Erlang in the Heroku
Cloud
XXX
What do we do?
Software Engineers
Heroku Routing Team
What is Heroku?
Cloud Application
PaaS
We manage servers so you don't
have to.
Keeps your apps running.
Painless deploys
Simple, instant scaling.
Getting Started in the
Cloud
Launch EC2 Instance
Install OS packages
Configure & Secure
Clone your app
Add monitoring
When you grow, repeat.
Getting Started in the
Cloud
Launch EC2 Instance
Install OS packages
Configure & Secure
Clone your app
Add monitoring
When you grow, repeat.
The Heroku Way
Provision an app
$ heroku create -s cedar
Creating cold-river-2049... done, stack is cedar
http://cold-river-2049.herokuapp.com/ | [email protected]:cold-river-2049.git
Git remote heroku added
Instant Deployment
$ git push heroku master
-----> Heroku receiving push
-----> ...
-----> Launching... done, v5
http://myapp.herokuapp.com deployed to Heroku
Instant Scaling
$ heroku scale web+30 worker=7
Scaling web processes... done, now running 31
Scaling worker processes... done, now running 7
HTTP Routing Mesh
Balances requests between
"dynos"
Intelligent fail-over
Written in Erlang!
Supported Languages
Ruby, Node.js, Python, Java,
Scala, Clojure
And...
Supported Languages
Anything. Including Erlang.
Language support
comes
from "buildpacks"
more on Buildpacks
later...
More about Erlang!
Buildpacks for R14B03, R15B
My First Heroku
Erlang Deploy
Git init...
$ mkdir ef_example
$ cd ef_example
$ git init
Initialized empty Git repository in /Users/path/ef_example/.git/
Rebar ALL THE
BOILERPLATE
$ rebar create-app appid=ef
==> ef_example (create-app)
Writing src/ef.erl
Writing src/ef.app.src
Writing src/ef_app.erl
Writing src/ef_sup.erl
Writing include/ef_log.hrl
Writing rebar.config
Writing .gitignore
$ rebar compile
==> ef_example (compile)
Compiled src/ef_app.erl
Compiled src/ef.erl
Compiled src/ef_sup.erl
Make sure it works
locally
$ erl -pa-pa ebin -s-s ef_app
Erlang R15B01Erlang R15B01 (erts-5.9.1) [source] [64-bit-bit] [smp:4:4]
Eshell V5.9.1 (abort with ^G)
1> application:which_applicationsapplication:which_applications().
[{ef,[],"1"},
{stdlib,"ERTS CXC 138 10","1.18.1"},
{kernel,"ERTS CXC 138 10","2.15.1"}]
2>
User switch commandcommand
--> q
Commit
$ git commit -m "rebar create-app"
[master (root-commit) 3836e22] rebar create-app
7 files changed, 171 insertions(+), 0 deletions(-)
create mode 100644 .gitignore
create mode 100644 include/ef_log.hrl
create mode 100644 rebar.config
create mode 100644 src/ef.app.src
create mode 100644 src/ef.erl
create mode 100644 src/ef_app.erl
create mode 100644 src/ef_sup.erl
Install the Heroku
client
Use the rubygem or Heroku toolbelt:
gem install heroku
# OR
open https://toolbelt.heroku.com
Create the heroku
app
$ heroku help create
Usage: heroku apps:create [NAME]
create a new app
--addons ADDONS # a comma-delimited list of addons to install
-b, --buildpack BUILDPACK # a buildpack url to use for this app
-r, --remote REMOTE # the git remote to create, default "heroku"
-s, --stack STACK # the stack on which to create the app
$ heroku create erlang-factory-2012-example \
--stack cedar --buildpack \
https://github.com/archaelus/heroku-buildpack-erlang.git
Creating erlang-factory-2012-example... done, stack is cedar
http://erlang-factory-2012-example.herokuapp.com/ | [email protected]:erlang-factory-2012-example.git
Git remote heroku added
Deploy your
application
Launch EC2 Instance
Install erlang
Clone your app
Build it
Write some init scripts
Debug your init scripts. For ever.
Trolololololol
Launch EC2 Instance
Install erlang
Clone your app
Build it
Write some init scripts
Debug your init scripts. For ever.
J/K
$ git push heroku master
Counting objects: 11, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (9/9), done.
Writing objects: 100% (11/11), 1.99 KiB, done.
Total 11 (delta 1), reused 0 (delta 0)
-----> Heroku receiving push
-----> Fetching custom buildpack... done
-----> Erlang app detected
-----> Using Erlang/OTP r15b
-------> Fetching Erlang/OTP r15b
-------> Unpacking Erlang/OTP r15b
-------> Installing Erlang/OTP r15b
-----> Installing Rebar from buildpack
-----> Building with Rebar
==> build_32vbusz5o9hkq (get-deps)
==> build_32vbusz5o9hkq (compile)
Compiled src/ef.erl
Compiled src/ef_app.erl
Compiled src/ef_sup.erl
-----> Discovering process types
Procfile declares types -> (none)
-----> Compiled slug size is 53.3MB
-----> Launching... done, v4
http://erlang-factory-2012-example.herokuapp.com deployed to Heroku
$ heroku ps:scale web=1
$ heroku open
Opening http://erlang-factory-2012-example.herokuapp.com/
$ heroku logs
2012-03-28T03:30:26+00:00 heroku[api]: Config add BUILDPACK_URL by [email protected]
2012-03-28T03:30:26+00:00 heroku[api]: Release v2 created by [email protected]
2012-03-28T03:31:06+00:00 heroku[slugc]: Slug compilation started
2012-03-28T03:31:20+00:00 heroku[slugc]: Slug compilation failed: error fetching custom buildpack
2012-03-28T03:33:01+00:00 heroku[slugc]: Slug compilation started
2012-03-28T03:33:40+00:00 heroku[api]: Config add PATH by [email protected]
2012-03-28T03:33:40+00:00 heroku[api]: Release v3 created by [email protected]
2012-03-28T03:33:41+00:00 heroku[api]: Release v4 created by [email protected]
2012-03-28T03:33:41+00:00 heroku[api]: Deploy 3836e22 by [email protected]
2012-03-28T03:33:41+00:00 heroku[web.1]: State changed from created to down
2012-03-28T03:33:42+00:00 heroku[slugc]: Slug compilation finished
2012-03-28T03:35:15+00:00 heroku[router]: Error H14 (No web processes running) -> GET erlang-factory-2012-example.herokuapp.com/ dyno= queue= wait= service= status=503 bytes=
2012-03-28T03:35:16+00:00 heroku[router]: Error H14 (No web processes running) -> GET erlang-factory-2012-example.herokuapp.com/ dyno= queue= wait= service= status=503 bytes=
2012-03-28T03:35:16+00:00 heroku[router]: Error H14 (No web processes running) -> GET erlang-factory-2012-example.herokuapp.com/favicon.ico dyno= queue= wait= service= status=503 bytes=
2012-03-28T03:35:16+00:00 heroku[router]: Error H14 (No web processes running) -> GET erlang-factory-2012-example.herokuapp.com/favicon.ico dyno= queue= wait= service= status=503 bytes=
Let's add a web
server
$ cat rebar.config
{erl_opts, [debug_info]}.
{deps, [ {cowboy, "", {git,
"git://github.com/extend/cowboy.git", {branch, "master"}}
}]}.
%
Add cowboy to our app.src
$ rebar get-deps compile
...
Make sure it still
works
$ erl -pa-pa ebin -env-env ERL_LIBS deps \
-s-s ef_app -ef-ef http_port 16526
Erlang R15B01Erlang R15B01 (erts-5.9.1) [source] [64-bit-bit] [smp:4:4]
Eshell V5.9.1 (abort with ^G)
1> application:which_applicationsapplication:which_applications().
[{ef,[],"1"},
{cowboy,"Small, fast, modular HTTP server.","0.5.0"},
{stdlib,"ERTS CXC 138 10","1.18.1"},
{kernel,"ERTS CXC 138 10","2.15.1"}]
2> application:get_envapplication:get_env(ef, http_port).
{ok,16526}
3> ef_app:configef_app:config(http_port).
16526
Add a basic http handler
-module-module(ef_http_handler).
-behaviour-behaviour(cowboy_http_handler).
-export-export([init/3, handle/2, terminate/2]).
initinit({_Any, http}, Req, []) ->
{ok, Req, undefined}.
handlehandle(Req, State) ->
{ok, R2} = cowboy_http_req:replycowboy_http_req:reply(
200, [{'Content-Type', "text/plain"}],
<<"Hello world!">>, Req),
{ok, R2, State}.
terminateterminate(_Req, _State) -> ok.
Configure cowboy in ef_app
start_phasestart_phase(listen, _Type, _Args) ->
Dispatch = [{'_', [
{'_', ef_http_handler,
]}
],
cowboy:start_listenercowboy:start_listener(
http, 100, cowboy_tcp_transport,
[{port, configconfig(http_port)}],
cowboy_http_protocol,
[{dispatch, Dispatch}]
),
ok.
Add start phases to app.src
,{start_phases,
[{listen, []}
]}
Check it all works
$ erl -pa ebin -env ERL_LIBS deps \
-s ef_app -ef http_port 16526
Erlang R15B01 (erts-5.9.1) ...
...
$ curl localhost:16526
Hello world!
Adding a Procfile
$ cat Procfile
web: erl -pa ebin -env ERL_LIBS deps -s ef_app -ef http_port $PORT \
-noshell -noinput
Tedious deployment
git push heroku master
Enjoy frozen margarita
heroku open ; heroku
logs -t
Profit.
tl;dr
1. Take an Erlang web server
2. Add a Procfile (simplified init
script)
3. heroku create --arguments
4. git push heroku master
github.com/archaelus/erlang-factory-2012-example
What else can I do??
Add-ons!
Installing an addon
$ heroku addons:add redistogo
----> Adding redistogo to warm-ice-9184... done, v13 (free)
$ heroku config
...
REDISTOGO_URL => redis://redistogo:[email protected]:9887/
...
So you said something
about Buildpacks...
Buildpacks
What is a Buildpack?
A buildpack is responsible for
language
and framework-specific details.
What is a Buildpack?
Installs language binaries
Resolves dependencies
Builds / compiles your code
The Erlang Buildpack
(condensed version)
The Erlang Buildpack
1. Fetch language binaries:
#!/bin/sh
# usage: bin/compile <build-dir> <cache-dir>
...
(
cd ${cache}
echo "-------> Fetching Erlang/OTP $version"
curl -sO https://s3.amazonaws.com/heroku-buildpack-erlang
/${version}.tgz
)
Erlang Buildpack (cont.)
2. Unpack + install OTP
#!/bin/sh
...
echo "-------> Unpacking Erlang/OTP $version"
...
tar jxf ${cache}/${version}.tgz -C ${ERLROOT} --strip-components
echo "-------> Installing Erlang/OTP $version"
ln -s ${ERLROOT} /app/otp
${ERLROOT}/Install -minimal /app/otp
...
Erlang Buildpack (cont.)
3. Install Rebar & get-deps
#!/bin/sh
...
PATH=/app/otp/bin:$PATH
cd $build
ifif [ ! -e "rebar" ]; thenthen
echo "-----> Installing Rebar from buildpack"
cp ${buildpack_dir}/opt/rebar ./
fifi
echo "-----> Building with Rebar"
unsetunset GIT_DIR
(./rebar get-deps compile 2>&1 |
sed -u 's/^/ /') || exitexit 1
Awesome! What can't I
do??
Limitations
HTTP-only routing
No direct inter-process
communication
Single TCP port available to bind
So what's it good for?
"Traditional" HTTP server apps
Batch processing that pulls off a
queue
Anything that uses an
intermediary for communication
The Future
(no promises)
The Future
Multi-protocol routing
Bind to multiple/many ports
Dyno-dyno networking
Run any Erlang app you like
We're Hiring!
We're Hiring!
We're, er, dining.
Drop by the office for
lunch/coffee/drinks sometime
We're (Er)Lounging
We're trying to get into the
habit of regular Erlounges with
talks and workshops.
Stay tuned on meetup.com
The End.
