Simple SSH user for read-only access to MySQL. Note, they still have a home directory and full SSH access so this assumes you trust them and/or need them to have access to other system features.

read_only_mysql_user.sh

# Create the SSH/system user
useradd dbreports
mkdir -p /home/dbreports/.ssh
chown -R dbreports:dbreports /home/dbreports/
chmod 700 /home/dbreports/.ssh

# Add the SSH keys
vim /home/dbreports/.ssh/authorized_keys
chmod 644 .ssh/authorized_keys 

# Add this user to 
mysql
> GRANT SELECT ON *.* TO 'dbreports'@'localhost' IDENTIFIED BY 'passwordhere';
> flush privileges;
> quit;

# You might want to replace `localhost` with `%` depending on access

# Test it out
mysql -u dbreports -p

Setup MySQL on Ubuntu