where do github apps run and what are the resources limits

Question

i am interested in building a github app. reading through github Setting up your development environment to create a GitHub App documentation it explains that a github app is based on a http server which will handle webhooks.

yet, on every github app i installed, the app\installation did not require anything that involves hosting and/or creation of http server in order to deploy the app to my github accout.

for such github apps, which are installed directly through the github marketplace (you can take probot stale and rennovate as examples for such apps)

1. where do these application run? (e.g.; does github deploys the app on a dedicate (virtual) server?).
2. what are the resources limitations for such apps (amount of memory, cpu, etc.?)
3. how can the github app logs be accessed by the github account owner who installed such app?

links for reference and an answer will be great.

Answer 1

GitHub App is just another app that you create. GitHub apps are treated as first-class citizens when it comes to integrating with GitHub. One can use Nodejs , Ruby, etc to build the App. Once the app is ready it can be hosted on a Server just like any other server hosted apps. You register your app on GitHub by providing relevant details.

So, coming to your questions.

1. The Apps can run on any hosting service of your choice. It can be a Windows Server, Heroku, etc.
2. I believe it is only limited by the resource of your server or the hosting service provider that you chose. However you might be ineterset in erading more about the Rate Limit More on Rate limits here.
3. GitHub app logs are something which only the developer will be able to see. To the end user ,i.e. the repo owner who installed the GitHUb app on his repos, all that will be available are the checks , statuses and any other details that the developer of app decided to display.

A very handy guide on Deployment and other details : Probot Documentation. This documentation is great if you are planning to use the probot framework for developing your github apps, but most of the instructions still stand true in case you decide to pick up a different tech stack.

Answer 2

The most important thing to realise about a (so-called?) Github App is that the App itself does not run anywhere - or at least that is what I would argue. Basically Github Apps are two linked mechanisms, both a bit of infrastructure. The first of these mechanisms is access control, essentially replacing use of user PATs - you can give relatively fine grained access to repos that the App is installed in, rather than just giving access to all repos the user can access. The second mechanism is that of webhooks - generating events as requested.

What Github Apps do not directly provide is the bit between this - handling the webhooks and generating API calls using the App for access. Basically you are on your own and need to do it yourself. The plus, @asif-kamran-malick mentioned, is that you have freedom to implement it how you see fit.

One alternative possibility is that the App itself, rather than setting to handle ongoing Webhooks, runs on installation and looks to add Actions into the repo. Never done it, but some of the github examples seem to work this way. Of course, Actions are run within Github environments and are potentially subject to resource limits. Apart from this though, Actions are a completely separate "beast" and should not be confused.