github-action-push-to-another-repository/README.md

# github-action-push-to-another-repository

This GitHub Action will help to push files that exist in a GitHub repository or that are generated by another GitHub action into a new repository.

Please read the documentation to understand which files and commits are kept in the destination repository and `target-directory`.

Two examples, on a git push in `source` repository you want certain files to be pushed into `destination` repository:
 * Specify a directory in the `source` to be pushed to `destination`  
 * Generate some files using another GitHub Action (e.g. MarkDown to PDF) and you want to push the PDFs across

`source` or `destination` can be private.

## Table of contents

* [General flow](#general_flow)

## General flow

There are two examples:
 * Using SSH deploy keys (recommended, a bit harder to setup): [push-to-another-repository-deploy-keys-example](https://github.com/cpina/push-to-another-repository-deploy-keys-example). The configuration is in the file [.github/workflows/ci.yml](https://github.com/cpina/push-to-another-repository-deploy-keys-example/blob/main/.github/workflows/ci.yml#L21)
 * Using a Personal Access Token (first style, not recommended but easier to setup: [push-to-another-repository-example](https://github.com/cpina/push-to-another-repository-example). The configuration is in the file [.github/workflows/ci.yml](https://github.com/cpina/push-to-another-repository-example/blob/main/.github/workflows/ci.yml#L21)

In those examples the file [build.sh](https://github.com/cpina/push-to-another-repository-deploy-keys-example/blob/main/build.sh) is executes which creates a new directory `output/` and this directory is copied across the [destination repository](https://github.com/cpina/push-to-another-repository-output)

Before using the GitHub Action **it is needed to set up either the Personal Access Token or the SSH Keys as described below.**

:warning: Please bear in mind: files in the target repository's specified directory are deleted unless the option `target-directory` is used (in this case only the files for this directory are deleted).

There are different variables to set up the behaviour:

## Usage
### `source-directory` (argument)
Directory that the GitHub Action will push files from. Note: it can be `.` to push all the repository but read the FAQ!

### `destination-github-username` (argument)
To output to a repository such as `https://github.com/cpina/push-to-another-repository-output` this variable would be `cpina`.

### `destination-repository-name` (argument)
To output to a repository such as `https://github.com/cpina/push-to-another-repository-output` this variable would be `push-to-another-repository-output`

:warning:: the GitHub Action currently deletes all the files and directories in the destination repository. The idea is to copy from an `output` directory into the `destination-repository-name` having a copy without any previous files there.

### `user-email` (argument)
The email that will be used for the commit in the destination-repository-name. Used for the "Author" of the generated commit.

### `user-name` (argument) [optional]
The name that will be used for the commit in the destination-repository-name. If not specified, the `destination-github-username` will be used instead.

### `destination-repository-username` (argument) [optional]
The Username/Organization for the destination repository, if different from `destination-github-username`. For the repository `https://github.com/cpina/push-to-another-repository-output` is `cpina`.

### `target-branch` (argument) [optional]
The branch name for the destination repository. It defaults to `main`.

### `commit-message` (argument) [optional]
The commit message to be used in the output repository. Optional and defaults to "Update from $REPOSITORY_URL@commit".

The string `ORIGIN_COMMIT` is replaced by `$REPOSITORY_URL@commit`.

### `target-directory` (argument) [optional]
The directory to wipe and replace in the target repository.  Defaults to wiping the entire repository

## Setup
### `SSH_DEPLOY_KEY` Vs. `API_TOKEN_GITHUB`
The action, entirely executed in your GitHub continuous integration environment, needs to be able to push to the destination repository.

There are two options to do this:
 * Create an SSH deploy key. This key is restricted to the destination repository only
 * Create a GitHub Personal Authentication Token: the token has access to all your repositories

Someone with write access to your repository or this action, could technically add code to leak the key. Thus, *it is recommended to use the SSH deploy key method to minimise repercusions* if this was the case.

This action supports both methods to keep backwards compatibility, because in the beginning it only supported the GitHub Personal Authentication token.

### Set up using SSH deploy key
#### Generate the key files

* `ssh-keygen -t ed25519 -C "your_email@example.com"` (the type ed25519 is recommended by [GitHub documentation](https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent#generating-a-new-ssh-key))
* ssh will ask for a file path: `Enter file in which to save the key`: write a new file name. I suggest the default directory and as a filename: `id_github_name_of_your_repository` to avoid overwriting a previous file. If you will be using this action for multiple repositories, you might want to generate different keys for each one. 
* Leave the passphrase empty (otherwise we would need to pass the passphrase to the GitHub Action)

#### Set up the deployment key

#### Destination repository

* Go to the GitHub page of the destination repository
* Click on "Settings" (settings for the repository, not the account settings)
* On the left-hand side pane click on "Deploy keys"
* Click on "Add deploy key"
* Title: "GitHub Action push to another repository"
* Key: paste the contents of the file with the public key. This was generated in the "Generate the key files" step and the name is "id_github_name_of_your_repository.pub"
* Enable "Allow write access"barbar

#### Origin repository

* Go to the GitHub page of the origin repository
* On the left-hand side pane click on "Secrets" and then on "Actions"
* Click on "New repository secret"
* Name: "SSH_DEPLOY_KEY"
* Value: paste the contents of the file with the private key. This was generated in the "Generate the key files" step and the name is "id_github_name_of_your_repository"

### Set up using personal access token

You don't need to do this if you chose to set up the deploy keys using the steps above. This method is here for compatibility with the initial approach of this GitHub Action. The personal access token would have access to all your repositories, so if it were to be leaked the damage would be greater.

Generate your personal token following the steps:
* Go to the GitHub Settings (on the right-hand side on the profile picture)
* On the left-hand side pane click on "Developer Settings"
* Click on "Personal Access Tokens" (also available at https://github.com/settings/tokens)
* Generate a new token, choose "Repo". Copy the token.

Then make the token available to the Github Action following the steps:
* Go to the GitHub page for the repository that you push from. Click on "Settings"
* On the left-hand side pane click on "Secrets" then "Actions"
* Click on "New repository secret"
* Name: "API_TOKEN_GITHUB"
* Value: paste the token that you copied earlier

#### Example usage
```yaml
      - name: Pushes to another repository
        uses: cpina/github-action-push-to-another-repository@main
        env:
          SSH_DEPLOY_KEY: ${{ secrets.SSH_DEPLOY_KEY }}
          API_TOKEN_GITHUB: ${{ secrets.API_TOKEN_GITHUB }}
        with:
          source-directory: 'output'
          destination-github-username: 'cpina'
          destination-repository-name: 'pandoc-test-output'
          user-email: carles3@pina.cat
          target-branch: main
```
(you only need `SSH_DEPLOY_KEY` or `API_TOKEN_GITHUB` depending on the method that you used)

Working example:

https://github.com/cpina/push-to-another-repository-deploy-keys-example/blob/main/.github/workflows/ci.yml

It generates files from:
https://github.com/cpina/push-to-another-repository-deploy-keys-example

To:
https://github.com/cpina/push-to-another-repository-output


## Troubleshooting

## FAQ