`make docker-start` fails on an M1/arm64 Macbook PRO

[davidalpert]

I recently cloned this repo on a new M1 MacBook with arm64 architecture and ran into the following Docker error when running make docker-start:

❯ make docker-start
GDBL_DATA_DIR= GDBL_LOG_LEVEL= GDBL_VERSION=latest docker-compose up
Creating network "godbledger-web_default" with the default driver
Pulling db (mysql:8)...
8: Pulling from library/mysql
ERROR: no matching manifest for linux/arm64/v8 in the manifest list entries
make: *** [docker-start] Error 1

I have seen this kind of error many times since adopting this M1/arm64 MacBook. In many cases, vendors have not yet published ARM-compatible images of their products.

As a workaround, I propose that we:

1. add explicit --platform linux/amd64 to the FROM commands in utils/Dockerfile.build-web; and
2. add an explicit DOCKER_DEFAULT_PLATFORM=linux/amd64 hint to the docker-start make target

The first point should ensure that the docker-build target builds an AMD-compatible godbledger-web image that can run under the same amd64 platform which the mysql seems to assume.

The second tells docker-compose to override the local platform defaults and start up the db, godbledger server, and godbledger-web apps all in amd64 mode.