亚马逊上的Haskell（Yesod）

Question

I want to deploy a system made in Yesod using Amazon Web Service. But can't find a good tutorial or steps on how to do it.

Looking for a web host that can handle Haskell says that Amazon EC2 is the best. But it doesn't tell how to do it or give a link. Also it has a comment that I can link my S3 to EC2.

Answer 1

I'd suggest you to look at https://github.com/snoyberg/keter/ and Halcyon at https://halcyon.sh/

They are deployment managers for Haskell web apps. Keter was written in Haskell and Halcyon shell.

In my opinion keter handles amazon better and halcyon is more for dependencies, initial setup, heroku and digital ocean. Both are awesome.

(UPDATE 25-02-2015)

Keter is mentioned at Developing Web Apps with Haskel and Yesod, 2nd Edition, launched this February 2015, ( http://www.yesodweb.com/book/deploying-your-webapp ). I highly recommend it, both the tools and the book.

Also, I'd recommend heroku if it's just a pet project or something to test on.

Links:

http://shop.oreilly.com/product/0636920035664.do

http://www.amazon.com/Developing-Apps-Haskell-Yesod-Safety-Driven/dp/1491915595/ref=dp_ob_title_bk

https://github.com/snoyberg/keter/

https://halcyon.sh/

Answer 2

I could use Nginx as a front end server, and use Yesod app as the reverse proxy on EC2/Ubuntu 14.04. I didn't try Keter, as Nginx/Yesod just works fine. I assume you already install the Nginx.

Installation of Haskell/Yesod

As the Yesod author comments in http://www.yesodweb.com/page/quickstart , Stackage ( https://www.stackage.org ) is really easy to install dependent libraries, and even Haskell itself. I followed this site ( https://github.com/commercialhaskell/stack/blob/master/doc/install_and_upgrade.md ) to easily install Stack on Ubuntu 14.04.

1. wget -q -O- https://s3.amazonaws.com/download.fpcomplete.com/ubuntu/fpco.key | sudo apt-key add -
2. echo 'deb http://download.fpcomplete.com/ubuntu/trusty stable main'|sudo tee /etc/apt/sources.list.d/fpco.list
3. sudo apt-get update && sudo apt-get install stack -y

You can use stack ghci to launch Haskell REPL.

Create and build Yesod project

• stack new my-project yesod-sqlite && cd my-project
• stack install yesod-bin cabal-install --install-ghc
• stack build

Use swap to benefit more memory

For my EC2 server, I havd only 1G memory not to finish the build, but I could use swap to use more memory - https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04

1. sudo fallocate -l 4G /swapfile
2. sudo chmod 600 /swapfile
3. sudo mkswap /swapfile
4. sudo swapon /swapfile

Development test

• stack exec -- yesod devel

You can launch webbrowser to check with http://localhost:3000 .

Deployment

From http://www.yesodweb.com/book/deploying-your-webapp , I need three components to deploy to other machine.

1. Your executable.
2. The config folder.
3. The static folder.

The stack build command gives me the location of the executable:

my-project-0.0.0: install
Installing library in
/home/a/my-project/.stack-work/install/x86_64-linux/lts-3.13/7.10.2/lib/x86_64-linux-ghc-7.10.2/my-project-0.0.0-Khn8lQEgR1HARzYGStlvPe
Installing executable(s) in
/home/a/my-project/.stack-work/install/x86_64-linux/lts-3.13/7.10.2/bin
Registering my-project-0.0.0...

The executable is located in /home/a/my-project/.stack-work/install/x86_64-linux/lts-3.13/7.10.2/bin . I could copy the files (executable, static, and config) in ~/deployment directory to check the Yesod works fine.

This is the directory structure.

├── config
│   ├── client_session_key.aes
...
│   └── test-settings.yml
├── my-project
└── static
    ...

Change port number

Change the port number in config/settings.yml

port:           "_env:PORT:3002"
approot:        "_env:APPROOT:http://localhost:3002"

(I'm not sure why) However, to make the settings.yml work, you need to copy the file in current directory, then run the ./my_project settings.yml .

Check http://localhost:3002 .

Setup Nginx server

This is the conf file for Yesod.

# the IP(s) on which your node server is running. I chose port 3000.
upstream yesod {
        server 127.0.0.1:3002;
        keepalive 8;
}

# the nginx server instance
server {
        listen 0.0.0.0:80;
        server_name yesod.example.com;
        access_log /var/log/nginx/access_yesod.log;
        error_log /var/log/nginx/error_yesod.log;

        location / {
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $http_host;
            proxy_set_header X-NginX-Proxy true;

            proxy_pass http://yesod/;
            proxy_redirect off;
        }

        location /excluded {
            return 403;
        } 
}

Copy this file in /etc/nginx/site-enabled (or make symlink from site-available), then relaunch the nginx sudo server nginx restart .

Now, you can access the Yesod app from http://yesod.example.com .

References

• https://hackage.haskell.org/package/stack
• Deploying Yesod web app
• Change Yesod port number
• Haskell cabal issue with Mac OS X 10.11? (cannot satisfy -package-id)

Answer 3

Yesod book has a whole chapter on how to deploy your Yesod app http://www.yesodweb.com/book/deploying-your-webapp

Amazon is recommended there, so it should work on amazon without any trouble. If you'll have more specific questions regarding keter -- please post them as new questions then.