Running MySQL with on different directory - mysql

Question

GOAL:
I am trying to run mysql on my work servers machines. But as admins did not install it in the usual default installation path, it fails. How can I make it works?
FACTS:
MySQL is installed under: /opt/mysql/10.1.16/
$> ls -1 /opt/mysql/10.1.16/
bin
COPYING
COPYING.LESSER
COPYING.thirdparty
CREDITS
data
EXCEPTIONS-CLIENT
include
INSTALL-BINARY
lib
man
mysql-test
README
README-wsrep
scripts
share
sql-bench
support-files
However, when I want to run mysql from a script, I do:
export LIBMYSQL_PLUGIN_DIR="/opt/mysql/10.1.16/lib/plugin"
export LD_LIBRARY_PATH="/opt/mysql/10.1.16/lib"
export LD_RUN_PATH="/opt/mysql/10.1.16/lib"
export PATH="/opt/mysql/10.1.16/bin:/home/xxxxxxxx/bin:/usr/local/bin:/usr/bin:/bin:/usr/lib64/jvm/jre/bin:/usr/lib/mit/bin:/usr/lib/mit/sbin"
/opt/mysql/10.1.16/bin/mysql -C --no-beep --line-numbers --protocol=TCP --host="${DB_HOSTNAME}" --port="${DB_PORT}" --user="${DB_USER}" --database "${DB_SCHEMA}" -o --delimiter ','
With all my DB_xxxx corectly set, I get the following error:
ERROR 2059 (HY000): Authentication plugin 'dialog' cannot be loaded: /usr/local/mysql/lib/plugin/dialog.so: cannot open shared object file: No such file or directory
I checked the official documentation page:
https://dev.mysql.com/doc/refman/8.0/en/environment-variables.html and the only mention about plugin is to check if LIBMYSQL_PLUGIN_DIR, which seems good since:
$> echo "${LIBMYSQL_PLUGIN_DIR}"
/opt/mysql/10.1.16/lib/plugin
$> ls -la /opt/mysql/10.1.16/lib/plugin
-rwxr-xr-x 1 mysql dba 17382 Sep 13 2016 adt_null.so
-rwxr-xr-x 1 mysql dba 12462 Sep 13 2016 auth_0x0100.so
-rwxr-xr-x 1 mysql dba 33039 Sep 13 2016 auth_gssapi_client.so
-rwxr-xr-x 1 mysql dba 80774 Sep 13 2016 auth_gssapi.so
-rwxr-xr-x 1 mysql dba 18007 Sep 13 2016 auth_pam.so
-rwxr-xr-x 1 mysql dba 13028 Sep 13 2016 auth_socket.so
-rwxr-xr-x 1 mysql dba 23521 Sep 13 2016 auth_test_plugin.so
-rw-r--r-- 1 mysql dba 227 Sep 13 2016 daemon_example.ini
-rwxr-xr-x 1 mysql dba 15267 Sep 13 2016 debug_key_management.so
-rwxr-xr-x 1 mysql dba 14975 Sep 13 2016 dialog_examples.so
-rwxr-xr-x 1 mysql dba 39102 Sep 13 2016 dialog.so
-rwxr-xr-x 1 mysql dba 35337 Sep 13 2016 example_key_management.so
-rwxr-xr-x 1 mysql dba 67516 Sep 13 2016 file_key_management.so
-rwxr-xr-x 1 mysql dba 534847 Sep 13 2016 ha_archive.so
-rwxr-xr-x 1 mysql dba 326244 Sep 13 2016 ha_blackhole.so
-rwxr-xr-x 1 mysql dba 6315641 Sep 13 2016 ha_connect.so
-rwxr-xr-x 1 mysql dba 270829 Sep 13 2016 ha_example.so
-rwxr-xr-x 1 mysql dba 408688 Sep 13 2016 ha_federated.so
-rwxr-xr-x 1 mysql dba 658050 Sep 13 2016 ha_federatedx.so
-rwxr-xr-x 1 mysql dba 17067973 Sep 13 2016 ha_innodb.so
-rwxr-xr-x 1 mysql dba 13007344 Sep 13 2016 ha_mroonga.so
-rwxr-xr-x 1 mysql dba 1586135 Sep 13 2016 handlersocket.so
-rwxr-xr-x 1 mysql dba 1687004 Sep 13 2016 ha_oqgraph.so
-rwxr-xr-x 1 mysql dba 745005 Sep 13 2016 ha_sphinx.so
-rwxr-xr-x 1 mysql dba 5150095 Sep 13 2016 ha_spider.so
-rwxr-xr-x 1 mysql dba 226800 Sep 13 2016 ha_test_sql_discovery.so
-rwxr-xr-x 1 mysql dba 35898 Sep 13 2016 libdaemon_example.so
-rwxr-xr-x 1 mysql dba 131020 Sep 13 2016 locales.so
-rwxr-xr-x 1 mysql dba 221483 Sep 13 2016 metadata_lock_info.so
-rwxr-xr-x 1 mysql dba 18211 Sep 13 2016 mypluglib.so
-rwxr-xr-x 1 mysql dba 16382 Sep 13 2016 mysql_clear_password.so
-rwxr-xr-x 1 mysql dba 18751 Sep 13 2016 qa_auth_client.so
-rwxr-xr-x 1 mysql dba 24478 Sep 13 2016 qa_auth_interface.so
-rwxr-xr-x 1 mysql dba 13542 Sep 13 2016 qa_auth_server.so
-rwxr-xr-x 1 mysql dba 229059 Sep 13 2016 query_cache_info.so
-rwxr-xr-x 1 mysql dba 286720 Sep 13 2016 query_response_time.so
-rwxr-xr-x 1 mysql dba 534415 Sep 13 2016 semisync_master.so
-rwxr-xr-x 1 mysql dba 445144 Sep 13 2016 semisync_slave.so
-rwxr-xr-x 1 mysql dba 175928 Sep 13 2016 server_audit.so
-rwxr-xr-x 1 mysql dba 32295 Sep 13 2016 simple_password_check.so
-rwxr-xr-x 1 mysql dba 19846 Sep 13 2016 sql_errlog.so
-rwxr-xr-x 1 mysql dba 218688 Sep 13 2016 wsrep_info.so
All libraries have execution rights, they are all here BUT MYSQL is still trying to search in the default path /usr/local/mysql/lib/plugin/. And of course on our machine, this path does not exist.
QUESTION:
Is there another option/way to specifically ask mysql to load plugin for a specific directory?
NOTES:
I found some links about the error ERROR 2059 (HY000): Authentication plugin 'dialog' cannot be loaded: /usr/local/mysql/lib/plugin/dialog.so: cannot open shared object file: No such file or directory but solutions are all:
Uninstall mysql and install it again (which I can't)
Create the directory or symlink (I can't neither)
Use the --enable-cleartext-plugin option (it does nothing and I don't think it is related in my case)

Answer 1

So I think I understood why.
Setting LIBMYSQL_PLUGIN_DIR:
export LIBMYSQL_PLUGIN_DIR="/opt/mysql/10.1.16/lib/plugin"
is somehow not read or taken in account.
However, adding directly to the binary the option --plugin-dir="${LIBMYSQL_PLUGIN_DIR}" will make it work.
So correct answer is:
/opt/mysql/10.1.16/bin/mysql --plugin-dir="${LIBMYSQL_PLUGIN_DIR}" -C --no-beep --line-numbers --protocol=TCP --host="${DB_HOSTNAME}" --port="${DB_PORT}" --user="${DB_USER}" --database "${DB_SCHEMA}" -o --delimiter ','
Why the env varibale is not read, that is a mystery