What is Procfile? and Web and Worker

Question

Is it necessary to give 'worker' information in Procfile? If yes then what it is actually? I have already added web: node server/server.js detail in the Procfile.

Skricki

Answer 1

Procfile is a mechanism for declaring what commands are run by your application’s dynos on the Heroku platform.

From Process Types and the Procfile, which is a good introduction, but basically you use the Procfile to tell Heroku how to run various pieces of your app. The part to the left of the colon on each line is the process type; the part on the right is the command to run to start that process.

Process types can be anything, although web is special, as Heroku will route HTTP requests to processes started with the web name. Other processes, such as background workers, can be named anything, and you can use the Heroku toolbelt to start or stop those processes by referring to its name.

So, in short, worker is not necessary, unless you want to run some other process in the background by controlling process with the heroku ps command.

Kalasky

blog.daviddollar.org/2011/05/06/introducing-foreman.html This too, is a nice introduction to the subject. – Mangan

@Mangan Good call. It's worth noting that the Heroku Toolbelt will install Foreman locally so you can use the same Procfile to run your own apps in development. – Kalasky

Hey guys, actually I am getting one error and I posted it here - It would be great if you can have a look into this. I scratched my head to solve this but failed. #16130125 – Skricki

Procfiles are to configure foreman, right? So technically you could run foreman anywhere, not just on Heroku? – Dumyat

Thanks for for Other processes, such as background workers, can be named anything - facts like these are important but often overlooked – Paraglider

Answer 2

You would only need a 'worker' entry in your Procfile if you plan on using some sort of background job system (i.e. queuing long running tasks for later). Heroku has more information here:

https://devcenter.heroku.com/articles/procfile

Keshiakesia

Also, the name "worker" is arbitrary. You can name them whatever you want in your procfile; "worker", "emailer", "sidekiq", "ladygaga_twitter_feed_watcher". This allows you to manage each type independently ($ heroku ps:scale emailer=2). In fact, if there are multiple "worker" types in a procfile, only the one listed last will be used. – Whitcher

@Whitcher For sure. I believe Heroku sets up some defaults to worker (for Rails apps it might run rake jobs:work) but other than that the name is for the user. – Keshiakesia

Answer 3

I was following Udemy course regarding nestjs and aws Elastic Beanstalk to deploy however it keeps failing to deploy until I created Procfile with following:

web: npm install && npm run-script build && npm run-script start:prod

Yacht

You should use release: for the first two commands since if they fail, it will not deploy the new build. web is special as Heroku will route things like HTTP requests to web processes, so that's certainly overkill for the first two. – Tutto