Dockerfile

FROM golang:1.12.5-alpine3.9 as builder
RUN apk --no-cache add tzdata
COPY . /src
RUN go build -o /bin/timenow /src/timenow.go


FROM scratch
COPY --from=builder /bin/timenow /bin/timenow
# without these, TZ env is useless
COPY --from=builder /usr/share/zoneinfo /usr/share/zoneinfo
# https://golang.org/src/time/zoneinfo_unix.go
# COPY --from=builder /usr/share/lib/zoneinfo /usr/share/lib/zoneinfo
# COPY --from=builder /usr/lib/locale/TZ /usr/lib/locale/TZ

go.mod

module github.com/choonkeat/timenow

go 1.12

Makefile

run:
	docker build . -t timenow
	docker run --rm -it -e TZ=$(TZ) timenow /bin/timenow

timenow.go

package main

import (
	"log"
	"os"
	"time"
)

func main() {
	log.Println(os.Getenv("TZ"))
	log.Println(time.Now().Format(time.RFC3339))
}