* Add override file for ARM64 setups.
This commit adds an override file which explicitly specifies the container platform to be linux/amd64.
It forces docker to pull/build/run the amd64 image (even on arm64 hosts).
Assuming binfmt support is set up, this will run the amd64 applications via emulation.
* Add arm64 override file information to README.
Adds a section covering the experimental setup for
arm64 hosts to the README.
* Make the ARM64 override survive the next compose command (#1900)
The override only applies while both -f flags are on the command line, and
every other instruction in this README is written bare. An ARM64 user who
followed the update steps would drop the platform pin without noticing: a
manifest error today, and a silent switch off emulation once native ARM64
images ship. The quick start now writes COMPOSE_FILE into .env, so the rest
of the file works unchanged on ARM64 -- verified both ways, with and without
that line.
Two things the setup needs stated where it is read rather than one hop away
in the wiki: binfmt has to be registered on the host or the container dies
with "exec format error", and emulation costs roughly 3-6x native slice
time. Both now lead the section, and the separate-x86_64-box route stays the
recommendation it was -- emulation is the fallback for people who have no
second machine, not a replacement.
The compose file's own header said ARM64 was a dead end. It now points at
the override, for anyone who reads the stack instead of the README.
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Co-authored-by: MartinNYHC <martin@bambuddy.cool>
Co-authored-by: maziggy <mz@v8w.de>
