Configuring custom start commands with a Procfile on Elastic Beanstalk - AWS Elastic Beanstalk

Configuring custom start commands with a Procfile on Elastic Beanstalk

To specify custom commands to start a Go application, include a file called Procfile at the root of your source bundle.

For details about writing and using a Procfile, see Buildfile and Procfile.

Example Procfile
web: bin/server
queue_process: bin/queue_processor
foo: bin/fooapp

You must call the main application web, and list it as the first command in your Procfile. Elastic Beanstalk exposes the main web application on the root URL of the environment; for example, http://my-go-env.elasticbeanstalk.com.

Elastic Beanstalk also runs any application whose name does not have the web_ prefix, but these applications are not available from outside of your instance.

Elastic Beanstalk expects processes run from the Procfile to run continuously. Elastic Beanstalk monitors these applications and restarts any process that terminates. For short-running processes, use a Buildfile command.

If your Elastic Beanstalk Go environment uses an Amazon Linux AMI platform version (preceding Amazon Linux 2), read the additional information in this section.

Notes

  • The information in this topic only applies to platform branches based on Amazon Linux AMI (AL1). AL2023/AL2 platform branches are incompatible with previous Amazon Linux AMI (AL1) platform versions and require different configuration settings.

  • On July 18,2022, Elastic Beanstalk set the status of all platform branches based on Amazon Linux AMI (AL1) to retired. For more information about migrating to a current and fully supported Amazon Linux 2023 platform branch, see Migrating your Elastic Beanstalk Linux application to Amazon Linux 2023 or Amazon Linux 2.

Note

The information in this topic only applies to platform branches based on Amazon Linux AMI (AL1). AL2023/AL2 platform branches are incompatible with previous Amazon Linux AMI (AL1) platform versions and require different configuration settings.

Elastic Beanstalk configures the nginx proxy to forward requests to your application on the port number specified in the PORT environment property for your application. Your application should always listen on that port. You can access this variable within your application by calling the os.Getenv("PORT") method.

Elastic Beanstalk uses the port number specified in the PORT environment property for the port for the first application in the Procfile, and then increments the port number for each subsequent application in the Procfile by 100. If the PORT environment property is not set, Elastic Beanstalk uses 5000 for the initial port.

In the preceding example, the PORT environment property for the web application is 5000, the queue_process application is 5100, and the foo application is 5200.

You can specify the initial port by setting the PORT option with the aws:elasticbeanstalk:application:environment namespace, as shown in the following example. 

option_settings:
  - namespace:  aws:elasticbeanstalk:application:environment
    option_name:  PORT
    value:  <first_port_number>

For more information about setting environment properties for your application, see Option settings.