Apparently the amd64 emulation used when building a #Docker image on arm64 hardware is only so good. When installing #Ruby with rvm it decides to install the arm64 version anyway.

$ uname -a
Linux 628f228dda6f 4.14.22 #1 SMP Thu Oct 27 08:01:25 UTC 2022 Build-38 x86_64 GNU/Linux

$ file /home/diaspora/.rvm/rubies/ruby-2.7.8/bin/ruby
/home/diaspora/.rvm/rubies/ruby-2.7.8/bin/ruby: ELF 64-bit LSB pie executable, ARM aarch64, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-aarch64.so.1, for GNU/Linux 3.7.0, BuildID[sha1]=e3ea67d64604f36deef9f6eb95cc99078337d287, with debug_info, not stripped

So the new Diaspora Docker image will be up in a few minutes while I build it on some amd64 hardware I have lying around.