Build and deploy a Golang application to Docker Hub
In this article, you will learn a very basic example of how to build, test and deploy a Golang application into the Docker Hub. To do so we will use the Github Actions.
The Github repository
I assume that you created the Github repository, added a README, etc.. For this post, I will call the application awesomeapp.
The Golang application
Let’s create a very basic Web application with Golang that will sum two integers and display the result into the browser.
package main
import (
"fmt"
"log"
"net/http"
)
func handler(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, sum(1,2))
}
func sum(a, b int) int {
return a + b
}
func main() {
http.HandleFunc("/", handler)
log.Fatal(http.ListenAndServe(":8000", nil))
}
This very simple application will basically print Hello World on a Web page.
Do not forget the tests
Let’s write some basic tests for the sum() function.
package main
import (
"testing"
)
func TestSum(t *testing.T) {
if sum(1,1) != 2 {
t.Fatalf(`should be 3 but got %d`, sum(1,1))
}
}
The Dockerfile
At the root of the project, we also need to add a Dockerfile:
FROM golang:latest as builder
WORKDIR /go/src/awesomeapp
ADD . /go/src/awesomeapp
RUN go get -d -v ./...
RUN go build -o /go/bin/awesomeapp
FROM gcr.io/distroless/base-debian10
COPY --from=builder /go/bin/awesomeapp /
CMD [ "/awesomeapp" ]
Deploy it !
name: Deploy to Docker registry
on:
push:
jobs:
push_to_registry:
name: Push Docker image to Docker Hub
runs-on: ubuntu-latest
steps:
- name: Check out the repo
uses: actions/checkout@v2
- name: Log in to Docker Hub
uses: docker/login-action@v1
with:
username: ${{ secrets.DOCKER_USERNAME }}
password: ${{ secrets.DOCKER_PASSWORD }}
- name: Extract metadata (tags, labels) for Docker
id: meta
uses: docker/metadata-action@v3
with:
images: username/awesomeapp
- name: Build and push Docker image
uses: docker/build-push-action@v3
with:
context: .
push: true
tags: ${{ steps.meta.outputs.tags }}
labels: ${{ steps.meta.outputs.labels }}