Building Containerized Microservices in Golang Chapter 3 – Docker

I’m going to create two types of docker files. One for the local testing, and one for the production. Before creating the docker file, I want to create the docker ignore file because geometry and static folders are not used.

#.dockerignore

geometry/
static/
*.exe

Create dockerfile

FROM golang:latest

WORKDIR /app
COPY go.mod go.sum ./

RUN go mod download
COPY . .
RUN go build -o main .

EXPOSE 80
ENTRYPOINT [ "./main" ]

build and run

docker build -t go-app:latest .
docker run -d -p 80:80 --name web go-app:latest

The problem of this image has 974MB which is way too big for a simple application. I will use multi stage builds.

FROM golang:latest as builder

WORKDIR /app
COPY go.mod go.sum ./

RUN go mod download
COPY . .
RUN go build -o main .
# EXPOSE 80
# ENTRYPOINT [ "./main" ]

# Second stage
FROM gcr.io/distroless/base-debian11
COPY --from=builder /app/main .
EXPOSE 80
CMD ["/main"]

Much better! 👏

Docker-compose file

// docker-compose.yml
version: "3.9"
services:
  web:
    # build from here
    build:
      # the location where your dockerfile is existing
      context: .
      dockerfile: Dockerfile
    #name of image
    image: go-app-ms:latest
    ports:
      - "80:80"
    # always restart 
    restart: always
    networks:
      - web

networks:
  web:

docker-compose build
docker-compose up -d