Configuring the production server for Cloud Foundry apps

You can configure a production server for your apps in Cloud Foundry.

When you deploy an app, Cloud Foundry determines the command that is used to start the app through the following process:

1. If you use the command cf push -c COMMAND, then Cloud Foundry uses COMMAND to start the app.

2. If you create a file called a Procfile, Cloud Foundry uses Procfile to configure the command that launches the app. See About Procfiles.

3. If you do not use cf push -c COMMAND and do not create a Procfile, then Cloud Foundry does one of the following, depending on the buildpack:

   • Uses a default start command.
   • Fails to start the app and shows a warning that the app is missing a Procfile.

Procfiles

Use a Procfile to specify a start command for buildpacks when a default start command is not provided. Some buildpacks use Python to work on a variety of frameworks and do not attempt to provide a default start command.

Another reason to use a Procfile is to configure a production server for web apps.

When you use a Procfile, you declare required runtime processes, and called process types, for your web app. Process managers in a server use the process type to run and manage the workload.

In a Procfile, you declare one process type per line and use the following syntax:

PROCESS-TYPE: COMMAND

Where:

• PROCESS-TYPE is web. A web process handles HTTP traffic.
• COMMAND is the command line to launch the process.

For example, a Procfile with the following content starts the launch script created by the build process for a Java app:

web: build/install/MY-PROJECT-NAME/bin/MY-PROJECT-NAME

Procfile support is integrated into the buildpack lifecycle. However, due to differing behavior of buildpacks, it might not be suitable with all buildpacks.

Procfiles can be used with the following buildpacks:

• Binary buildpack

• .NET Core buildpack

• Go buildpack

• NGINX buildpack

• Node.js buildpack

• Python buildpack

• R buildpack

• Ruby buildpack

Specifying a web server

Follow these steps to specify a web server using a Procfile. For more information about configuring a web server for Rails apps, see Configuring a Ruby web server.

1. Create a blank file with a command line for a web process type.

2. Save it as a file named Procfile with no extension in the root directory of your app.

3. Push your app.

Configuring a Ruby web server

Cloud Foundry uses the default standard Ruby web server library WEBrick for Ruby and Ruby on Rails apps. However, Cloud Foundry can support a more robust production web server. For example, Phusion Passenger, Puma, Thin, or Unicorn.

To instruct Cloud Foundry to use a web server other than WEBrick, use the following steps:

1. Add the gem for the web server to your Gemfile.

2. In the config directory of your app, create a new configuration file or modify an existing file. See your web server documentation for how to configure this file.

   The following example uses the Puma web server:

       # config/puma.rb
       threads 8,32
       workers 3
       
   
       on_worker_boot do
       # things workers do
       end
   

3. In the root directory of your app, create a Procfile and add a command line for a web process type that points to your web server. For information about configuring the specific command for a process type, see your web server documentation.
   
   

   The following example shows a command that starts a Puma web server and specifies the app runtime environment, TCP port, paths to the server state information, and configuration files:

   web: bundle exec puma -e $RAILS_ENV -p 1234 -S ~/puma -C config/puma.rb