Add push to remote mirror repository (#15157)

* Added push mirror model.

* Integrated push mirror into queue.

* Moved methods into own file.

* Added basic implementation.

* Mirror wiki too.

* Removed duplicated method.

* Get url for different remotes.

* Added migration.

* Unified remote url access.

* Add/Remove push mirror remotes.

* Prevent hangs with missing credentials.

* Moved code between files.

* Changed sanitizer interface.

* Added push mirror backend methods.

* Only update the mirror remote.

* Limit refs on push.

* Added UI part.

* Added missing table.

* Delete mirror if repository gets removed.

* Changed signature. Handle object errors.

* Added upload method.

* Added "upload" unit tests.

* Added transfer adapter unit tests.

* Send correct headers.

* Added pushing of LFS objects.

* Added more logging.

* Simpler body handling.

* Process files in batches to reduce HTTP calls.

* Added created timestamp.

* Fixed invalid column name.

* Changed name to prevent xorm auto setting.

* Remove table header im empty.

* Strip exit code from error message.

* Added docs page about mirroring.

* Fixed date.

* Fixed merge errors.

* Moved test to integrations.

* Added push mirror test.

* Added test.

1 files changed, 88 insertions, 0 deletions

diff --git a/docs/content/doc/advanced/repo-mirror.en-us.md b/docs/content/doc/advanced/repo-mirror.en-us.md
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+---
+date: "2021-05-13T00:00:00-00:00"
+title: "Repository Mirror"
+slug: "repo-mirror"
+weight: 45
+toc: false
+draft: false
+menu:
+  sidebar:
+    parent: "advanced"
+    name: "Repository Mirror"
+    weight: 45
+    identifier: "repo-mirror"
+---
+
+# Repository Mirror
+
+Repository mirroring allows for the mirroring of repositories to and from external sources. You can use it to mirror branches, tags, and commits between repositories.
+
+**Table of Contents**
+
+{{< toc >}}
+
+## Use cases
+
+The following are some possible use cases for repository mirroring:
+
+- You migrated to Gitea but still need to keep your project in another source. In that case, you can simply set it up to mirror to Gitea (pull) and all the essential history of commits, tags, and branches are available in your Gitea instance.
+- You have old projects in another source that you don’t use actively anymore, but don’t want to remove for archiving purposes. In that case, you can create a push mirror so that your active Gitea repository can push its changes to the old location.
+
+## Pulling from a remote repository
+
+For an existing remote repository, you can set up pull mirroring as follows:
+
+1. Select **New Migration** in the **Create...** menu on the top right.
+2. Select the remote repository service.
+3. Enter a repository URL.
+4. If the repository needs authentication fill in your authentication information.
+5. Check the box **This repository will be a mirror**.
+5. Select **Migrate repository** to save the configuration.
+
+The repository now gets mirrored periodically from the remote repository. You can force a sync by selecting **Synchronize Now** in the repository settings.
+
+## Pushing to a remote repository
+
+For an existing repository, you can set up push mirroring as follows:
+
+1. In your repository, go to **Settings** > **Repository**, and then the **Mirror Settings** section.
+2. Enter a repository URL.
+3. If the repository needs authentication expand the **Authorization** section and fill in your authentication information.
+4. Select **Add Push Mirror** to save the configuration.
+
+The repository now gets mirrored periodically to the remote repository. You can force a sync by selecting **Synchronize Now**. In case of an error a message displayed to help you resolve it.
+
+:exclamation::exclamation: **NOTE:** This will force push to the remote repository. This will overwrite any changes in the remote repository! :exclamation::exclamation:
+
+### Setting up a push mirror from Gitea to GitHub
+
+To set up a mirror from Gitea to GitHub, you need to follow these steps:
+
+1. Create a [GitHub personal access token](https://docs.github.com/en/github/authenticating-to-github/creating-a-personal-access-token) with the *public_repo* box checked.
+2. Fill in the **Git Remote Repository URL**: `https://github.com/<your_github_group>/<your_github_project>.git`.
+3. Fill in the **Authorization** fields with your GitHub username and the personal access token.
+4. Select **Add Push Mirror** to save the configuration.
+
+The repository pushes shortly thereafter. To force a push, select the **Synchronize Now** button.
+
+### Setting up a push mirror from Gitea to GitLab
+
+To set up a mirror from Gitea to GitLab, you need to follow these steps:
+
+1. Create a [GitLab personal access token](https://docs.gitlab.com/ee/user/profile/personal_access_tokens.html) with *write_repository* scope.
+2. Fill in the **Git Remote Repository URL**: `https://<destination host>/<your_gitlab_group_or_name>/<your_gitlab_project>.git`.
+3. Fill in the **Authorization** fields with `oauth2` as **Username** and your GitLab personal access token as **Password**.
+4. Select **Add Push Mirror** to save the configuration.
+
+The repository pushes shortly thereafter. To force a push, select the **Synchronize Now** button.
+
+### Setting up a push mirror from Gitea to Bitbucket
+
+To set up a mirror from Gitea to Bitbucket, you need to follow these steps:
+
+1. Create a [Bitbucket app password](https://support.atlassian.com/bitbucket-cloud/docs/app-passwords/) with the *Repository Write* box checked.
+2. Fill in the **Git Remote Repository URL**: `https://bitbucket.org/<your_bitbucket_group_or_name>/<your_bitbucket_project>.git`.
+3. Fill in the **Authorization** fields with your Bitbucket username and the app password as **Password**.
+4. Select **Add Push Mirror** to save the configuration.
+
+The repository pushes shortly thereafter. To force a push, select the **Synchronize Now** button.