(docker) enable cross platform build using docker buildx (\#9073) (#9074)

CHANGELOG_PENDING.md

@@ -30,3 +30,5 @@ Friendly reminder, we have a [bug bounty program](https://hackerone.com/tendermi
 - [abci] \#5706 Added `AbciVersion` to `RequestInfo` allowing applications to check ABCI version when connecting to Tendermint. (@marbar3778)
 
 ### BUG FIXES
+
+[docker] \#9073 enable cross platform build using docker buildx

DOCKER/Dockerfile

@@ -1,11 +1,11 @@
 # stage 1 Generate Tendermint Binary
-FROM golang:1.15-alpine as builder
+FROM --platform=$BUILDPLATFORM golang:1.15-alpine as builder
 RUN apk update && \
     apk upgrade && \
     apk --no-cache add make
 COPY / /tendermint
 WORKDIR /tendermint
-RUN make build-linux
+RUN TARGETPLATFORM=$TARGETPLATFORM make build-linux
 
 # stage 2
 FROM golang:1.15-alpine

Makefile

@@ -53,6 +53,67 @@ endif
 # allow users to pass additional flags via the conventional LDFLAGS variable
 LD_FLAGS += $(LDFLAGS)
 
+# Process Docker environment varible TARGETPLATFORM 
+# in order to build binary with correspondent ARCH
+# by default will always build for linux/amd64
+TARGETPLATFORM ?= 
+GOOS ?= linux
+GOARCH ?= amd64
+GOARM ?=
+
+ifeq (linux/arm,$(findstring linux/arm,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=arm
+	GOARM=7
+endif
+
+ifeq (linux/arm/v6,$(findstring linux/arm/v6,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=arm
+	GOARM=6
+endif
+
+ifeq (linux/arm64,$(findstring linux/arm64,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=arm64
+	GOARM=7
+endif
+
+ifeq (linux/386,$(findstring linux/386,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=386
+endif
+
+ifeq (linux/amd64,$(findstring linux/amd64,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=amd64
+endif
+
+ifeq (linux/mips,$(findstring linux/mips,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=mips
+endif
+
+ifeq (linux/mipsle,$(findstring linux/mipsle,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=mipsle
+endif
+
+ifeq (linux/mips64,$(findstring linux/mips64,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=mips64
+endif
+
+ifeq (linux/mips64le,$(findstring linux/mips64le,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=mips64le
+endif
+
+ifeq (linux/riscv64,$(findstring linux/riscv64,$(TARGETPLATFORM)))
+	GOOS=linux
+	GOARCH=riscv64
+endif
+
 all: check build test install
 .PHONY: all
 
@@ -244,7 +305,7 @@ build-docker: build-linux
 
 # Build linux binary on other platforms
 build-linux:
-	GOOS=linux GOARCH=amd64 $(MAKE) build
+	GOOS=$(GOOS) GOARCH=$(GOARCH) GOARM=$(GOARM) $(MAKE) build
 .PHONY: build-linux
 
 build-docker-localnode: