🐛 Declaring BUILDPLATFORM before usage on Dockerfile + default substitution

.cloudbuild/dev.yaml

@@ -7,6 +7,8 @@ steps:
       - CLOUDSDK_CORE_PROJECT=globekeeper-development
       - CLOUDSDK_COMPUTE_ZONE=europe-west2-a
       - CLOUDSDK_CONTAINER_CLUSTER=synapse
+substitutions:
+  _BUILD_PLATFORM: linux/amd64 # default
 images:
   - gcr.io/$PROJECT_ID/dendrite-monolith:$COMMIT_SHA
 timeout: 480s

Dockerfile

@@ -1,6 +1,7 @@
 #
 # base installs required dependencies and runs go mod download to cache dependencies
 #
+ARG BUILDPLATFORM=${BUILDPLATFORM}
 FROM --platform=${BUILDPLATFORM} docker.io/golang:1.20-alpine AS base
 RUN apk --update --no-cache add bash build-base curl