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Add SSL support for Yesod

Ok this is going to be quick one. I serve haskell-serbia website with nginx web server that sits in front and just passes all requests to haskell warp server. I wanted to serve it over https and first step was to get a ssl certificate.

There are free certificates available on letsencrypt .

Once you install the certificate for your domain you need to make few adjustments in your virtual host file.

Here is mine example:

-- /etc/nginx/sites-available/default

upstream yesod {
        keepalive 8;

server {
        listen 443 ssl;
        server_name haskell-serbia.com www.haskell-serbia.com;
        access_log /var/log/nginx/access_yesod.log;
        error_log /var/log/nginx/error_yesod.log;
        ssl_certificate /etc/letsencrypt/live/haskell-serbia.com-0001/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/haskell-serbia.com-0001/privkey.pem;
        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
        ssl_prefer_server_ciphers on;
        ssl_ciphers 'EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH';
        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 https://yesod/;
            proxy_redirect off;

        location /excluded {
            return 403;

In order to have ssl support in your Yesod app you need to look at Network.Wai.Handler.WarpTLS. There is a constructor function tlsSettings that returns, well, TLSSettings if you pass it the path for the certificate and key files you generated with letsencrypt.

-- add import
import Network.Wai.Handler.WarpTLS
-- ...
-- example TLSSettings generation
tlsS :: TLSSettings
tlsS = tlsSettings "/etc/letsencrypt/live/DOMAIN/fullchain.pem" "/etc/letsencrypt/live/DOMAIN/privkey.pem"

Your appMain function serves the app and you need to adjust it to use runTLS function instead of runSettings in the Application.hs file

-- Application.hs
appMain :: IO ()
appMain = do
    settings <- loadYamlSettingsArgs

    foundation <- makeFoundation settings
    app <- makeApplication foundation

    -- Run the application with Warp
    -- runSettings (warpSettings foundation) app
    runTLS tlsS  (warpSettings foundation)  app

And that's it. Reload your nginx server sudo service nginx restart and enjoy your safe surfing!

Tags: yesod ssl