Redmine

Hi, we also use Redmine from Docker, for this we use the version from Sameersbn: https://github.com/sameersbn/docker-redmine

Extensive parameterization is possible here, e.g. information about an external database, paths for files, templates and SSL certificates...

Thanks. We've tried several docker versions; however, the issue isn't getting redmine to work (we have that already), but with getting our old data into the new Redmine instance. We import the data into the database but no projects are showing up in Redmine.

After using Redmine for several years, we are about at the point of leaving because we can't find any solution (and importing data really shouldn't be this hard).
(And frustrating that most instructions are years old)

BTW ... we did try the sameersbn docker image but could never get it to run (in the Plesk docker setup .... it didn't include any DB variables, and even when adding them ourselves, we couldn't get it to initiate a connection to MySQL.

If the database was copied correctly from the old installation, the data should be available in the new Redmine version even if the migration is correct. The migration instructions are up to date and working: RedmineUpgrade.
It is important to understand the path to the database - without correct parameterization, a database integrated in the Docker environment is created that is difficult to access from the outside - an external database cannot, understandably, be accessed via local paths such as "localhost" or "127.0.01 " address...
At Sameersbn, all possible parameters are listed on the Github page

Thanks. But I think you're still missing the process we are following. We are not 'upgrading' Redmine. We are trying to 'migrate' the data from on 4.1.1 version (on Server A) to another instance running version 5.0.5 (on Server B).
The link you included was on how to upgrade, not migrate.

And, as I've mentioned, we can see the data in the new database that is used by our instance of the 'official' redmine package (installed via Docker Extension in Plesk). But the Sameersbn redmine package doesn't have a db included and exposes no environment variables (for the plesk docker instance) related to the db, and manually adding them within the docker settings doesn't allow that instance to connect to the db provided in the system. (Based on the information provided in their github).

The closest 'instructions' that we could find are very old (0.9.3 to 1.1.2 - https://www.redmine.org/projects/redmine/wiki/HowTo_Migrate_Redmine_to_a_new_server_to_a_new_Redmine_version). And I've not found any other discussion on how to migrate Redmine from one server to another. So I'm just guessing that there is no 'official' way to do this.

You want to switch from version 4.x to version 5.x - this is an upgrade (The installation destination is irrelevant)! So please take your time and read the instructions carefully. Basically, the data from the old system must be backed up and migrated to the new system (this is described in the instructions from step 3).
If the Docker image cannot establish a connection to the external database, the variable information is simply incorrect - We use Redmine via Docker on a Synology NAS - their package manager looks very similar to Plesk's, so the following variables should be used:
DB_HOST : Physical IP or hostname to the database server (localhost or 127.0.0.1 will not work!)
DB_PORT : The database server port. Defaults to 3306
DB_NAME : The database name. Defaults to redmine_production
DB_USER : The database user. Defaults to root
DB_PASS : The database password. Defaults to no password
DB_ADAPTER : The database type. Possible values: mysql2, postgresql, and 'sqlite3'. Defaults to mysql.
DB_ENCODING : The database encoding. For DB_ADAPTER values postresql and mysql2, this parameter defaults to unicode and utf8 respectively.

Thanks for the info, I will keep it in my mind.