Make .cookie file readable for bitcoin group

Hey everyone,

happy to post my first question in THE bitcoin forum.

Problem
I just installed Bitcoin Core 22.0 on a Raspberry Pi4. As far as I understand it, the preferred authentication method for rpc calls should be via the .cookie file. Since I want to compartmentalize all software on the node I would have thought that the correct procedure is to create a dedicated group (say btcCookie) with read access to the .cookie file and then add the different users that need access to that group (I'm thinking of generic users like for an indexer). To create a dedicated group I changed the systemd bitcoin.service file to

Code:

[Service]
# Run as bitcoin:btcCookie
User=bitcoin
Group=btcCookie

This gave me indeed a dedicated group for the .cookie, bitcoind.pid and settings.json file. I'm not sure if it's a problem to have the pid and json file on the same group?!

Code:

bitcoin@debian:~/.bitcoin $ ll
total 183364
drwxrwx--- 5 bitcoin bitcoin 4096 Jun 22 14:32 .
drwxr-xr-x 3 root root 4096 Mar 13 17:26 ..
drwx------ 3 bitcoin bitcoin 176128 Jun 22 06:20 blocks
drwx------ 2 bitcoin bitcoin 106496 Jun 22 14:37 chainstate
drwx------ 3 bitcoin bitcoin 4096 Apr 1 17:28 indexes
-rw------- 1 bitcoin btcCookie 75 Jun 22 14:32 .cookie
-rw------- 1 bitcoin bitcoin 0 Apr 1 17:28 .lock
-rw------- 1 bitcoin bitcoin 34 Apr 1 17:28 banlist.json
-rw-r--r-- 1 bitcoin bitcoin 5480 Jun 22 14:17 bitcoin.conf
-rw------- 1 bitcoin btcCookie 6 Jun 22 14:32 bitcoind.pid
-rw------- 1 bitcoin bitcoin 184060873 Jun 22 14:37 debug.log
-rw------- 1 bitcoin bitcoin 247985 Jun 22 14:27 fee_estimates.dat
-rw------- 1 bitcoin bitcoin 1799583 Jun 22 14:27 mempool.dat
-rw------- 1 bitcoin bitcoin 1282929 Jun 22 14:27 peers.dat
-rw-r--r-- 1 bitcoin btcCookie 7 Jun 22 14:32 settings.json

Anyways, now I need to get the .cookie file in a readable state for the btcCookie group like so:

Code:

bitcoin@debian:~/.bitcoin $ ll
...
-rw-r----- 1 bitcoin btcCookie 75 Jun 22 14:32 .cookie
....

I've found someone with the same question https://www.reddit.com/r/Bitcoin/comments/9y1rtn/correct_way_to_use_cookie_auth_on_server/ but I'm not sure if his process is advisable and his outcome isn't problematic (in the process he also made mempool.dat and peers.dat group readable).

Another discussion re:permissions can be found here: https://bitcointalk.org/index.php?topic=5160894.0

Questions
1. How can I make the .cookie file group readable?
2. Is it problematic to have either or all of the following as group readable (bitcoind.pid, settings.json, mempool.dat and peers.dat)?
3. How can I prevent them from becoming group readable if so?
4. If no1 isn't possible, how can I provide other users with read access to the .cookie file?

Thank you and glad to be here!

Cheers,

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