GitHub Apps with GitHub Actions, How is that supposed to work

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I'm in the process of learning GitHub Actions to a professional level. Learning has been harder than I thought it would be. I've read the GitHub Actions documentation, some pages like 5 times, then there are pages that link to other pages, then I realize I've looped. I've been working to complete my first GitHub Actions for a few months now. Its getting better. Here are a few question I'm trying to get answered:

1. Why are they advertising that we should replace fine-grained access tokens with GitHub Apps?
2. In order to use a GitHub App, as a means of authentication so that it can write back to repositories; I know that I do not need to have an app running on a server somewhere, but then how can I access my RSA pem file so that I can generate a JWT?
3. When running a GitHub App and trying to request an installation token, how can I know which org or user I'm running (I suspect GitHub context is needed here)?
4. Why is GitHub Apps authentication a chicken/egg or catch-22 situation?

[Aestivial]

A GitHub App is usually recommended over a PAT for automation because the token is installation-scoped, permission-scoped, and short-lived. A PAT is tied to a user account; a GitHub App can act as its own bot identity and can be installed only on the orgs/repos it needs.

For Actions, you usually do not need to hand-roll the JWT flow. Store the app private key as an Actions secret, store the app/client ID as a variable, then mint an installation token inside the workflow:

steps:
  - uses: actions/create-github-app-token@v3
    id: app-token
    with:
      client-id: ${{ vars.APP_CLIENT_ID }}
      private-key: ${{ secrets.APP_PRIVATE_KEY }}
      owner: ${{ github.repository_owner }}

  - run: gh api /repos/${{ github.repository }}
    env:
      GH_TOKEN: ${{ steps.app-token.outputs.token }}

That answers the private-key part: the PEM is not read from a server; it is stored as a GitHub Actions secret and passed only to the token-generation step.

For the owner/org question, ${{ github.repository_owner }} is usually the right starting point. If the App is installed somewhere else, pass that owner explicitly. The app must already be installed on the target org/user/repositories, and its permissions must include whatever you are trying to do.

So the flow is:

1. Create the GitHub App.
2. Grant it the minimum needed permissions.
3. Install it on the target account/repos.
4. Save the private key as APP_PRIVATE_KEY.
5. Use actions/create-github-app-token to get a short-lived installation token.
6. Use that token for gh, API calls, checkout, commits, comments, etc.

It feels like a chicken-and-egg problem at first, but the bootstrap secret is only the app’s private key. After that, each workflow run creates a short-lived installation token.

Docs:

• https://docs.github.com/en/apps/creating-github-apps/authenticating-with-a-github-app/generating-a-json-web-token-jwt-for-a-github-app
• https://github.com/actions/create-github-app-token

If this clears it up, please mark it as the answer so future Actions/App users can find the pattern.

[jeman-arcanist]

A concise answer to each of your questions:

1. Why GitHub Apps over fine-grained PATs?

   • GitHub Apps are designed for automation. They provide:

     • Short-lived installation tokens (typically valid for 1 hour).
     • Granular, per-repository permissions.
     • Easy revocation or installation on selected repositories.
     • No dependency on a user's personal account or credentials.

   • This makes them more secure and manageable than PATs, especially for CI/CD and organization-wide automation.

2. How do you access the private key in GitHub Actions?

   • You don't keep the PEM file on disk. Instead:

     • Store the app's private key as an encrypted GitHub Actions secret (e.g. APP_PRIVATE_KEY).
     • Store the App ID as another secret or variable.
     • During the workflow, reconstruct the key from the secret and use it to generate the JWT.

   • Many people use actions like actions/create-github-app-token so they don't need to implement the JWT flow themselves.

3. How do you know which installation to use?

   • The workflow context tells you the repository (github.repository) and owner (github.repository_owner).
   • If your app is installed on that repository, you can request an installation token for that installation. Helper actions usually discover the correct installation automatically from the repository context.

4. Why does it seem like a chicken-and-egg problem?

   • It can feel that way initially, but the authentication flow is:

     1. Store the App ID and private key as GitHub secrets.
     2. Generate a JWT using the private key.
     3. Exchange the JWT for an installation access token.
     4. Use the installation token to call the GitHub API.

   • The only long-lived secret is the private key, which GitHub Actions securely injects into the workflow. Everything else is generated dynamically.

If you're just getting started, I'd recommend using actions/create-github-app-token instead of implementing the JWT and installation token flow yourself. Once you're comfortable with GitHub Actions, reading through that action's source can help you understand the underlying authentication process. It abstracts away the boilerplate while still following the official GitHub App authentication flow.

[farhan2t24]

These are common questions when moving from PATs to GitHub Apps. Here's the general idea:

Why GitHub Apps instead of fine-grained PATs? GitHub Apps provide more granular, repository-specific permissions, short-lived installation tokens, and better auditing. They're generally considered more secure than long-lived personal access tokens.

Where does the private key (.pem) go? In GitHub Actions, you typically store the private key as an encrypted repository or organization secret. The workflow reads that secret at runtime to generate the JWT—there's no need for a continuously running server just for authentication.

How do you know which installation to use? The workflow context (such as the repository owner and repository name) can be used to determine the appropriate installation. If your app is installed on multiple accounts, you may need to query the GitHub API to find the matching installation before requesting an installation token.

Why does it feel like a chicken-and-egg problem? It can seem that way initially because you need a JWT to request an installation token, but the JWT is created locally using your app's private key. Once you have the installation token, you authenticate API requests as the app installation rather than as a user.