Migrate Confluence from Cloud to Server might be tricky because you need to reset the admin password in recovery mode. And the official doc doesn't work on a Cloudron instance. Here is how I made it.

Prerequisite:

Install cloudron cli npm install -g cloudron
Login to your cloudron cloudron login my.domain.com

Export data from Confluence Cloud and import data to Confluence Server:

In Confluence Cloud, go to Settings - Backup Manager - Create backup for server. Download the zip file.
Install Confluence app on Cloudron
Resize the app memory limit to 6GB (Strongly advise to avoid import failure)
Use web terminal to get database parameter: cat /app/data/credentials.txt
Open your Confluence, setup database connection, import the backup zip file.

After import succeed, you will need to login to Confluence, but the old password doesn't work. Follow these steps to reset admin password:

Enable debug mode of your app cloudron debug --app confluence.domain.com
Get a shell to your app's docker cloudron exec --app confluence.domain.com
Edit file vim /home/cloudron/confluence/bin/setenv.sh
Add CATALINA_OPTS="-Datlassian.recovery.password=your_random_password" to the end of file, after the last CATALINA_OPTS line. Save.
Start confluence by run /home/cloudron/start.sh
Login your confluence with username recovery_admin and the password in step 4.
The Confluence site seems empty and ask you to create a space. Don't worry, create a new space.
Open Settings - User Management, list all users. Find your old admin user, reset password and add it to all admin groups.
Logout, and try login with your admin user. It works!
Delete the the CATALINA_OPTS added in setenv.sh
Exit from app docker. Disable debug mode by running cloudron debug --disable --app configure.domain.com. Wait the app restart.
Your Confluence is ready!

Reference:

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