About Procfiles

Use a Procfile to define the process that is invoked when a container starts. The Procfile can override the default start process for any language type. Procfile support is provided by the entrypoint buildpack.

Procfile name and location

The Procfile is always a plain text file without a file extension.

Google Cloud's buildpacks searches for a file named Procfile at the root folder of the project. The Procfile must live in your project's root directory and cannot be placed anywhere else.

Procfile format

A Procfile declares its process types on individual lines, each with the following format:

PROCESS_TYPE: COMMAND

Replace:

  • PROCESS_TYPE with an alphanumeric name for your command, such das web, worker and custom.
  • COMMAND indicates the command that every process type should execute on startup, such as gunicorn -b :$PORT main:app.