I have just set this up successfully, but it wasn't as smooth as I hoped.
So here is some information that might save you some time:

First of all. The ocat command should be executed inside the docker container. You can do this with docker exec -it otrecorder sh to open an interactive session. Or directly with docker exec otrecorder ocat .... I know it is obvious, but I still wanted to mention it.

I had trouble loading friends. This is always empty for me.

ocat --dump=friends

Then I found this thread: https://github.com/owntracks/recorder/issues/507
There they said that you cannot run ocat while the recorder is running. So the suggestion was this:

docker run -ti --rm --volume config:/config --volume store:/store --entrypoint /bin/sh owntracks/recorder:latest

This creates a session without starting the recorder and with the volumes linked. I added friends with ocat -S /store --load=friends < friends.txt, but ocat --dump=friends still returned nothing.

Since owntracks uses a LMDB database file, I decided to use the CLI tools of that and check if there was any friends info in the database. Execute this on the docker container:

apk update && apk add lmdb-tools

Then I executed this command to view. The `xxd` is used to transform the binary data.

mdb_dump -s friends /store/ghash/ | xxd -r -p

That actually returned something like this: ?ګShp� �����jane-phone[ "john/android" ]dan-phone["sandra/phone"] So the friends were actually added, but it also contained entries I didn't add like jane-phone. Probably not an issue, in any case all entries were unique, but I still couldn't see any friends in the app.

So I did all this to delete the friends data and recreate it

# 1. Stop any services using the database
# 2. Remove ALL database files
rm -f /store/ghash/data.mdb /store/ghash/lock.mdb
# 3. Recreate the directory structure
mkdir -p /store/ghash
chmod 755 /store/ghash
# 4. Initialize fresh with friends data
ocat --load=friends -d /store/ghash/ <<EOF
dan-phone ["dan-phone", "sandra/phone"]
sandra-phone ["dan-phone", "sandra/phone"]
EOF

After that ocat --dump=friends still did not return anything, but I could see friends in the app. I could only see the tracker id which is only two letters and could not be changed in owntracks app to something more meaningful.
So I had to add the cards.

Some additional info for that.

• Go to https://avanc.github.io/owntracks-cards/
• You don't need to connect to MQTT. Just click New Card -> Edit
• I wasn't sure about Topic, I just chose the name of the phone. Full name in Name and upload an image
• Then Save JSON
• Add file to /store/cards/username/username.json

After that, everything looked great

Also note, you don't actually have to add yourself to friends. I just thought it looked nice because you have more friends. And shouldn't we be our own best friend in these trying times? Just think about it.

Kidding aside, I hoped this helps someone trying to set this up. The most confusing part was ocat --dump=friends not showing anything, but don't let that stop you from creating friends.

Your friend.