SyntaxMore than

@phueslerPatrick Huesler

SyntaxMore than

a ruby dev’s POVerlang

web apis with

snowboarding

Surfing

WIPEOUT

erlang

so don’t believe everything I say

beginnerI’m an erlang

introductionerlang

this is not an

refreshererlang

functionallanguage

runtimesystem

OTPopen telecom platform

erlang?why

concurrentseriously

actorswith built in

distributedbecause it is

tolerantfault

hot swaping

shellremote

woogaerlang at

challengestechnical

for Diamond Dash20,543,500monthly active users

http://www.appdata.com/apps/facebook/127995567256931-diamond-dash (03/10/2012)

for Diamond Dash3,871,133daily active users

http://www.appdata.com/apps/facebook/127995567256931-diamond-dash (03/10/2012)

for Monster World6,500 RPS

backend traffic up to

Database?what does mean that for a

write heavyread/write ratio?

architecturesdifferent

is faster than no databasedatabase

no

stateful

all the wayS3

Let’s use

http://www.slideshare.net/wooga/from-0-to-1000000-daily-users-with-erlang

http://www.slideshare.net/wooga/from-0-to-1000000-daily-users-with-erlang

in erlangcheapprocesses are

Web APIserlang

rebar

$:rebar create-app appid=aloha

like rubygems does?dependencies

how to manage

rebar

$: rebar get-deps$: rebar compile$: rebar get-deps compile

1 % Compiler Options for rebar 2 {erl_opts, [ 3 {src_dirs, ["src", "test"]}, 4 debug_info 5 ]}. 6 7 % Dependencies 8 {deps, [ 9 {elli, ".*", {git, "git://github.com/knutin/elli.git", "HEAD"}}, 10 {etest, ".*", {git, "git://github.com/wooga/etest.git", "HEAD"}}, 11 {etest_http, ".*", {git, "git://github.com/wooga/etest_http.git", "HEAD"}} 12 ]}. 13 14 % Which files to cleanup when rebar clean is executed. 15 {clean_files, ["ebin/*.beam"]}.

shall we use?webserver

What

elli

1 elli:start_link([ 2 {callback, aloha_api}, 3 {port, 3000} 4 ])

Routing?how do I do

1 Path = [<<"foo">>, <<"bar">>], 2 HTTPMethod = "GET", 3 Request = {HTTPMethod, Path}, 4 RouteDefinitions = [{{"GET",[<<"foo">>,<<"bar">>]},

{my_handler, my_method, []}}], 5 case erl_route_url:match(Request, RouteDefinitions) of 6 {error, notfound} -> 7 io:format("path not found"); 8 {ok, Params, {M,F,_}} -> 9 apply(M,F,Params) 10 end.

wrong!!!you’re doing it

pattern matching

use

1 handle(Req, _Args) -> 2 Path = elli_request:path(Req), 3 handle(Req#req.method, Path, Req). 4 5 handle('GET',[<<"foo">>, <<"bar"], Req) -> 6 {ok, [], <<"kekahi mau pipi">>}; 7 8 handle(_, _, _Req) -> 9 {404, [], <<"wipe out!">>}.

middleware?does it support

1 Config = [ 2 {mods, [ 3 {aloha_ware, []}, 4 {mahalo_ware, []}, 5 ]} 6 ], 7 8 elli:start_link([ 9 {callback, aloha_api}, 10 {port, 3000}, 11 {callback_args, Config} 12 ]).

request_completerequest_throwrequest_exitrequest_errorrequest_parse_errorbad_requestclient_closedclient_timeoutelli_startup

events

1 handle_event(request_complete, [ 2 Req, 3 ResponseCode, 4 ResponseHeaders, 5 ResponseBody, 6 Timings 7 ], Config) -> 8 9 TimingKeys = [ 10 accepted, 11 request_start, 12 heades_end, 13 body_end, 14 user_start, 15 user_end, 16 request_end 17 ], 18 ok;

awesome monitoring

1 handle_event(request_throw, [ 2 Req, 3 Exception,Stack 4 ], _Config) -> 5 ok; 6 7 handle_event(request_exit, [ 8 Req, 9 Exit, 10 Stack 11 ], _Config) -> 12 ok; 13 14 handle_event(request_error, [ 15 Req, 16 Error, 17 Stack 18 ], _Config) -> 19 ok; 20

environments?how about

$: erl -pa deps/*/ebin ebin \n -config myconfig

1 [ 2 {aloha, [ 3 {worker_port, 3333} 4 ] 5 }, 6 7 {lager, [ 8 {handlers, [ 9 {lager_console_backend, debug}, 10 {lager_file_backend, [ 11 {"log/debug.log", debug, 10485760, "$D0", 5}, 12 {"log/error.log", error, 10485760, "$D0", 5}, 13 {"log/console.log", info, 10485760, "$D0", 5} 14 ]} 15 ]} 16 ]} 17 ].

Config file

logging?how about

1 error_logger:info_msg("aloha\n"). 2 % prints aloha\nok 3 4 error_logger:warning_msg("freak set"). 5 % prints freak set ahead \nok 6 7 error_logger:error_msg("wipe out\n"). 8 % prints wipe out\nok

sasl

=PROGRESS REPORT==== 8-Oct-2012::12:06:24 === supervisor: {local,sasl_safe_sup} started: [{pid,<0.39.0>}, {name,overload}, {mfargs,{overload,start_link,[]}}, {restart_type,permanent}, {shutdown,2000}, {child_type,worker}]

=PROGRESS REPORT==== 8-Oct-2012::12:06:24 === supervisor: {local,sasl_sup} started: [{pid,<0.37.0>}, {name,sasl_safe_sup}, {mfargs, {supervisor,start_link, [{local,sasl_safe_sup},sasl,safe]}}, {restart_type,permanent}, {shutdown,infinity}, {child_type,supervisor}]

=PROGRESS REPORT==== 8-Oct-2012::12:06:24 === supervisor: {local,sasl_sup} started: [{pid,<0.40.0>}, {name,release_handler}, {mfargs,{release_handler,start_link,[]}}, {restart_type,permanent}, {shutdown,2000}, {child_type,worker}]

unix style?how about

lager

1 [ 2 {aloha, [ 3 {worker_port, 3333} 4 ] 5 }, 6 7 {lager, [ 8 {handlers, [ 9 {lager_console_backend, debug}, 10 {lager_file_backend, [ 11 {"log/debug.log", debug, 10485760, "$D0", 5}, 12 {"log/error.log", error, 10485760, "$D0", 5}, 13 {"log/console.log", info, 10485760, "$D0", 5} 14 ]} 15 ]} 16 ]} 17 ].

Config file

1 start(_StartType, _StartArgs) -> 2 ok = application:start(compiler), 3 ok = application:start(syntax_tools), 4 ok = application:start(lager), 5 6 % start mochiweb module reloader 7 reloader:start(), 8 9 elli:start_link([{callback, aloha_api}, {port, 3000}]), 10 aloha_sup:start_link().

1 dev_start(App) -> dev_start(App, temporary). 2 3 dev_start(App, Type) -> 4 case application:start(App, Type) of 5 {error, {not_started, DepApp}} -> 6 dev_start(DepApp), 7 dev_start(App, Type); 8 ok -> ok; 9 {error, {already_started, App}} -> ok 10 end.

1 lager:debug("aloha\n"). 2 % prints aloha\nok 3 4 lager:warning("freak set"). 5 % prints freak set ahead \nok 6 7 lager:error("wipe out\n"). 8 % prints wipe out\nok

Unit testing?

how about

eunit

the easy waystacktrace

no

etest

1 -module(aloha_utils_test). 2 -compile(export_all). 3 4 % Include etest's assertion macros. 5 -include_lib("etest/include/etest.hrl"). 6 7 before_suite() -> 8 %start up applications 9 ok. 10 11 before_test() -> 12 %load fixtures 13 ok. 14 15 test_hello() -> 16 ?assert_equal("kekahi mau pipi", aloha_utils:hello()). 17 18 after_test() -> 19 % tear down fixtures 20 ok. 21 22 after_suite() -> 23 % stop applications 24 ok.

$: ./deps/etest/bin/etest-runner

http testing?

How about

1 -module (aloha_api_test). 2 -compile (export_all). 3 4 % etest macros 5 -include_lib ("etest/include/etest.hrl"). 6 % etest_http macros 7 -include_lib ("etest_http/include/etest_http.hrl"). 8 9 before_suite() -> 10 application:start(aloha). 11 12 before_test() -> ok. 13 14 after_test() -> ok. 15 16 after_suite() -> 17 application:stop(aloha). 18 19 test_aloha() -> 20 Response = ?perform_get("http://localhost:3000/aloha"), 21 ?assert_status(200, Response), 22 ?assert_body("kekahi mau pipi", Response).

$: ./deps/etest/bin/etest-runner

autoreload?

how about

Mochiwebreloader

1 start(_StartType, _StartArgs) -> 2 ok = application:start(compiler), 3 ok = application:start(syntax_tools), 4 ok = application:start(lager), 5 6 % start mochiweb module reloader 7 reloader:start(), 8 9 elli:start_link([{callback, aloha_api}, {port, 3000}]), 10 aloha_sup:start_link().

NIFsbeware of

auto compile?

how about

guard

1 # # -*- encoding : utf-8 -*- 2 3 guard 'shell' do 4 watch(%r{^src/.+\.erl$}) do |m| 5 puts `rebar compile` 6 end 7 end

deploying toheroku?

how ab bout

$: heroku create aloha-erl -s cedar

Heroku buildpack

$: heroku config:add BUILDPACK_URL=http://github.com/heroku/heroku-buildpack-erlang.git

procfile

web: erl -pa deps/*/ebin ebin-noshell-noinput-config priv/config/environments/development-s aloha_app

1 start(_StartType, _StartArgs) -> 2 ok = application:start(compiler), 3 ok = application:start(syntax_tools), 4 ok = application:start(lager), 5 reloader:start(), 6 7 {ok, DefaultPort} = application:get_env(aloha, worker_port), 8 Port = get_port(DefaultPort), 9 10 elli:start_link([{callback, aloha_api}, {port, Port}]), 11 aloha_sup:start_link(). 12 13 get_port(Default) -> 14 Key = "PORT", 15 case os:getenv(Key) of 16 false -> Default; 17 Val -> list_to_integer(Val) 18 end.

foreman

$: foreman start

deploy

$: git push heroku master

-----> Heroku receiving push-----> Fetching custom git buildpack... done-----> Erlang app detected-----> Installing Rebar from buildpack-----> Building with Rebar ==> build_1us6u0b7p5agc (get-deps) Pulling etest from {git,"git://github.com/wooga/etest.git","HEAD"}

...... Compiled src/aloha_api.erl-----> Discovering process types Procfile declares types -> web-----> Compiled slug size: 6.3MB-----> Launching... done, v19 http://aloha-erl.herokuapp.com deployed to Heroku

To git@heroku.com:aloha-erl.git 4bf3f39..198ba04 master -> master

$:curl aloha-erl.herokuapp.com/aloha

aloha-erl.herokuapp.com

mahalothat’s it folks

• https://twitter.com/wooga• https://twitter.com/knutin• https://twitter.com/hukl• https://twitter.com/hungryblank• https://twitter.com/guillermoo•https://twitter.com/klickmich• Andreas hasselberg• Johannes Huning

thanks to

• https://github.com/phuesler/aloha_erl • http://vimeo.com/45212367• https://github.com/knutin/elli• https://github.com/wooga/etest• https://github.com/wooga/etest_http• https://github.com/basho/lager• https://github.com/mochi/mochiweb/blob/master/src/reloader.erl• https://github.com/heroku/heroku-buildpack-erlang

Resources

• Erlang: The Movie - YouTube• bomb: http://www.flickr.com/photos/7969902@N07/511234695/

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