Update golang version (#20)

Dockerfile

@@ -1,5 +1,5 @@
 # Dockerfile
-FROM golang:1.19 as base
+FROM golang:1.21.2 as base
 
 RUN adduser \
   --disabled-password \
@@ -10,19 +10,22 @@ RUN adduser \
   --uid 65532 \
   script
 
+USER script
 
-WORKDIR $GOPATH/src/app/
+WORKDIR /app/
 
 COPY . .
 
 RUN go mod download
 RUN go mod verify
 
-RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o /exporter .
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 GOCACHE=/tmp/go-cache go build -buildvcs=false -o ./exporter .
 
 FROM scratch
 
 COPY --from=base /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
-COPY --from=base /exporter .
+COPY --from=base /app/exporter .
 
-CMD ["./exporter"]
+# Since we're using scratch, there's no shell or user management. So, the process will run as the root user.
+# However, since scratch doesn't contain any OS files, there's minimal risk.
+CMD ["/exporter"]

go.mod

@@ -1,5 +1,5 @@
 module cbi-oi-kubecost-exporter
 
-go 1.19
+go 1.21.2
 
 require github.com/caarlos0/env/v7 v7.1.0