How do you use Gun as a Cowboy client?
I followed the Getting Started instructions for Cowboy, and I\'ve got Cowboy running and listening on port 8080, and I got the Hello Erlang! response when I ent
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A summary of the issues/suggestions from the comments discussion
For running your Erlang app (in this case including gun as a dependency), you need to have the path to beam and .app files discoverable to the shell. When using erlang.mk, the easiest way to do that would be running the release using
make runOn Cowboy side, to have Websocket handled correctly, you need to have a handler defined in your cowboy routes. See example in Cowboy Websocket example
See also Gun user guide for more details about handling Websocket in Gun
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Success!
~/erlang_programs/my_gun/src/my.erl:
-module(my). -compile(export_all). get() -> ... ws() -> {ok, _} = application:ensure_all_started(gun), {ok, ConnPid} = gun:open("localhost", 8080), {ok, _Protocol} = gun:await_up(ConnPid), gun:ws_upgrade(ConnPid, "/websocket"), receive {gun_ws_upgrade, ConnPid, ok, Headers} -> upgrade_success(ConnPid, Headers); {gun_response, ConnPid, _, _, Status, Headers} -> exit({ws_upgrade_failed, Status, Headers}); {gun_error, _ConnPid, _StreamRef, Reason} -> exit({ws_upgrade_failed, Reason}) %% More clauses here as needed. after 1000 -> exit(timeout) end, upgrade_success(ConnPid, Headers) -> io:format("Upgraded ~w. Success!~nHeaders:~n~p~n", [ConnPid, Headers]), gun:ws_send(ConnPid, {text, "It's raining!"}), receive {gun_ws, ConnPid, {text, Msg} } -> io:format("~s~n", [Msg]) end.On the cowboy side:
-module(myws_handler). -compile(export_all). init(Req, State) -> {cowboy_websocket, Req, State}. %Perform websocket setup websocket_handle({text, Msg}, State) -> { reply, {text, io_lib:format("Server received: ~s", [Msg]) }, State }; websocket_handle(_Other, State) -> %Ignore {ok, State}.Here's the output:
~/erlang_programs/my_gun$ gmake run gmake[1]: Entering directory '/Users/7stud/erlang_programs/my_gun/deps/gun' gmake[2]: Entering directory '/Users/7stud/erlang_programs/my_gun/deps/cowlib' gmake[2]: Leaving directory '/Users/7stud/erlang_programs/my_gun/deps/cowlib' gmake[2]: Entering directory '/Users/7stud/erlang_programs/my_gun/deps/ranch' gmake[2]: Leaving directory '/Users/7stud/erlang_programs/my_gun/deps/ranch' GEN rebar.config gmake[1]: Leaving directory '/Users/7stud/erlang_programs/my_gun/deps/gun' DEPEND my_gun.d ERLC my.erl APP my_gun ===> Starting relx build process ... ===> Resolving OTP Applications from directories: /Users/7stud/erlang_programs/my_gun/ebin /Users/7stud/erlang_programs/my_gun/deps /Users/7stud/.evm/erlang_versions/otp_src_19.2/lib/erlang/lib /Users/7stud/erlang_programs/my_gun/apps /Users/7stud/erlang_programs/my_gun/_rel ===> Resolved my_gun_release-1 ===> rendering builtin_hook_status hook to "/Users/7stud/erlang_programs/my_gun/_rel/my_gun_release/bin/hooks/builtin/status" ===> Including Erts from /Users/7stud/.evm/erlang_versions/otp_src_19.2/lib/erlang ===> release successfully created! ===> tarball /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release/my_gun_release-1.tar.gz successfully created! Exec: /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release/erts-8.2/bin/erlexec -boot /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release/releases/1/my_gun_release -mode embedded -boot_var ERTS_LIB_DIR /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release/lib -config /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release/releases/1/sys.config -args_file /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release/releases/1/vm.args -pa -- console Root: /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release /Users/7stud/erlang_programs/my_gun/_rel/my_gun_release heart_beat_kill_pid = 38883 Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false] =PROGRESS REPORT==== 10-Jul-2017::18:04:38 === supervisor: {local,sasl_safe_sup} started: [{pid,<0.353.0>}, {id,alarm_handler}, {mfargs,{alarm_handler,start_link,[]}}, {restart_type,permanent}, {shutdown,2000}, {child_type,worker}] =PROGRESS REPORT==== 10-Jul-2017::18:04:38 === supervisor: {local,sasl_sup} started: [{pid,<0.352.0>}, {id,sasl_safe_sup}, {mfargs, {supervisor,start_link, [{local,sasl_safe_sup},sasl,safe]}}, {restart_type,permanent}, {shutdown,infinity}, {child_type,supervisor}] =PROGRESS REPORT==== 10-Jul-2017::18:04:38 === supervisor: {local,sasl_sup} started: [{pid,<0.354.0>}, {id,release_handler}, {mfargs,{release_handler,start_link,[]}}, {restart_type,permanent}, {shutdown,2000}, {child_type,worker}] =PROGRESS REPORT==== 10-Jul-2017::18:04:38 === application: sasl started_at: 'my_gun@127.0.0.1' =PROGRESS REPORT==== 10-Jul-2017::18:04:38 === supervisor: {local,runtime_tools_sup} started: [{pid,<0.360.0>}, {id,ttb_autostart}, {mfargs,{ttb_autostart,start_link,[]}}, {restart_type,temporary}, {shutdown,3000}, {child_type,worker}] =PROGRESS REPORT==== 10-Jul-2017::18:04:38 === application: runtime_tools started_at: 'my_gun@127.0.0.1' Eshell V8.2 (abort with ^G) (my_gun@127.0.0.1)1> my:ws(). =PROGRESS REPORT==== 10-Jul-2017::18:04:41 === supervisor: {local,inet_gethost_native_sup} started: [{pid,<0.367.0>},{mfa,{inet_gethost_native,init,[[]]}}] =PROGRESS REPORT==== 10-Jul-2017::18:04:41 === supervisor: {local,kernel_safe_sup} started: [{pid,<0.366.0>}, {id,inet_gethost_native_sup}, {mfargs,{inet_gethost_native,start_link,[]}}, {restart_type,temporary}, {shutdown,1000}, {child_type,worker}] Upgraded <0.365.0>. Success! Headers: [{<<"connection">>,<<"Upgrade">>}, {<<"date">>,<<"Tue, 11 Jul 2017 00:04:40 GMT">>}, {<<"sec-websocket-accept">>,<<"pYv8QeeJfzQgaS/x8flZHyrIexk=">>}, {<<"server">>,<<"Cowboy">>}, {<<"upgrade">>,<<"websocket">>}] Server received: It's raining! ok (my_gun@127.0.0.1)2>讨论(0)
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