Multistage Go Application

We will use multistage docker builds from a alpine image as our build image to get the dependencies, build the go binary and use our scratch image to place the built binary onto our target image to have small docker images.

Go Application

We will use a library that generates random data from go-randomdata in our application, app.go:

package main

import (
    "fmt"
    "github.com/Pallinder/go-randomdata"
)

func main() {
    profile := randomdata.GenerateProfile(randomdata.Male | randomdata.Female | randomdata.RandomGender)
    fmt.Printf("The new profile's username is: %s and password (md5): %s\n", profile.Login.Username, profile.Login.Md5)
}

Dockerize the Application

Our multi-stage Dockerfile:

FROM golang:1.11.1 as builder
RUN mkdir -p /go/src/github.com/ruanbekker
WORKDIR /go/src/github.com/ruanbekker
RUN useradd -u 10001 app
COPY . .
RUN go get
RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o main .

FROM scratch
COPY --from=builder /go/src/github.com/ruanbekker/main /main
COPY --from=builder /etc/passwd /etc/passwd
USER app
CMD ["/main"]

Build the image:

docker build -t myapp:v2 .

Run a container:

docker run -it myapp:v2

# output
The new profile's username is: Kingcat and password (md5): 11a8c854fa051287aedc0bb3466e3d44