Add support for multi platform image

Author: adarshagrawal38

Dockerfile

@@ -5,9 +5,11 @@ ARG BASE_IMAGE=gcr.io/distroless/static:nonroot
 
 ## Multistage build
 FROM ${BUILDER_IMAGE} AS builder
+ARG TARGETOS
+ARG TARGETARCH
 ENV CGO_ENABLED=0
-ENV GOOS=linux
-ENV GOARCH=amd64
+ENV GOOS=$TARGETOS
+ENV GOARCH=$TARGETARCH
 ARG COMMIT_SHA=unknown
 ARG BUILD_REF
 

Makefile

@@ -23,7 +23,7 @@ SHELL = /usr/bin/env bash -o pipefail
 
 GIT_COMMIT_SHA ?= "$(shell git rev-parse HEAD 2>/dev/null)"
 GIT_TAG ?= $(shell git describe --tags --dirty --always)
-PLATFORMS ?= linux/amd64
+PLATFORMS ?= linux/amd64,linux/arm64
 DOCKER_BUILDX_CMD ?= docker buildx
 IMAGE_BUILD_CMD ?= $(DOCKER_BUILDX_CMD) build
 IMAGE_BUILD_EXTRA_OPTS ?=