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Process/Container management

Dokku supports rudimentary process (really container) management via the ps plugin.

ps <app>                                        List processes running in app container(s)
ps:rebuildall                                   Rebuild all apps
ps:rebuild <app>                                Rebuild an app
ps:restartall                                   Restart all deployed app containers
ps:restart <app>                                Restart app container(s)
ps:scale <app> <proc>=<count> [<proc>=<count>]  Set how many processes of a given process to run
ps:start <app>                                  Start app container(s)
ps:stop <app>                                   Stop app container(s)

NOTE: As of v0.3.14, dokku deploy:all in now deprecated by ps:restartall and will be removed in a future version.

Scaling

Dokku allows you to run multiple process types at different container counts. For example, if you had an app that contained 1 web app listener and 1 background job processor, dokku can, spin up 1 container for each process type defined in the Procfile. By default we will only start the web process. However, if you wanted 2 job processors running simultaneously, you can modify this behavior in a few ways.

DOKKU_SCALE file

You can optionally create a DOKKU_SCALE file in the root of your repository. Dokku expects this file to contain one line for every process defined in your Procfile. Example: 

web=1
worker=2

ps:scale command

Dokku can also manage scaling itself via the ps:scale command. This command can be used to scale multiple process types at the same time.

dokku ps:scale app_name web=1 worker=2

NOTE: Dokku will always use the DOKKU_SCALE file that ships with the repo to override any local settings.

The web proctype

Like Heroku, we handle the web proctype differently from others. The web proctype is the only proctype that will invoke custom checks as defined by a CHECKS file. It is also the only proctype that will be launched in a container that is either proxied via nginx or bound to an external port.