Docker

Go - Docker

Folder structure

└── 📁Docker
    └── .env
    └── .gitignore
    └── Dockerfile
    └── go.mod
    └── go.sum
    └── main_test.go
    └── main.go
    └── Readme.md

Instructions

• step-1 clone the repo using the following command
  • git clone https://github.com/deepakgudla/Go-Hub.git
• step-2 change directory to Docker folder using the following command
  • cd Docker
• step-3Install the dependencies using the following command
  • go mod tidy
• step-4 Build the docker image using the following command
  • docker build -t deepakgudla/go-basic-server:v1 .
• step-5 Run the docker image using the following command
  • docker run -p 1357:1357 deepakgudla/go-basic-server:v1
  • docker run --env-file .env -p 1357:1357 deepakgudla/go-basic-server:v1
• step-6 To publish the image into Docker hub, please login using docker login
• step-7 Push the image into Docker Hub using the following command
  • docker push deepakgudla/go-basic-server:v1

Working of Application

• If you want to test this application directly, pull the image using the following command

  • docker pull deepakgudla/go-basic-server
  • open `http://localhost:1357' on your browser
  • You will be able to see Jai Mahishmathi ✊

• NOTE:

  • If you want to push the Docker image into your own Docker repository, login with your own docker credentials and replace deepakgudla with your docker username..

The Go web server

• main.go

  • This is a simple web server that listens on a port and responds with a text upon accessing the URL

• main_test.go

  • simple unit test to make sure that the web server is working fine

Dockerfile

• What is a Dockerfile ?
  • A Dockerfile defines how to build and run a lightweight, production ready container

Dockerfile explanation

• FROM golang:1.23.1 AS builder
  • FROM - it is a keyword
  • Uses the official Go (Golang) image version 1.23.1, which includes everything needed to compile Go code
  • AS builder - gives this stage a name builder
• WORKDIR /app
  • Sets the working directory inside the container to /app
  • All the commands after this will run inside the /app
• COPY go.mod ./
  • Copies the Go module files into the container.
• COPY go.sum ./
  • This file describes the app dependencies
• RUN go mod download
  • Downloads the dependencies described in the go.mod and go.sum files.
• COPY . ./
  • Copies the entire project (all source code) into the container’s /app directory.
• RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o main
  • Compiles the Go app into a binary named main
  • CGO_ENABLED=0 - disables C bindings for a fully static binary
  • GOOS=linux - Go OS, targets linux system
  • GOARCH - Go Architecture, targets 64 bit architecture
• FROM alpine:latest
  • Starts a second, clean image using Alpine Linux which is lightweight (has less features compared to ubuntu, efficient for single web server)
• Metadata
  • LABEL maintainer="deepakgudla"
  • LABEL org.opencontainers.image.source="https://github.com/deepakgudla/Go-Hub"
  • LABEL org.opencontainers.image.description="Basic Go server running on port 1357"
  • LABEL org.opencontainers.image.licenses="MIT"
  • These labels are metadata for the Docker image. The metadata can be found in Docker Hub or container registries
• RUN apk --no-cache add ca-certificates
  • Installs root SSL certificates needed for HTTPS connections.
• WORKDIR /root/
  • Sets the working directory to /root/ inside the container
• COPY --from=builder /app/main .
  • Copies the compiled main binary from the builder stage into the current stage
• EXPOSE 1357
  • The docker image is set to run on port 1357
  • It just exposes the port but does not actually publishes the port
• CMD ["./main"]
  • This is the command that tells Docker to run the main binary when the container starts
  • This launches the Go web server

Layers in the Docker image

• What is a Docker layer ?

  • Each step in a Dockerfile is considered as a layer.
  • Each layer is built on top of previous one
  • When the Dockerfile gets updated, Docker only rebuilds the layers that has been modified and the ones after it

• Layers in the current Dockerfile