Add backup document (#89)

* Added backup document

* Improve and reference backup docs

Co-authored-by: matto <matto@matto.nl>
Co-authored-by: Sascha Ißbrücker <sissbruecker@lyska.io>

README.md

@@ -80,11 +80,7 @@ The application runs in a web-server called [uWSGI](https://uwsgi-docs.readthedo
 
 ### Backups
 
-For backups you have two options: manually or automatic.
+Check the [backups document](docs/backup.md) for options on how to create backups.
-
-For manual backups you can export your bookmarks from the UI and store them on a backup device or online service.
-
-For automatic backups you want to backup the applications database. As described above, for production setups you should [mount](https://stackoverflow.com/questions/23439126/how-to-mount-a-host-directory-in-a-docker-container) the `/etc/linkding/data` directory from the Docker container to a directory on your host system. You can then use a backup tool of your choice to backup the contents of that directory.
 
 ## API
 

docs/backup.md

@@ -0,0 +1,52 @@
+# Backups
+
+This page describes some options on how to create backups.
+
+## What to backup
+
+Linkding stores all data in a SQLite database, so all you need to backup are the contents of that database.
+
+The location of the database file is `data/db.sqlite3` in the application folder. 
+If you are using Docker then the full path in the Docker container is `/etc/linkding/data/db.sqlite`. 
+As described in the installation docs, you should mount the `/etc/linkding/data` folder to a folder on your host system, from which you then can execute the backup.
+
+Below, we describe two methods to create a backup of the database:
+
+- Manual backup using the export function from the UI
+- Create a copy of the SQLite databse with the SQLite backup function
+- Create a plain textfile with the contents of the SQLite database with the SQLite dump function
+
+Choose the method that fits you best.
+
+## Exporting from the UI
+
+The least technical option is to use the bookmark export in the UI.
+Go to the settings page and open the *Data* tab. 
+Then click on the *Download* button to download an HTML file containing all your bookmarks.
+Then backup this file on a drive, or an online file host.
+
+## Using the SQLite backup function
+
+Requires [SQLite](https://www.sqlite.org/index.html) to be installed on your host system.
+
+With this method you create a new SQLite database, which is a copy of your linkding database.
+This method uses the backup command in the [Command Line Shell For SQLite](https://sqlite.org/cli.html).
+```shell
+sqlite3 db.sqlite3 ".backup 'backup.sqlite3'"
+```
+After you have created the backup database `backup.sqlite` you have to move it to another system, for example with rsync.
+
+## Using the SQLite dump function
+
+Requires [SQLite](https://www.sqlite.org/index.html) to be installed on your host system.
+
+With this method you create a plain text file with the SQL statements to recreate the SQLite database.
+
+```shell
+sqlite3 db.sqlite3 .dump > backup.sql
+```
+
+As this is a plain text file you can commit it to any revision management system, like git.
+Using git you can commit the changes, followed by a git push to a remote repository.
+
+