OSS licensing

There are so many different license models out there in the open-source community. I don’t know what all the fuss is about… I hate legal stuff, just ship it and ask for permissions later!

Nevertheless I have a license for my open source projects on github as well and it’s just there to say FU to everyone that actually cares about licensing. It’s called THE BEER-WARE LICENSE:

/*
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 */

THE (extended) BEER-WARE LICENSE

I modified it a little to come closer to my own needs (markdown + more beers!):

## License
"THE (extended) BEER-WARE LICENSE" (Revision 42.0815): [phoet](mailto:ps@nofail.de) contributed to this project.

As long as you retain this notice you can do whatever you want with this stuff.
If we meet some day, and you think this stuff is worth it, you can buy me some beers in return.

Cheers!

Bringing Usergroups on Ruby

I am one of the organizers of the local Ruby Usergroup in Hamburg for over two years now. We meet on a regular basis, every second wednesday each month. Some times we meet in a bar to grab some beers, some times we have full fledged community events with sponsors and high quality talks.

All this is currently managed using the On Ruby plattform that was created to bring the events close to

the Ruby devs. It also eases the process of creating events, submitting talks, finding locations and publishing all that to Twitter, Google+ and Mailinglists.

Some month ago, the project was forked by Cologne.rb and they built their custom version for the Ruby Usergroup in Cologne. After that some more Usergroups wanted to use the tool and that was the reason we merged the Cologne.rb codebase and created a whitelabel version of the application, which is customizable in many regards. It also comes with a Mobile version for iPhone and Android.

If you are interested in joining Hamburg, Cologne, Bremen, Saarland and Karlsruhe just follow the guide for creating your own OnRuby Usergroup!

Heroku Cedar Background Jobs for free!

I’m using Heroku mostly for playing around with latest technology and hosting free apps. Since Heroku changed their pricing model due to the introduction of the new process model some of my apps changed from free to paid, especially those that had some background jobs or nightly crons (I really did not get, why this happend).

Full Stack Background Processes

If you want to run a resque worker and a clockwork process within your web-app, this becomes a costly thing, even if those are just running some minor jobs in the night, because you need to pay for 2 additional dynos.
You could achieve this through defining multiple processes in your Procfile:

# Procfile
web: bundle exec rails server thin -p $PORT
worker: QUEUE=* bundle exec rake environment resque:work
clock: bundle exec clockwork app/clock.rb
heroku scale worker=1 clock=1

Sharing Addon Connections

As Heroku officially announced in their latest newsletter, it’s possible to share connections between multiple apps. In my case, this would be a connection to a redis key-value store, that is provided by Redistogo. It’s as simple as copying the environment configuration for the addon over to the second app:

heroku config | grep DATABASE_URL  --app sushi
=> DATABASE_URL   => postgres://lswlm...

heroku config:add DATABASE_URL=postgres://lswlm... --app sushi-analytics
=> Adding config vars: DATABASE_URL => postgres://lswlm...m/ldfoiusfsf
=> Restarting app... done, v74.

Going Freemium

So the solution for getting back to a free worker setup is combining 3 Heroku apps and a shared Redis connection through Redistogo:

heroku apps:create freemium-web --stack cedar --remote heroku
git push heroku master

heroku apps:create freemium-worker --stack cedar --remote worker
git push worker master

heroku apps:create freemium-clock --stack cedar --remote clock
git push clock master

heroku scale web=1 --app=freemium-web
heroku scale web=0 worker=1 --app=freemium-worker
heroku scale web=0 clock=1 --app=freemium-clock

heroku addons:add redistogo:nano --app=freemium-web

heroku config:add `heroku config -s --app=freemium-web|grep redis` --app=freemium-worker
heroku config:add `heroku config -s --app=freemium-web|grep redis` --app=freemium-clock

I created an example project running a Rails 3 application with a mounted Resque web, a Resque worker and a clock process with Clockwork.

Even simpler

If you are just looking for a simple solution of running a background process have a look at crony, a bootstrap project using rufus-scheduler.

Migrating an existing App to Heroku Celadon Cedar Stack

It’s currently not possible to do an automated migration from or to the Heroku Celadon Cedar Stack which started in May. The only help that you get from Heroku is this:

Migrating From Bamboo to Cedar

Before migrating to Bamboo, you should make sure your app runs on Ruby 1.9.2. If your app is not already deployed successfully to bamboo-mri-1.9.2, you should do that first, and then come back and try Cedar.

Once you’re sure your app is fully compatible with Ruby 1.9.2, create an app on the Cedar stack and push to it. Currently, stack:migrate does not work for moving apps to Cedar.

Since there seem to be no blogposts of how to do all the stuff with an existing application I will try to cover everything that I did to do the migration manually in this article.

Cedar is different

If you are looking at the new stack you will notice that a lot has changed with Cedar. Most of the Heroku CLI has changed to reflect the new possibilites that come with the Cedar stack. Since Cedar introduces a new way of handling processes on Heroku, most of the commands are now streamlined with this:

# old
heroku console
heroku rake db:migrate
# new 
heroku run console
heroku run rake db:migrate

# have a look at running processes
heroku ps

# look at logs of different processes and tail the output
heroku logs --ps web -t

Preparing the Migration

I started by cloning my current app from Heroku into another directory and creating a new Cedar app on Heroku:

git clone git@heroku.com:hamburg-on-ruby.git legacy
cd legacy
heroku create --stack cedar

Adapting Cedar changes

The docs for creating a Rails 3 app on Cedar reflect some of the changes that have been introduced with Cedar.

One of those is that PostgreSQL is now recommended for local development and you need to have the pg-gem in your Gemfile. Otherwise you will get errors while running rake commands:

heroku run rake db:migrate

  Running rake db:migrate attached to terminal... up, run.1
  (in /app)
  rake aborted!
  no such file to load -- pg

Since I developed my app with SQLite3 and I don’t want to learn, install and manage ANOTHER Database I split up the database stuff for development, test and production:

# Gemfile
group :production do
  gem "pg"
end

group :development, :test do
  gem "sqlite3-ruby", :require => "sqlite3"
end

and exclude production dependencies from my local environment:

# put this into your .profile
alias bd="bundle --without=production"

It’s also recommended to serve Rails through thin webserver and manage the application with the Procfile manager foreman:

# Gemfile
gem "foreman"
gem "thin"
# Procfile
web: bundle exec rails server thin -p $PORT
foreman start

After going through those chages you should be able to see your application on localhost:

open http://localhost:5000

The migration process

If the application is running on your development machine you can start the core migration process by putting your legacy application into maintenance mode, so that no database changes will be made:

heroku maintenance:on
# stop worker, crons or whatever might be changing the db

Database Migration

After you completely halted everything on your dyno, you can start dumping the database to your development machine (I thought it would be neat to do a direct migration from the legacy database to the new Cedar database, but I did not get it working). You need to install the taps-gem in order to do any dumping. Taps will dump the database into your development database unless you provide an connection string to another database:

# use sqlite for dumping and do it into a separate file
heroku db:pull sqlite://dump.db

# mv the file to your Cedar application and push it
heroku db:push sqlite://dump.db

Config variables

If you have custom config variables in your application it’s pretty easy to move them into the new environment:

# list all config values of the legacy app in console format
heroku config -s

# replace the newlines with whitespaces and
# append all the configuration variables of 
# your new Cedar app at the end or remove the
# ones that you do not want to migrate!

# add the list of values to your Cedar app
heroku config:add KEY=VALUE KEY2=VALUE2 [...]

Installing addons

It’s also most likely that you want to use the same addons than in your legacy application:

# list your addons in the legacy app
heroku addons

# install all addons separately in the Cedar app
heroku addons:add apigee:basic
heroku addons:add cron:daily
[...]

Sendgrid

If you are using the Sendgrid Addon you should be aware that the automatic configuration is not working anymore the Cedar Stack! You need to configure it in your app:

  # config/environments/production.rb
  config.action_mailer.raise_delivery_errors = true
  config.action_mailer.smtp_settings = {
    :address        => "smtp.sendgrid.net",
    :port           => "25",
    :authentication => :plain,
    :user_name      => ENV['SENDGRID_USERNAME'],
    :password       => ENV['SENDGRID_PASSWORD'],
    :domain         => ENV['SENDGRID_DOMAIN']
  }

Switching domains

Before you do the last step, you should have a look if everything is up and running:

heroku open

If everything is fine, you can move all the domains from the legacy application to your new and shiny Cedar Stack application:

# list domains in legacy app
heroku domains

# and remove them
heroku domains:remove hamburg.onruby.de
heroku domains:remove onruby.de
[...]

# re-add them to Cedar application
heroku domains:add hamburg.onruby.de
heroku domains:add onruby.de
[...]

Looking at the result is quite disappointing, because nothing has changed for the user, but everything is new and shiny from the inside!

If you have any other pointers of what you need to do for migrating your application please feel free to add a comment!