Comment 1 for bug 1328296

It is not possible to change --defaults-file with --defaults-extra-file. Although the two options seem to achieve the same result, there is a substantial difference.

When you use --defaults-file, the sandbox ignores any options file in the defaults locations:
/etc/my.cnf
/etc/mysql/my.cnf
$BASEDIR/my.cnf

If we use --defaults-extra-file, the above files are read before the given file. If they contain options that are not overwritten by the sandbox options file, strange things will happen.

When I designed the "my" script, I came across the inconsistent behavior when using multiple --defaults*-file options, and I decided that --defaults-file is the safest choice. I think this is more a bug in mysql tools than MySQL Sandbox.

Right now, if you add --defaults-extra-file to 'my', it passes it to the upstream tool:

./my sqldump --defaults-extra-file=./mysqldump.cnf --no-data mysql user
$HOME/opt/mysql/5.7.4/bin/mysqldump --defaults-file=$HOME/sandboxes/msb_5_7_4/my.sandbox.cnf --defaults-extra-file=./mysqldump.cnf --no-data mysql user

Here it is mysqldump that is not using the extra file.

I am open to suggestions that won't break the sandbox integrity