build(docker): reduce image size by ~10%

Switching from alpine to scratch as base image.

Dockerfile

@@ -1,5 +1,6 @@
 FROM golang:1.22 AS build
 
+RUN mkdir -p /etc/sablier/themes
 WORKDIR /src
 RUN go env -w GOMODCACHE=/root/.cache/go-build
 
@@ -18,11 +19,9 @@ ARG TARGETARCH
 RUN --mount=type=cache,target=/root/.cache/go-build \
     make BUILDTIME=${BUILDTIME} VERSION=${VERSION} GIT_REVISION=${REVISION} ${TARGETOS}/${TARGETARCH}
 
-FROM alpine:3.20.3
-
-RUN mkdir -p /etc/sablier/themes
-EXPOSE 10000
+FROM scratch
 
+COPY --from=build /etc/sablier/themes /etc/sablier/themes
 COPY --from=build /src/sablier* /bin/sablier
 COPY docker/sablier.yaml /etc/sablier/sablier.yaml
 

Makefile

@@ -39,7 +39,7 @@ test-plugin-caddy:
 
 .PHONY: docker
 docker:
-	docker build -t acouvreur/sablier:local .
+	docker build --build-arg BUILDTIME=$(BUILDTIME) --build-arg VERSION=$(VERSION) --build-arg REVISION=$(GIT_REVISION) -t acouvreur/sablier:local .
 
 caddy:
 	docker build -t caddy:local plugins/caddy