From 2ce93b6b31f8a3dc47bdacaf5e6d4e0b960d1974 Mon Sep 17 00:00:00 2001
From: Joel  Speed <joel.speed@hotmail.co.uk>
Date: Tue, 5 Oct 2021 16:58:54 +0100
Subject: [PATCH] Improve build times by sharing cache and allowing platform
 selection

---
 CHANGELOG.md |  1 +
 Dockerfile   | 22 +++++++++++++++++++---
 Makefile     | 12 +++++++-----
 3 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d36a0dbc..e350bf2b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@
 
 ## Changes since v7.1.3
 
+- [#1391](https://github.com/oauth2-proxy/oauth2-proxy/pull/1391) Improve build times by sharing cache and allowing platform selection (@JoelSpeed)
 - [#1404](https://github.com/oauth2-proxy/oauth2-proxy/pull/1404) Improve error message when no cookie is found (@JoelSpeed)
 - [#1315](https://github.com/oauth2-proxy/oauth2-proxy/pull/1315) linkedin: Update provider to v2 (@wuurrd)
 - [#1348](https://github.com/oauth2-proxy/oauth2-proxy/pull/1348) Using the native httputil proxy code for websockets rather than yhat/wsutil to properly handle HTTP-level failures (@thetrime)
diff --git a/Dockerfile b/Dockerfile
index 321f5691..1ebe7a87 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,16 +1,24 @@
-FROM golang:1.16-buster AS builder
+# All builds should be done using the platform native to the build node to allow
+#  cache sharing of the go mod download step.
+# Go cross compilation is also faster than emulation the go compilation across
+#  multiple platforms.
+FROM --platform=${BUILDPLATFORM} golang:1.16-buster AS builder
 
 # Copy sources
 WORKDIR $GOPATH/src/github.com/oauth2-proxy/oauth2-proxy
 
 # Fetch dependencies
 COPY go.mod go.sum ./
-RUN GO111MODULE=on go mod download
+RUN go mod download
 
 # Now pull in our code
 COPY . .
 
+# Arguments go here so that the previous steps can be cached if no external
+#  sources have changed.
 ARG VERSION
+ARG TARGETPLATFORM
+ARG BUILDPLATFORM
 
 # Build binary and make sure there is at least an empty key file.
 #  This is useful for GCP App Engine custom runtime builds, because
@@ -18,7 +26,15 @@ ARG VERSION
 #  build the key into the container and then tell it where it is
 #  by setting OAUTH2_PROXY_JWT_KEY_FILE=/etc/ssl/private/jwt_signing_key.pem
 #  in app.yaml instead.
-RUN VERSION=${VERSION} make build && touch jwt_signing_key.pem
+# Set the cross compilation arguments based on the TARGETPLATFORM which is
+#  automatically set by the docker engine.
+RUN case ${TARGETPLATFORM} in \
+         "linux/amd64")  GOARCH=amd64  ;; \
+         "linux/arm64")  GOARCH=arm64  ;; \
+         "linux/arm/v6") GOARCH=arm GOARM=6  ;; \
+    esac && \
+    printf "Building OAuth2 Proxy for arch ${GOARCH}\n" && \
+    VERSION=${VERSION} make build && touch jwt_signing_key.pem
 
 # Copy binary to alpine
 FROM alpine:3.14
diff --git a/Makefile b/Makefile
index 414dc85f..d0368ebf 100644
--- a/Makefile
+++ b/Makefile
@@ -22,8 +22,8 @@ all: lint $(BINARY)
 
 .PHONY: clean
 clean:
-	rm -rf release
-	rm -f $(BINARY)
+	-rm -rf release
+	-rm -f $(BINARY)
 
 .PHONY: distclean
 distclean: clean
@@ -37,10 +37,12 @@ lint: validate-go-version
 build: validate-go-version clean $(BINARY)
 
 $(BINARY):
-	GO111MODULE=on CGO_ENABLED=0 $(GO) build -a -installsuffix cgo -ldflags="-X main.VERSION=${VERSION}" -o $@ github.com/oauth2-proxy/oauth2-proxy/v7
+	CGO_ENABLED=0 $(GO) build -a -installsuffix cgo -ldflags="-X main.VERSION=${VERSION}" -o $@ github.com/oauth2-proxy/oauth2-proxy/v7
 
+DOCKER_BUILD_PLATFORM ?= linux/amd64,linux/arm64,linux/arm/v6
+DOCKER_BUILDX_ARGS ?=
 DOCKER_BUILD := docker build --build-arg VERSION=${VERSION}
-DOCKER_BUILDX := docker buildx build --platform linux/amd64,linux/arm64,linux/arm/v6 --build-arg VERSION=${VERSION}
+DOCKER_BUILDX := docker buildx build ${DOCKER_BUILDX_ARGS} --platform ${DOCKER_BUILD_PLATFORM} --build-arg VERSION=${VERSION}
 
 .PHONY: docker
 docker:
@@ -58,7 +60,7 @@ docker-all: docker
 
 .PHONY: docker-push
 docker-push:
-	docker buildx build --push --platform linux/amd64,linux/arm64,linux/arm/v6 -t $(REGISTRY)/oauth2-proxy:latest .
+	docker buildx build --push --platform ${DOCKER_BUILD_PLATFORM} -t $(REGISTRY)/oauth2-proxy:latest .
 
 .PHONY: docker-push-all
 docker-push-all: docker-push