Since upgrading to Ubuntu LTS 20.04 (from LTS 18), I've been bumped to the newer version of MySQL (from v5.7.3 to 8.0.16). All databases and configurations have been updated successfully, but the MySQL2 gem insists on trying to build against an older version of libmysqlclient (libmysqlclient.so.20 rather than the newer libmysqlclient.so.21)
I've uninstalled and reinstalled the APT packages: mysql-server and libmysqlclient-dev, as well as uninstalling and reinstalling the MySQL2 gem, but with no effect.
As you can see from the data below, it still appears to be incorrectly linking and I can't find a way to make it link to the correct version. Any help much appreciated.
$ gem list mysql2
*** LOCAL GEMS ***
mysql2 (0.5.3)
$ mysql -v -u *** -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 14
Server version: 8.0.21-0ubuntu0.20.04.4 (Ubuntu)
$ RAILS_ENV=production bundle exec rails c
Traceback (most recent call last):
1: from /home/**/**/shared/bundle/ruby/2.6.0/gems/mysql2-0.5.3/lib/mysql2.rb:36:in `<top (required)>'
/home/rails/kwai/shared/bundle/ruby/2.6.0/gems/mysql2-0.5.3/lib/mysql2.rb:36:in `require': libmysqlclient.so.20: cannot open shared object file: No such file or directory - /home/rails/kwai/shared/bundle/ruby/2.6.0/gems/mysql2-0.5.3/lib/mysql2/mysql2.so (LoadError)
$ ldd mysql2.so
linux-vdso.so.1 (0x00007fffa3b5e000)
libruby.so.2.6 => /home/***/.rvm/rubies/ruby-2.6.3/lib/libruby.so.2.6 (0x00007f8d4c92d000)
libmysqlclient.so.20 => not found
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f8d4c902000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f8d4c710000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f8d4c6f4000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f8d4c6e9000)
libgmp.so.10 => /usr/lib/x86_64-linux-gnu/libgmp.so.10 (0x00007f8d4c663000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f8d4c65d000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007f8d4c622000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f8d4c4d3000)
/lib64/ld-linux-x86-64.so.2 (0x00007f8d4cecc000)
$ ls -l /usr/lib/x86_64-linux-gnu/libmy*
-rw-r--r-- 1 root root 9242056 Aug 4 12:39 /usr/lib/x86_64-linux-gnu/libmysqlclient.a
lrwxrwxrwx 1 root root 20 Aug 4 12:39 /usr/lib/x86_64-linux-gnu/libmysqlclient.so -> libmysqlclient.so.21
lrwxrwxrwx 1 root root 25 Aug 4 12:39 /usr/lib/x86_64-linux-gnu/libmysqlclient.so.21 -> libmysqlclient.so.21.1.21
-rw-r--r-- 1 root root 7264264 Aug 4 12:39 /usr/lib/x86_64-linux-gnu/libmysqlclient.so.21.1.21
Finally solved it. I had to manually delete all previous copies of the gems in all builder and .rvm folders and then the gem seem to compile properly and everything worked again.