Buildfile and Procfile

Some platforms allow you to customize how you build or prepare your application, and to specify the processes that run your application. Each individual platform topic specifically mentions Buildfile and/or Procfile if the platform supports them. Look for your specific platform under Elastic Beanstalk platforms.

For all supporting platforms, syntax and semantics are identical, and are as described on this page. Individual platform topics mention specific usage of these files for building and running applications in their respective languages.

Buildfile

To specify a custom build and configuration command for your application, place a file named Buildfile in the root directory of your application source. The file name is case sensitive. Use the following syntax for your Buildfile.

<process_name>: <command>

The command in your Buildfile must match the following regular expression: ^[A-Za-z0-9_-]+:\s*[^\s].*$

Elastic Beanstalk doesn't monitor the application that is run with a Buildfile. Use a Buildfile for commands that run for short periods and terminate after completing their tasks. For long-running application processes that should not exit, use a Procfile.

All paths in the Buildfile are relative to the root of the source bundle. In the following example of a Buildfile, build.sh is a shell script located at the root of the source bundle.

make: ./build.sh

If you want to provide custom build steps, we recommend that you use predeploy platform hooks for anything but the simplest commands, instead of a Buildfile. Platform hooks allow richer scripts and better error handling. Platform hooks are described in the next section.

Procfile

To specify custom commands to start and run your application, place a file named Procfile in the root directory of your application source. The file name is case sensitive. Use the following syntax for your Procfile. You can specify one or more commands.

<process_name1>: <command1>
<process_name2>: <command2>
...

Each line in your Procfile must match the following regular expression: ^[A-Za-z0-9_-]+:\s*[^\s].*$

Use a Procfile for long-running application processes that shouldn't exit. Elastic Beanstalk expects processes run from the Procfile to run continuously. Elastic Beanstalk monitors these processes and restarts any process that terminates. For short-running processes, use a Buildfile.

All paths in the Procfile are relative to the root of the source bundle. The following example Procfile defines three processes. The first one, called web in the example, is the main web application.

web: bin/myserver
cache: bin/mycache
foo: bin/fooapp

Elastic Beanstalk configures the proxy server to forward requests to your main web application on port 5000, and you can configure this port number. A common use for a Procfile is to pass this port number to your application as a command argument. For details about proxy configuration, see Reverse proxy configuration.

Elastic Beanstalk captures standard output and error streams from Procfile processes in log files. Elastic Beanstalk names the log files after the process and stores them in /var/log. For example, the web process in the preceding example generates logs named web-1.log and web-1.error.log for stdout and stderr, respectively.