Legacy Rails Apps

Example: Minnestar Sessionizer

Back Story

  • The Minnestar has an annual 1-day conference called Minnebar.
  • Minnestar has a Sessionizer app in which participants can add Minnebar sessions, and an algorithm provides a time slot and room for these sessions.
  • The collaborators prefer the Vagrant setup. My way is much faster. Using Docker instead of Vagrant means faster performance and not having to wait for a bootup process to finish.
  • Because I am not a collaborator, I contribute through my fork and with pull requests. In my fork, I do my development in my ruby_on_racetracks branch, which contains my Ruby on Racetracks elements. I use the "git cherry-pick" command for creating pull requests that provide the desired changes to the mainline code while keeping my Ruby on Racetracks elements out.
  • Please note that the "src" directory in the sessionizer app is the root directory of the Rails app.

Fresh Start

  • If you have not already done so, install Docker on your machine. More details are covered in the Different Docker Tutorial.
  • If you still have the jhsu802701 directory, delete it.
  • Enter the following commands in LXTerminal:
cd
mkdir jhsu802701
cd jhsu802701
git clone https://gitlab.com/jhsu802701/docker-debian-stretch-use
cd docker-debian-stretch-use
sh rvm-rails-sessionizer.sh
  • When prompted for a port offset value, enter "13".
  • Enter the command "cd rvm-rails-sessionizer; sh download_new_image.sh" and follow the instructions.
  • It will take a few minutes to download the Docker image. When the process is finished, a Docker container will be created for you, and you will be automatically logged in.

Database Configuration

  • The config/database.yml file is different for the ruby_on_racetracks branch. In this branch, no username or password is specified. This allows the command "bundle exec rake app:make_believe" to work.
  • The configuration of the master branch requires that your OS username be "vagrant". If your OS username is anything else, the "bundle exec rake app:make_believe" command won't work, and you will be unable to seed the database.

Setting Up The App

  • In Docker, enter the following commands:
git clone https://github.com/jhsu802701/sessionizer
cd sessionizer
git checkout ruby_on_racetracks
cd src
sh build_fast.sh; sh server.sh
  • The build_fast.sh script installs the gems, configures the PostgreSQL database, and runs the tests. This process takes just a few minutes. If all goes well, all of the tests will pass.

Viewing the App

  • In a few minutes, the build process will be finished, and you will see the Rails server running.
  • Because you chose a port offset value of 13, port 3000 in Docker is linked to port 3013 in your desktop Linux system. The ports.txt file in the shared directory lists the port assignments.
  • Go to http://localhost:3013/ to view the app.

Viewing the App's Database

  • Open pgAdmin in your desktop Linux setup to view the data in the app.
  • Because you chose a port offset value of 13, port 5432 in Docker is linked to port 15445 in your desktop Linux system. The ports.txt file in the shared directory lists the port assignments.
  • In the upper left corner of the pgAdmin window, click on the plug icon to add a server.
  • Fill in the following server parameters:
    • Name: sessionizer
    • Host: localhost
    • Port: 15445
    • Username: postgres
  • In the Object browser, go to Server Groups -> Servers -> sessionizer -> Databases -> sessionizer_development -> schemas -> public - Tables. Right-click on the desired object and go to View Data -> View All Rows. You can now see the data.
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