Add mount cache for docker building

Author: lunny

Dockerfile

@@ -9,6 +9,12 @@ ARG TAGS="sqlite sqlite_unlock_notify"
 ENV TAGS="bindata timetzdata $TAGS"
 ARG CGO_EXTRA_CFLAGS
 
+ARG GOCACHE
+ENV GOCACHE=${GOCACHE:-/root/.cache/go-build}
+
+ARG GOMODCACHE
+ENV GOMODCACHE=${GOMODCACHE:-/go/pkg/mod}
+
 # Build deps
 RUN apk --no-cache add \
     build-base \
@@ -23,10 +29,17 @@ WORKDIR ${GOPATH}/src/code.gitea.io/gitea
 
 # Checkout version if set
 RUN if [ -n "${GITEA_VERSION}" ]; then git checkout "${GITEA_VERSION}"; fi \
- && make clean-all build
+  && make clean-all
+
+RUN --mount=type=cache,target=/root/.npm \
+  --mount=type=cache,target=/go/pkg/mod/ \
+  --mount=type=cache,target="/root/.cache/go-build" \
+  make build
 
 # Begin env-to-ini build
-RUN go build contrib/environment-to-ini/environment-to-ini.go
+RUN --mount=type=cache,target=/go/pkg/mod/ \
+  --mount=type=cache,target="/root/.cache/go-build" \
+  go build contrib/environment-to-ini/environment-to-ini.go
 
 # Copy local files
 COPY docker/root /tmp/local

Dockerfile.rootless

@@ -9,6 +9,12 @@ ARG TAGS="sqlite sqlite_unlock_notify"
 ENV TAGS="bindata timetzdata $TAGS"
 ARG CGO_EXTRA_CFLAGS
 
+ARG GOCACHE
+ENV GOCACHE=${GOCACHE:-/root/.cache/go-build}
+
+ARG GOMODCACHE
+ENV GOMODCACHE=${GOMODCACHE:-/go/pkg/mod}
+
 #Build deps
 RUN apk --no-cache add \
     build-base \
@@ -23,10 +29,17 @@ WORKDIR ${GOPATH}/src/code.gitea.io/gitea
 
 # Checkout version if set
 RUN if [ -n "${GITEA_VERSION}" ]; then git checkout "${GITEA_VERSION}"; fi \
- && make clean-all build
+ && make clean-all
+
+RUN --mount=type=cache,target=/root/.npm \
+  --mount=type=cache,target=/go/pkg/mod/ \
+  --mount=type=cache,target="/root/.cache/go-build" \
+  make build
 
 # Begin env-to-ini build
-RUN go build contrib/environment-to-ini/environment-to-ini.go
+RUN --mount=type=cache,target=/go/pkg/mod/ \
+  --mount=type=cache,target="/root/.cache/go-build" \
+  go build contrib/environment-to-ini/environment-to-ini.go
 
 # Copy local files
 COPY docker/rootless /tmp/local