Multistage Docker build

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"]

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 \
+  .