Support cross-building

- Specify --platform in the golang build stage
- Set GOOS and GOARCH env vars
- Set CGO_ENABLED=0 to build static binaries
- Remove apt-get upgrades; changed base image to chainguard/static

I don't think we need buildx?

Containerfile

@@ -1,6 +1,8 @@
 # Base image for build
 ARG base_image_version=1.20.7
-FROM golang:${base_image_version} as builder
+FROM --platform=$BUILDPLATFORM golang:${base_image_version} as builder
+ARG TARGETARCH
+ARG TARGETOS
 
 # Switch workdir
 WORKDIR /opt/apm-perf
@@ -9,12 +11,15 @@ WORKDIR /opt/apm-perf
 COPY . .
 
 # Build 
+ENV GOOS=$TARGETOS
+ENV GOARCH=$TARGETARCH
+ENV CGO_ENABLED=0
 RUN \
   go mod download \
   && make build
 
-# Base image for build
-FROM debian:bookworm
+# Base image for final image
+FROM cgr.dev/chainguard/static
 
 # Arguments
 ARG commit_sha
@@ -37,18 +42,6 @@ LABEL \
 # Switch workdir
 WORKDIR /opt/apm-perf
 
-# Add minimal stuff
-RUN \
-  apt-get update > /dev/null \
-  && apt-get upgrade -y \
-  && apt-get install -y --no-install-recommends \
-    "apt-utils=*" \
-    "ca-certificates=*" \
-    "curl=*" \
-    "gnupg=*" \
-  && apt-get clean \
-  && rm -rf /var/lib/apt/lists/*
-
 # Copy files for apmsoak
 COPY --from=builder /opt/apm-perf/dist/apmsoak /usr/bin/apmsoak
 COPY ./internal/loadgen/events ./events

Makefile

@@ -48,7 +48,7 @@ package: PROJECT_URL=$$(go list -m all | head -1)
 package:
 	mkdir -p $(STATES_DIR)
 	echo "$(IMAGE_REF)" > "$(STATES_DIR)/image_ref"
-	docker buildx build \
+	docker build \
 		--build-arg base_image_version=$(BASE_IMAGE_VERSION) \
 		--build-arg commit_sha=$(COMMIT_SHA) \
 		--build-arg current_time=$(CURRENT_TIME_ISO) \