From f28c8bc1c2b84d54068f0218a9b1f64b83cf6576 Mon Sep 17 00:00:00 2001
From: cimnine <mail@cimnine.ch>
Date: Mon, 20 Sep 2021 14:18:48 +0200
Subject: [PATCH] Multistage Docker build

---
 .dockerignore     | 12 ++++++++++++
 docker/Dockerfile | 15 +++++++++++++--
 docker/build.sh   | 12 +++++++-----
 3 files changed, 32 insertions(+), 7 deletions(-)
 create mode 100644 .dockerignore

diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 000000000..2e1b785e0
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,12 @@
+# Folders
+.git/
+.github/
+changelog/
+doc/
+docker/
+helpers/
+
+# Files
+.gitignore
+.golangci.yml
+*.md
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 3268f987b..dacb02542 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,7 +1,18 @@
-FROM alpine:latest
+FROM golang:1.16-alpine AS builder
 
-COPY restic /usr/bin
+WORKDIR /go/src/github.com/restic/restic
+
+# Caching dependencies
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN go run build.go
+
+FROM alpine:latest AS restic
 
 RUN apk add --update --no-cache ca-certificates fuse openssh-client tzdata
 
+COPY --from=builder /go/src/github.com/restic/restic/restic /usr/bin
+
 ENTRYPOINT ["/usr/bin/restic"]
diff --git a/docker/build.sh b/docker/build.sh
index 729b837e8..bd4477951 100755
--- a/docker/build.sh
+++ b/docker/build.sh
@@ -2,10 +2,12 @@
 
 set -e
 
-echo "Build binary using golang docker image"
-docker run --rm -ti \
-    -v "`pwd`":/go/src/github.com/restic/restic \
-    -w /go/src/github.com/restic/restic golang:1.16-alpine go run build.go
+export DOCKER_BUILDKIT=${DOCKER_BUILDKIT-1}
 
 echo "Build docker image restic/restic:latest"
-docker build --rm -t restic/restic:latest -f docker/Dockerfile .
+docker build \
+  --rm \
+  --pull \
+  --file docker/Dockerfile \
+  --tag restic/restic:latest \
+  .