Set docker platform flag so core works on ARM Macs (stellar#4177)

integration.sh

@@ -12,7 +12,12 @@ export TRACY_NO_INVARIANT_CHECK=1 # This fails on my dev vm. - Paul
 # launch postgres if it's not already.
 if [[ "$(docker inspect integration_postgres -f '{{.State.Running}}')" != "true" ]]; then
   docker rm -f integration_postgres || true;
-  docker run -d --name integration_postgres --env POSTGRES_HOST_AUTH_METHOD=trust -p 5432:5432 circleci/postgres:9.6.5-alpine
+  docker run -d \
+    --name integration_postgres \
+    --platform linux/amd64 \
+    --env POSTGRES_HOST_AUTH_METHOD=trust \
+    -p 5432:5432 \
+    circleci/postgres:9.6.5-alpine
 fi
 
 exec go test -timeout 25m github.com/stellar/go/services/horizon/internal/integration/... "$@"

services/horizon/docker/docker-compose.integration-tests.yml

@@ -10,6 +10,7 @@ services:
       - "5641:5641"
     command: ["-p", "5641"]
   core:
+    platform: linux/amd64
     # TODO replace with official SDF image when ready. Note that this:
     # https://github.com/stellar/stellar-core/commit/31597b760f8e325fc84da0937adc373a78878ca9
     # breaks the tests. I reverted it before building temp docker image.

services/horizon/docker/docker-compose.pubnet.yml

@@ -1,9 +1,10 @@
 version: '3'
 services:
   horizon:
+    platform: linux/amd64
     environment:
       - HISTORY_ARCHIVE_URLS=https://history.stellar.org/prd/core-live/core_live_001
       - NETWORK_PASSPHRASE=Public Global Stellar Network ; September 2015
       - CAPTIVE_CORE_CONFIG_APPEND_PATH=/captive-core-pubnet.cfg
     volumes:
-      - ./captive-core-pubnet.cfg:/captive-core-pubnet.cfg
+      - ./captive-core-pubnet.cfg:/captive-core-pubnet.cfg

services/horizon/docker/docker-compose.standalone.yml

@@ -13,6 +13,7 @@ services:
       - "core-db-data:/var/lib/postgresql/data"
 
   core:
+    platform: linux/amd64
     image: ${CORE_IMAGE:-stellar/stellar-core:18}
     depends_on:
       - core-postgres

services/horizon/docker/docker-compose.yml

@@ -12,6 +12,7 @@ services:
       - "horizon-db-data:/var/lib/postgresql/data"
 
   horizon:
+    platform: linux/amd64
     depends_on:
       - horizon-postgres
     build: