get, <<"http://www.youtube.com">>,
                [], <<>>, [{pool, default}]),
            {ok, Body} = hackney:body(Ref),
            io:format("body: ~p~n~n", [Body]),
            ResponseBody = <<"Hello Erl POST!">>;
        <<"GET">> ->
            ResponseBody = <<"Hello Erlang1!">>
    end,
    {ok, Req2} = cowboy_req:reply(200,
        [{<<"content-type">>, <<"text/plain">>}],
        ResponseBody,
        Req),
    {ok, Req2, State}.

terminate(_Reason, _Req, _State) ->
    ok.

1 个答案:

答案 0 :(得分：0)

{[{reason,undef},
  {mfa,{hello_handler,handle,2}},
    {stacktrace,[{hackney,start,[],[]},
           {hello_handler,handle,2,
                          [{file,"src/hello_handler.erl"},{line,18}]},
           {cowboy_handler,handler_handle,4,
                           [{file,"src/cowboy_handler.erl"},{line,111}]},
           {cowboy_protocol,execute,4,
                            [{file,"src/cowboy_protocol.erl"},
                             {line,442}]}]},

在cowboy_handler.erl 111行崩溃，https://github.com/ninenines/cowboy/blob/1.1.x/src/cowboy_handler.erl#L111

原因：hello_handler：handle / 2是undef

所以

  1. 确保src目录中的hello_handler.erl;

  2. 使用rebar compile;

    3. 进行编译

  3. 重启服务器或erlang shell中的l(hello_handler)

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