feat: add caching to dockerfile; remove no longer required nsswitch.c…

…onf overrides

Signed-off-by: Liam Stanley <[email protected]>

Dockerfile

@@ -1,22 +1,29 @@
+# syntax = docker/dockerfile:1.4
+
 # build image
 FROM golang:alpine as build
 WORKDIR /build
+
 RUN apk add --no-cache make
 COPY go.sum go.mod Makefile /build/
-RUN make go-fetch
+RUN \
+	--mount=type=cache,target=/root/.cache \
+	--mount=type=cache,target=/go \
+	make go-fetch
+
 COPY . /build/
-RUN make
+RUN \
+	--mount=type=cache,target=/root/.cache \
+	--mount=type=cache,target=/go \
+	make
 
 # runtime image
 FROM alpine:3.18
 RUN apk add --no-cache ca-certificates
-# set up nsswitch.conf for Go's "netgo" implementation
-# - https://github.com/docker-library/golang/blob/1eb096131592bcbc90aa3b97471811c798a93573/1.14/alpine3.12/Dockerfile#L9
-RUN if [ ! -e /etc/nsswitch.conf ];then echo 'hosts: files dns' > /etc/nsswitch.conf;fi
 COPY --from=build /build/vault-unseal /usr/local/bin/vault-unseal
 
 # runtime params
 WORKDIR /
 ENV PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 ENV LOG_JSON=true
-CMD ["vault-unseal"]
+CMD ["/usr/local/bin/vault-unseal"]