From e17a5f7cdb418428218d27811355b1aba996c433 Mon Sep 17 00:00:00 2001
From: Gunwant Jain <mail@wantguns.dev>
Date: Tue, 18 Jan 2022 10:03:04 +0530
Subject: [PATCH] Docker, Cargo: Add multi-arch builds for arm64, x86_64 Builds
 static binaries instead to be runnable from scratch. This eases the build
 process, as we don't have to depend on docker's buildx. Now images for both
 arm64 and x86_64 can be built on x86_64 platform alone.

Signed-off-by: Gunwant Jain <mail@wantguns.dev>
---
 .cargo/config.toml |  7 +++++++
 Dockerfile         | 28 +++++++++++++++++++++++-----
 2 files changed, 30 insertions(+), 5 deletions(-)
 create mode 100644 .cargo/config.toml

diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 0000000..e319428
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,7 @@
+[build]
+target = "x86_64-unknown-linux-gnu"
+rustflags = ["-C", "target-feature=+crt-static"]
+
+[target.aarch64-unknown-linux-gnu]
+linker = "aarch64-linux-gnu-gcc"
+rustflags = ["-C", "target-feature=+crt-static"]
diff --git a/Dockerfile b/Dockerfile
index 242e42a..19cee2a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,12 +1,30 @@
-FROM rust:1 as builder
+###### Builder Image
+FROM rust as builder
 WORKDIR /app
 COPY . .
-RUN RUSTFLAGS='-C target-feature=+crt-static' cargo install --target x86_64-unknown-linux-gnu --path .
+# scratch does not have the mkdir binary, so we create a folder here
+RUN mkdir -p empty_upload
+
+ARG ARCH
+RUN __ARCH="$(dpkg --print-architecture)"; \
+    [ -z  $ARCH ] || __ARCH=$ARCH; \
+    case "$__ARCH" in \
+        arm64) \
+            export __TARGET='aarch64-unknown-linux-gnu'; \
+            apt update && apt upgrade -y; \
+            apt install -y gcc-aarch64-linux-gnu; \
+            rustup target add aarch64-unknown-linux-gnu; \
+            ;; \
+        amd64) export __TARGET='x86_64-unknown-linux-gnu' ;; \
+    esac; \
+    cargo install --target $__TARGET --path .;
+
 RUN cargo clean
 
-FROM debian:buster-slim as runner
-WORKDIR /app
-RUN mkdir -p upload
+
+###### Runner Image
+FROM scratch as runner
+COPY --from=builder /app/empty_upload upload
 COPY ./client upload/client
 COPY ./templates templates
 COPY ./static static