Docker Build Golang App in Stages for Production

In this post we are going to dockerize our go app it is very simple api server which is running on port 9900 this is very basic backend example which

package main

import (
	"fmt"
	"net/http"
)

func main() {
	// Define a handler function for the root endpoint ("/")
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, "Hello, World!")
	})

	// Start the server on port 8080
	fmt.Println("Server listening on :9900")
	http.ListenAndServe(":9900", nil)
}

Now create a Dockerfile in same directory and add the below content in that we will build the docker image in stages.
In first stage we will compile our code and create a executable build file and in second stage we will run our executable go binary in alpine container, we will use alpine container to make our image smaller

Dockerfile will look like below one

FROM golang:1.21.0-alpine3.17 as builder
WORKDIR /src
COPY src .
RUN go mod tidy
RUN go build -o myapp .

FROM alpine:latest 
WORKDIR /app
COPY --from=builder /src/myapp /app/myapp
RUN apk update
RUN apk add --no-cache libc6-compat 
ENTRYPOINT [ "./myapp" ]
EXPOSE 9900/tcp

Now build image by using the below command

docker  build  -t my-example-app  .

and to run it use below command

 docker run -p 9900:9900 my-example-app

If you are facing permission issue use sudo before the command
that’s it for this post