100DaysOfCode — Day 06

This is a simple tutorial demonstrates creating Golang Docker image.

Prerequisites:

• Day 5 tutorial

Go App

Create a simple Go program hello-http.go:

package main

import (
    "fmt"
    "log"
    "net/http"
)

func hello(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "hello world\n")
}

func main() {
    http.HandleFunc("/", hello)
    log.Println("Starting server on 0.0.0.0:8080")
    http.ListenAndServe(":8080", nil)
}

Docker file

In the same directory, create Docker manifest file (Dockerfile):

# initializes a new build stage and sets the base image
FROM golang:1.15.1-alpine

# copy hello-http.go and add it to the filesystem of the image
ADD hello-http.go .

# compile the program
RUN go build hello-http.go

# provide the default command for the container
CMD ["/go/hello-http"]

docker build

Build an image from your Dockerfile

$ docker build . -t hello:v1.0.0

• -t Name and tag the image in the 'name:tag' format

List docker images:

$ docker images

REPOSITORY                         TAG       IMAGE ID       CREATED          SIZE
hello                              v1.0.0    47f0babcdfe2   44 minutes ago   306MB

run the command:

$ docker run -dit --rm -p 8080:8080 --name hello hello:v1.0.0

• docker run Run a command in a new container
• -d Run container in background and print container ID
• -i interactive
• -t Allocate a pseudo-TTY
• --rm Automatically remove the container when it exits
• -p 8080:8080 Publish a container's port(s) to the host
• hello:v1.0.0 Docker image to run
• --name hello Assign a name to the container

Test your container

$ docker ps

• docker ps List containers

You see a list like this shows a container running hello image.

CONTAINER ID   IMAGE          COMMAND            CREATED          STATUS          PORTS                    NAMES
7c3c8774134d   hello:v1.0.0   "/go/hello-http"   54 minutes ago   Up 54 minutes   0.0.0.0:8080->8080/tcp   hello

Now open your browser and go to http://localhost:8080/:

End the container

Now run the following command to end the container:

$ docker stop hello

Now list the containers

$ docker ps

CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

Note that docker container has stopped and automatically removed:

$ docker ps -a

You will see this:

CONTAINER ID   IMAGE                    COMMAND                  CREATED          STATUS                     PORTS     NAMES

End of day 6 of 100DaysOfCode.